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Sample records for behavior surfactant retention

  1. Phase Behavior of Laundry Surfactants in Polar Solvents

    NARCIS (Netherlands)

    Stuart, Marc C.A.; Pas, John C. van de; Engberts, Jan B.F.N.

    2006-01-01

    Laundry surfactants are usually mixtures of ionic and nonionic detergents that exhibit a complex phase behavior. Here the ternary phase behavior of an isotropic and a liquid crystalline (LC) surfactant mixture has been examined in water/solvent systems. The size of the LC area in the ternary phase

  2. Complex phase behavior in solvent-free nonionic surfactants

    DEFF Research Database (Denmark)

    Hillmyer, M.A.; Bates, F.S.; Almdal, K.

    1996-01-01

    Unsolvated block copolymers and surfactant solutions are ''soft materials'' that share a common set of ordered microstructures, A set of polyethyleneoxide-polyethylethylene (PEG-PEE) block copolymers that are chemically similar to the well-known alkane-oxyethylene (C(n)EO(m)) nonionic surfactants...... was synthesized here. The general phase behavior in these materials resembles that of both higher molecular weight block copolymers and lower molecular weight nonionic surfactant solutions. Two of the block copolymers exhibited thermally induced order-order transitions and were studied in detail by small...

  3. Reducing plant uptake of PAHs by cationic surfactant-enhanced soil retention

    Energy Technology Data Exchange (ETDEWEB)

    Lu Li, E-mail: ll19840106@zju.edu.c [Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310028 (China); Zhu Lizhong, E-mail: zlz@zju.edu.c [Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310028 (China); Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, Zhejiang University, Hangzhou, Zhejiang 310029 (China)

    2009-06-15

    Reducing the transfer of contaminants from soils to plants is a promising approach to produce safe agricultural products grown on contaminated soils. In this study, 0-400 mg/kg cetyltrimethylammonium bromide (CTMAB) and dodecylpyridinium bromide (DDPB) were separately utilized to enhance the sorption of PAHs onto soils, thereby reducing the transfer of PAHs from soil to soil solution and subsequently to plants. Concentrations of phenanthrene and pyrene in vegetables grown in contaminated soils treated with the cationic surfactants were lower than those grown in the surfactant-free control. The maximum reductions of phenanthrene and pyrene were 66% and 51% for chrysanthemum (Chrysanthemum coronarium L.), 62% and 71% for cabbage (Brassica campestris L.), and 34% and 53% for lettuce (Lactuca sativa L.), respectively. Considering the impacts of cationic surfactants on plant growth and soil microbial activity, CTMAB was more appropriate to employ, and the most effective dose was 100-200 mg/kg. - Cationic surfactants could enhance the retention of PAHs in soil, and reduce PAH transfer to and accumulation in vegetables.

  4. Controlling block copolymer phase behavior using ionic surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Ray, D.; Aswal, V. K. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India E-mail: debes.phys@gmail.com (India)

    2016-05-23

    The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO{sub 26}PO{sub 39}EO{sub 26})] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle–surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

  5. Computer simulation-molecular-thermodynamic framework to predict the micellization behavior of mixtures of surfactants: application to binary surfactant mixtures.

    Science.gov (United States)

    Iyer, Jaisree; Mendenhall, Jonathan D; Blankschtein, Daniel

    2013-05-30

    We present a computer simulation-molecular-thermodynamic (CSMT) framework to model the micellization behavior of mixtures of surfactants in which hydration information from all-atomistic simulations of surfactant mixed micelles and monomers in aqueous solution is incorporated into a well-established molecular-thermodynamic framework for mixed surfactant micellization. In addition, we address the challenges associated with the practical implementation of the CSMT framework by formulating a simpler mixture CSMT model based on a composition-weighted average approach involving single-component micelle simulations of the mixture constituents. We show that the simpler mixture CSMT model works well for all of the binary surfactant mixtures considered, except for those containing alkyl ethoxylate surfactants, and rationalize this finding molecularly. The mixture CSMT model is then utilized to predict mixture CMCs, and we find that the predicted CMCs compare very well with the experimental CMCs for various binary mixtures of linear surfactants. This paper lays the foundation for the mixture CSMT framework, which can be used to predict the micellization properties of mixtures of surfactants that possess a complex chemical architecture, and are therefore not amenable to traditional molecular-thermodynamic modeling.

  6. The effect of pressure on the phase behavior of surfactant systems: An experimental study

    DEFF Research Database (Denmark)

    Sandersen, Sara Bülow; Stenby, Erling Halfdan; von Solms, Nicolas

    2012-01-01

    Enhanced oil recovery is employed in many mature oil reservoirs to maintain or increase the reservoir recovery factor. In this context, surfactant flooding has recently gained interest again. Surfactant flooding is the injection of surfactants (and co-surfactants) into the reservoir, in order...... is influenced to an even greater extent. It was concluded that at certain compositions of the surfactant system (near to the phase boundary found at atmospheric pressure) the increase in pressure changed the phase behavior (for example causing the system to move from two phases to three or vice versa...

  7. Thickness-Dependent Surfactant Behavior in Trilayer Polymer Films

    Science.gov (United States)

    Sun, Yan; Shull, Kenneth; Wang, Jin

    2010-03-01

    The ability for thin liquid films to wet and remain thermodynamically stable on top of one another is a fundamental challenge in developing high quality paints, coatings, adhesives, and other industrial products. Since intermolecular interactions and interfacial energies dominate in the film thickness regime from tens to hundreds of nanometers, it is desirable to tune these long-range and short-range forces in a simple, controllable manner. Starting from an unstable model homopolymer bilayer (poly(styrene)/poly(4-vinylpyridine)), we demonstrate that sandwiching an additional homopolymer layer (poly(4-bromostyrene)) between the two layers can provide needed surfactancy. As the thickness of this center layer is increased, the full trilayer transitions from unstable (thin) to stable (moderate) to unstable (thick). We experimentally show using x-ray standing waves generated via total external reflection (TER-XSW), atomic force microscopy (AFM), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) that this behavior can be directly attributed to the autophobic dewetting phenomenon, in which the surfactant layer is thin enough to remain stable but thick enough to shield the neighboring layers, highlighting a general approach to stabilizing multilayer systems.

  8. New theoretical framework for designing nonionic surfactant mixtures that exhibit a desired adsorption kinetics behavior.

    Science.gov (United States)

    Moorkanikkara, Srinivas Nageswaran; Blankschtein, Daniel

    2010-12-21

    How does one design a surfactant mixture using a set of available surfactants such that it exhibits a desired adsorption kinetics behavior? The traditional approach used to address this design problem involves conducting trial-and-error experiments with specific surfactant mixtures. This approach is typically time-consuming and resource-intensive and becomes increasingly challenging when the number of surfactants that can be mixed increases. In this article, we propose a new theoretical framework to identify a surfactant mixture that most closely meets a desired adsorption kinetics behavior. Specifically, the new theoretical framework involves (a) formulating the surfactant mixture design problem as an optimization problem using an adsorption kinetics model and (b) solving the optimization problem using a commercial optimization package. The proposed framework aims to identify the surfactant mixture that most closely satisfies the desired adsorption kinetics behavior subject to the predictive capabilities of the chosen adsorption kinetics model. Experiments can then be conducted at the identified surfactant mixture condition to validate the predictions. We demonstrate the reliability and effectiveness of the proposed theoretical framework through a realistic case study by identifying a nonionic surfactant mixture consisting of up to four alkyl poly(ethylene oxide) surfactants (C(10)E(4), C(12)E(5), C(12)E(6), and C(10)E(8)) such that it most closely exhibits a desired dynamic surface tension (DST) profile. Specifically, we use the Mulqueen-Stebe-Blankschtein (MSB) adsorption kinetics model (Mulqueen, M.; Stebe, K. J.; Blankschtein, D. Langmuir 2001, 17, 5196-5207) to formulate the optimization problem as well as the SNOPT commercial optimization solver to identify a surfactant mixture consisting of these four surfactants that most closely exhibits the desired DST profile. Finally, we compare the experimental DST profile measured at the surfactant mixture condition

  9. Transport and retention of surfactant- and polymer-stabilized engineered silver nanoparticles in silicate-dominated aquifer material

    Science.gov (United States)

    Packed column experiments were conducted to investigate the transport and blocking behavior of surfactant- and polymer-stabilized engineered silver nanoparticles (Ag-ENPs) in saturated natural aquifer material with varying silt and clay content, background solution chemistry, and flow velocity. Brea...

  10. Screening of mixed surfactant systems: Phase behavior studies and CT imaging of surfactant-enhanced oil recovery experiments

    Energy Technology Data Exchange (ETDEWEB)

    Llave, F.M.; Gall, B.L.; Lorenz, P.B.; Cook, I.M.; Scott, L.J.

    1993-11-01

    A systematic chemical screening study was conducted on selected anionic-nonionic and nonionic-nonionic systems. The objective of the study was to evaluate and determine combinations of these surfactants that would exhibit favorable phase behavior and solubilization capacity. The effects of different parameters including (a) salinity, (b) temperature, (c) alkane carbon number, (c) hydrophilic/lipophilic balance (HLB) of nonionic component, and (d) type of surfactant on the behavior of the overall chemical system were evaluated. The current work was conducted using a series of ethoxylated nonionic surfactants in combinations of several anionic systems with various hydrocarbons. Efforts to correlate the behavior of these mixed systems led to the development of several models for the chemical systems tested. The models were used to compare the different systems and provided some guidelines for formulating them to account for variations in salinity, oil hydrocarbon number, and temperature. The models were also evaluated to determine conformance with the results from experimental measurements. The models provided good agreement with experimental results. X-ray computed tomography (CT) was used to study fluid distributions during chemical enhanced oil recovery experiments. CT-monitored corefloods were conducted to examine the effect of changing surfactant slug size injection on oil bank formation and propagation. Reducing surfactant slug size resulted in lower total oil production. Oil recovery results, however, did not correlate with slug size for the low-concentration, alkaline, mixed surfactant system used in these tests. The CT measurements showed that polymer mobility control and core features also affected the overall oil recovery results.

  11. The Relevance of Retention Behavior in the Development of Accession Strategy

    National Research Council Canada - National Science Library

    Gonzales, Jose

    2002-01-01

    .... The findings reveal that each accession source has unique accession to retention ratios. A comparison of the retention ratios to accession trends reveals that retention rates can be improved through an understanding of retention behavior...

  12. The effect of surfactants on the dissolution behavior of amorphous formulations

    DEFF Research Database (Denmark)

    Mah, Pei T; Peltonen, Leena; Novakovic, Dunja

    2016-01-01

    The optimal design of oral amorphous formulations benefits from the use of excipients to maintain drug supersaturation and thus ensures adequate absorption during intestinal transit. The use of surfactants for the maintenance of supersaturation in amorphous formulations has not been investigated...... in detail. The main aim of this study was to investigate the effect of surfactant on the dissolution behavior of neat amorphous drug and binary polymer based solid dispersion. Indomethacin was used as the model drug and the surfactants studied were polysorbate 80 and poloxamer 407. The presence...... of surfactants (alone or in combination with polymers) in the buffer was detrimental to the dissolution of neat amorphous indomethacin, suggesting that the surfactants promoted the crystallization of neat amorphous indomethacin. In contrast, the presence of surfactants (0.01% w/v) in the buffer resulted...

  13. Demonstrating the Effect of Surfactant on Water Retention of Waxy Leaf Surfaces

    Science.gov (United States)

    Chiu, Yu-Chun; Jenks, Matthew A.; Richards-Babb, Michelle; Ratclif, Betsy B.; Juvik, John A.; Ku, Kang-Mo

    2017-01-01

    We report here the development of an inexpensive and engaging laboratory-based activity that can help students learn about the scientific method and the role of plant epicuticular waxes and surfactant function on waxy plant leaves as real life example in the agricultural industry. Three each of nontreated collard leaves ("Brassica…

  14. Surfactants in aquatic and terrestrial environment: occurrence, behavior, and treatment processes.

    Science.gov (United States)

    Jardak, K; Drogui, P; Daghrir, R

    2016-02-01

    Surfactants belong to a group of chemicals that are well known for their cleaning properties. Their excessive use as ingredients in care products (e.g., shampoos, body wash) and in household cleaning products (e.g., dishwashing detergents, laundry detergents, hard-surface cleaners) has led to the discharge of highly contaminated wastewaters in aquatic and terrestrial environment. Once reached in the different environmental compartments (rivers, lakes, soils, and sediments), surfactants can undergo aerobic or anaerobic degradation. The most studied surfactants so far are linear alkylbenzene sulfonate (LAS), quaternary ammonium compounds (QACs), alkylphenol ethoxylate (APEOs), and alcohol ethoxylate (AEOs). Concentrations of surfactants in wastewaters can range between few micrograms to hundreds of milligrams in some cases, while it reaches several grams in sludge used for soil amendments in agricultural areas. Above the legislation standards, surfactants can be toxic to aquatic and terrestrial organisms which make treatment processes necessary before their discharge into the environment. Given this fact, biological and chemical processes should be considered for better surfactants removal. In this review, we investigate several issues with regard to: (1) the toxicity of surfactants in the environment, (2) their behavior in different ecological systems, (3) and the different treatment processes used in wastewater treatment plants in order to reduce the effects of surfactants on living organisms.

  15. Shedding light on the different behavior of ionic and nonionic surfactants in emulsion polymerization: from atomistic simulations to experimental observations.

    Science.gov (United States)

    Magi Meconi, Giulia; Ballard, Nicholas; Asua, José M; Zangi, Ronen

    2017-12-06

    Although surfactants are known to play a vital role in polymerization reactions carried out in dispersed media, many aspects of their use are poorly understood, perhaps none more so than the vastly different action of ionic and nonionic surfactants in emulsion polymerization. In this work, we combine experimental measurements of emulsion polymerization of styrene with atomistic molecular dynamics simulations to better understand the behavior of surfactants at monomer/polymer-water interfaces. In a batch emulsion polymerization of styrene, the nonionic surfactant Disponil AFX 1080 leads to two nucleation periods, in contrast to the behavior observed for the ionic surfactant SDS. This can be explained by the absorption of the nonionic surfactant into the organic phase at the early stages of the polymerization reaction which is then released as the reaction progresses. Indeed, we find that the partition coefficient of the surfactant between the organic phase and water increases with the amount of monomer in the former, and preferential partitioning is detected to organic phases containing at least 55% styrene. Results from molecular dynamics simulations confirm that spontaneous dissolution of the non-ionic surfactant into a styrene-rich organic phase occurs above a critical concentration of the surfactant adsorbed at the interface. Above this critical concentration, a linear correlation between the amount of surfactant adsorbed at the interface and that absorbed inside the organic phase is observed. To facilitate this absorption into a completely hydrophobic medium, water molecules accompany the intruding surfactants. Similar simulations but with the ionic surfactant instead did not result in any absorption of the surfactant into a neat styrene phase, likely because of its strongly hydrophilic head group. The unusual partitioning behavior of nonionic surfactants explains a number of observable features of emulsion polymerization reactions which use nonionic

  16. 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.

  17. Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants

    Science.gov (United States)

    Bouchal, Roza; Hamel, Abdellah; Hesemann, Peter; In, Martin; Prelot, Bénédicte; Zajac, Jerzy

    2016-01-01

    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. PMID:26861309

  18. The effect of surfactants on the electropolishing behavior of copper in orthophosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Taha, A.A., E-mail: asia_taha@yahoo.com; Ahmed, A.M.; Rahman, H.H. Abdel; Abouzeid, F.M.

    2013-07-15

    The electropolishing behavior of copper was studied in orthophosphoric acid with Triton X-100, sodium dodecyl sulphate and cetyl pyridinium chloride as additives for improving the finish obtained on copper surface. This was investigated by measuring and comparing anode potential-limiting current relationships in solutions of gradually increasing concentration of surfactants. The addition of surfactants to the electropolishing solution results in a lower limiting current. This confirms the mass transport of dissolved species from the anode surface to the bulk of solution as the rate-determining step in the presence of three surfactants in all concentrations investigated. Scanning electron microscope (SEM), atomic force microscope (AFM) and measured brightness values were used to investigate the copper surface after electropolishing and the results were compared to polishing done in absence of surfactants. According to SEM images and brightness values, addition of Triton X-100 was effective to enhance levelling and brightening more than sodium dodecyl sulphate and cetyl pyridinium chloride. AFM analysis showed that the roughness values (R{sub a}) for an electropolished copper surface, in presence of surfactants, is significantly lower than in absence of surfactants. Different reaction conditions and the physical properties of solutions are studied to obtain dimensionless correlation among all these parameters.

  19. The relationship between managerial leadership behaviors and staff nurse retention.

    Science.gov (United States)

    Kleinman, Carol

    2004-01-01

    The purposes of this study were to describe perceptions of managerial leadership behaviors associated with staff nurse turnover and to compare nurse manager leadership behaviors as perceived by managers and their staff nurses. Effective leadership styles among nurse managers have been associated with staff nurse job satisfaction and retention. Although both transformational and transactional leadership styles have been described as effective, it is unclear which nurse manager leadership behaviors contribute most to staff nurse retention. This descriptive, correlational study was conducted at a 465-bed community hospital in the northeastern United States. All staff nurses and nurse managers employed in both ambulatory and acute care nursing units were invited to participate in the study. The study sample comprised 79 staff nurses and 10 nurse managers, who completed demographic forms and the 45-item Multifactor Leadership Questionnaire, which measures 12 dimensions of leadership style. Data were collected from July through September 2003. Active management by exception as perceived by staff nurses was the only managerial leadership style associated with staff nurse turnover (r = .26, p = .03). Compared with the perceptions among their staff nurses, nurse managers consistently perceived that they demonstrated a higher mean frequency of transformational leadership behaviors. The transactional leadership style of active management by exception not only appeared to be a deterrent to staff nurse retention but also reflected leadership perceptions among staff nurses who work evening and night shifts. This study also provides further evidence regarding a trend in which nurse managers and staff nurses do not concur on the frequency of transformational leadership behaviors but do demonstrate agreement on the frequency of transactional leadership behaviors.

  20. 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.

  1. [Impacts of pH and surfactants on adsorption behaviors of norfloxacin on marine sediments].

    Science.gov (United States)

    Pang, Hui-Ling; Yang, Gui-Peng; Gao, Xian-Chi; Cao, Xiao-Yan

    2012-01-01

    The adsorption behaviors of norfloxacin (NOR) on marine sediments at different pH values and in the presence of four different surfactants were systematically investigated by a batch equilibrium method. The results indicated that Freundlich adsorption isotherms fitted the adsorption behavior of NOR on marine sediments very well at different pH values. The Freundlich constant K(F) and the equilibrium adsorption amount of NOR reduced with the increase of pH values, and the minimum appeared at pH 8.10. The results suggested that cation exchange was the main adsorption mechanism of NOR at pH 6.01, while Van der Waals' force, hydrophobic effects, electrostatic force were the major adsorption mechanism of NOR on marine sediments at pH 8.10. The adsorption process fitted well with pseudo-second-order kinetic equations with the addition of surfactants. Our study also indicated that the addition of surfactants had the significant influence on the saturated adsorption amount of adsorption of NOR. The equilibrium adsorption amount (Q(e)) of NOR exhibited the following sequence: Q(e) (Tween80) < Q(e) (Tween20)

  2. [Systematic evaluation of retention behavior of carbohydrates in hydrophilic interaction liquid chromatography].

    Science.gov (United States)

    Fu, Qing; Wang, Jun; Liang, Tu; Xu, Xiaoyong; Jin, Yu

    2013-11-01

    A systematic evaluation of retention behavior of carbohydrates in hydrophilic interaction liquid chromatography (HILIC) was performed. The influences of mobile phase, stationary phase and buffer salt on the retention of carbohydrates were investigated. According to the results, the retention time of carbohydrates decreased as the proportion of acetonitrile in mobile phase decreased. Increased time of carbohydrates was observed as the concentration of buffer salt in mobile phase increased. The retention behavior of carbohydrates was also affected by organic solvent and HILIC stationary phase. Furthermore, an appropriate retention equation was used in HILIC mode. The retention equation lnk = a + blnC(B) + cC(B) could quantitatively describe the retention factors of carbohydrates of plant origin with good accuracy: the relative error of the predicted time to actual time was less than 0.3%. The evaluation results could provide guidance for carbohydrates to optimize the experimental conditions in HILIC method development especially for carbohydrate separation

  3. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    P. Somasundaran

    2004-11-20

    The aim of the project is to develop a knowledge base to help the design of enhanced processes for mobilizing and extracting untrapped oil. We emphasize evaluation of novel surfactant mixtures and obtaining optimum combinations of the surfactants for efficient chemical flooding EOR processes. In this regard, an understanding of the aggregate shape, size and structure is crucial since these properties govern the crude oil removal efficiency. During the three-year period, the adsorption and aggregation behavior of sugar-based surfactants and their mixtures with other types of surfactants have been studied. Sugar-based surfactants are made from renewable resources, nontoxic and biodegradable. They are miscible with water and oil. These environmentally benign surfactants feature high surface activity, good salinity, calcium and temperature tolerance, and unique adsorption behavior. They possess the characteristics required for oil flooding surfactants and have the potential for replacing currently used surfactants in oil recovery. A novel analytical ultracentrifugation technique has been successfully employed for the first time, to characterize the aggregate species present in mixed micellar solution due to its powerful ability to separate particles based on their size and shape and monitor them simultaneously. Analytical ultracentrifugation offers an unprecedented opportunity to obtain important information on mixed micelles, structure-performance relationship for different surfactant aggregates in solution and their role in interfacial processes. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. Four softwares: OptimaTM XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity

  4. Viscosity and sedimentation behaviors of the magnetorheological suspensions with oleic acid/dimer acid as surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jianjian; Yan, Hua; Hu, Zhide; Ding, Ding

    2016-11-01

    This work deals with the role of polar interactions on the viscosity and sedimentation behaviors of magnetorheological suspensions with micro-sized magnetic particles dispersed in oil carriers. The oleic acid and dimer acid were employed to make an adjustment of the hydrophobicity of iron particles, in the interest of performing a comparative evaluation of the contributions of the surface polarity. The viscosity tests show that the adsorbed surfactant layer may impose a hindrance to the movement of iron particles in the oil medium. The polar attractions between dimer acid covered particles gave rise to a considerable increase in viscosity, indicating flocculation structure developed in the suspensions. The observed plateau-like region in the vicinity of 0.1 s{sup −1} for MRF containing dimer acid is possibly due to the flocculation provoked by the carboxylic polar attraction, in which the structure is stable against fragmentation. Moreover, a quick recovery of the viscosity and a higher viscosity-temperature index also suggest the existence of particle-particle polar interaction in the suspensions containing dimer acid. The sedimentation measurements reveal that the steric repulsion of oleic acid plays a limited role in the stability of suspensions only if a large quantity of surfactant was used. The sedimentation results observed in the dimer acid covered particles confirm that loose and open flocculation was formed and enhanced sedimentation stability. - Highlights: • Surfactants were employed to make adjustments of the hydrophobicity of particles. • Polar attractions between particles increased the viscosity considerably. • Loose and open flocculation was formed in CI/DA suspension. • The steric repulsion of oleic acid played a limited role in the stability.

  5. Thermally cleavable surfactants

    Science.gov (United States)

    McElhanon, James R [Manteca, CA; Simmons, Blake A [San Francisco, CA; Zifer, Thomas [Manteca, CA; Jamison, Gregory M [Albuquerque, NM; Loy, Douglas A [Albuquerque, NM; Rahimian, Kamyar [Albuquerque, NM; Long, Timothy M [Urbana, IL; Wheeler, David R [Albuquerque, NM; Staiger, Chad L [Albuquerque, NM

    2006-04-04

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments and the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  6. Thermally cleavable surfactants

    Science.gov (United States)

    McElhanon, James R [Manteca, CA; Simmons, Blake A [San Francisco, CA; Zifer, Thomas [Manteca, CA; Jamison, Gregory M [Albuquerque, NM; Loy, Douglas A [Albuquerque, NM; Rahimian, Kamyar [Albuquerque, NM; Long, Timothy M [Urbana, IL; Wheeler, David R [Albuquerque, NM; Staiger, Chad L [Albuquerque, NM

    2009-11-24

    Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments or the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

  7. Mate retention behavior of men and women in heterosexual and homosexual relationships.

    Science.gov (United States)

    Vanderlaan, Doug P; Vasey, Paul L

    2008-08-01

    Comparing the behavior of heterosexual and homosexual persons can provide insight into the origins of heterosexual sex differences in psychology. Evidence indicates that, aside from sexual partner preference, the mating psychology of homosexual men is sex-typical whereas that of homosexual women tends to be more sex-atypical. The current study examined one aspect of mating psychology, mate retention behavior, and tested whether homosexual men and women were sex-typical or sex-atypical for those mate retention tactics where heterosexual men and women differed. Men and women in heterosexual and homosexual relationships were asked to provide information regarding their partners' mate retention behavior by using the Mate Retention Inventory Questionnaire. Heterosexual men and women differed significantly for six of the 19 mate retention tactics considered. With respect to the six mate retention tactics where heterosexual sex differences existed, homosexual men behaved in a sex-typical manner for five of the tactics, whereas homosexual women behaved in a sex-atypical manner for all six tactics. We discuss the significance of these findings for explaining the origins of the mate retention behavior of heterosexual men and women. In addition, we consider what the pattern of sex-typical and sex-atypical mating psychology among homosexual men and women, respectively, suggests in regard to sex differences in the development of mating psychology and the development of homosexual persons.

  8. Men's Benefit-Provisioning Mate Retention Behavior Mediates the Relationship Between Their Agreeableness and Their Oral Sex Behaviors.

    Science.gov (United States)

    Pham, Michael N; Shackelford, Todd K; Holden, Christopher J; Zeigler-Hill, Virgil; Sela, Yael; Jeffery, Austin John

    2015-08-01

    Men perform oral sex on their romantic partner as part of a broader benefit-provisioning mate retention strategy and men higher in Agreeableness are especially likely to provision their partner with benefits. The current research explored whether men's benefit-provisioning mate retention behavior mediated the relationship between their Agreeableness and their oral sex behaviors in their long-term romantic relationship. Men (n = 346) in a committed, sexual, heterosexual relationship completed the Mate Retention Inventory-a 104-item instrument that assesses the frequency with which they performed various mate retention behaviors during the past month, a 40-item personality inventory, and reported on a questionnaire their interest in and the time they spent performing oral sex on their romantic partner during their most recent sexual encounter with her. The results indicated that men higher in Agreeableness reported greater interest in and spent more time performing oral sex on their partner, and that their benefit-provisioning mate retention behaviors partially mediated these relationships. The current research is the first to investigate the relationship between personality dimensions and oral sex behaviors and adds to a growing body of research documenting that mate retention strategies influence sexual behavior.

  9. A Review on the Environmental Behavior of the Polyoxyethylene Type Nonionic Surfactants Adjuvants in Pesticides

    Directory of Open Access Journals (Sweden)

    KONG Xiang-ji

    2017-05-01

    Full Text Available Polyoxyethylene type nonionic surfactants such as alkylphenol ethoxylates(APEOs, alcohol ethoxylates(AEOs and alkylamine ethoxylates(ANEOs are typical pesticide adjuvants. Their unique environmental behavior characteristic is reflected in the parameters describing the fate e.g.distribution coefficient, adsorption to soil, degradation and effects of these substances. The major environmental problem related to these compounds is their part metabolites' relatively higher environmental risk. In views of their chemical structure, this paper outlined present knowledge on occurrence, fate and environment effect of the three adjuvants:AEOs, ANEOs and APEOs. The adsorption behaviour of ANEOs in contrast to AEOs was particularly variable and matrix dependent due to the ability of the compound to ionise at environmentally relevant pH. Probably because the compounds exceeded high soil adsorption and were easily degradable which were reflected in the low environmental concentrations generally found in monitoring studies.

  10. Retention behavior of resorcinarene-based cavitands on C8 and C18 stationary phases.

    Science.gov (United States)

    Bartó, Endre; Prauda, Ibolya; Kilár, Ferenc; Kiss, Ibolya; Felinger, Attila

    2015-09-01

    The understanding of the retention behavior of large molecules is an area of interest in liquid chromatography. Resorcinarene-based cavitands are cavity-shaped cyclic oligomers that can create host-guest interactions. We have investigated the chromatographic behavior of two types of cyclic tetramers as analytes in high-performance liquid chromatography. The experiments were performed at four different temperatures (15, 25, 35, 45°C) on two types of reversed stationary phases (C8 and C18 ) from two different manufacturers. We have found a huge difference between the retention of resorcinarenes and cavitands. In some cases, the retention factor of cavitands was even a hundred times larger than the retention factor of resorcinarenes. The retention of methylated derivates was two to four times larger compared to that of demethylated compounds on every column. The opposite retention behavior of the resorcinarenes and cavitands on the two types of stationary phases showed well the difference of the selectivity of the XTerra and BDS Hypersil columns. The retention mechanism was studied by the thermodynamic parameters calculated from the van't Hoff equation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Effect of ionic surfactants on the phase behavior and structure of sucrose ester/water/oil systems.

    Science.gov (United States)

    Rodríguez, Carlos; Acharya, Durga P; Hinata, Shigeki; Ishitobi, Masahiko; Kunieda, Hironobu

    2003-06-15

    The phase behavior and structure of sucrose ester/water/oil systems in the presence of long-chain cosurfactant (monolaurin) and small amounts of ionic surfactants was investigated by phase study and small angle X-ray scattering. In a water/sucrose ester/monolaurin/decane system at 27 degrees C, instead of a three-phase microemulsion, lamellar liquid crystals are formed in the dilute region. Unlike other systems in the presence of alcohol as cosurfactant, the HLB composition does not change with dilution, since monolaurin adsorbs almost completely in the interface. The addition of small amounts of ionic surfactant, regardless of the counterion, increases the solubilization of water in W/O microemulsions. The solubilization on oil in O/W microemulsions is not much affected, but structuring is induced and a viscous isotropic phase is formed. At high ionic surfactant concentrations, the single-phase microemulsion disappears and liquid crystals are favored.

  12. Effect of Cationic Surfactant Head Groups on Synthesis, Growth and Agglomeration Behavior of ZnS Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mehta SK

    2009-01-01

    Full Text Available Abstract Colloidal nanodispersions of ZnS have been prepared using aqueous micellar solution of two cationic surfactants of trimethylammonium/pyridinium series with different head groups i.e., cetyltrimethylammonium chloride (CTAC and cetyltrimethylpyridinium chloride (CPyC. The role of these surfactants in controlling size, agglomeration behavior and photophysical properties of ZnS nanoparticles has been discussed. UV–visible spectroscopy has been carried out for determination of optical band gap and size of ZnS nanoparticles. Transmission electron microscopy and dynamic light scattering were used to measure sizes and size distribution of ZnS nanoparticles. Powder X-ray analysis (Powder XRD reveals the cubic structure of nanocrystallite in powdered sample. The photoluminescence emission band exhibits red shift for ZnS nanoparticles in CTAC compared to those in CPyC. The aggregation behavior in two surfactants has been compared using turbidity measurements after redispersing the nanoparticles in water. In situ evolution and growth of ZnS nanoparticles in two different surfactants have been compared through time-dependent absorption behavior and UV irradiation studies. Electrical conductivity measurements reveal that CPyC micelles better stabilize the nanoparticles than that of CTAC.

  13. Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties

    DEFF Research Database (Denmark)

    Boutrup Stephansen, Karen; García-Díaz, María; Jessen, Flemming

    2016-01-01

    , and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties...... such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate......), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts...

  14. Relationship between Leadership Behaviors of High School Principals and Teacher Retention in Texas

    Science.gov (United States)

    Aiken, Debra L.

    2010-01-01

    The study investigated the relationship between leadership behaviors of high school principals and teacher retention in Texas. A total of 88 Texas high school principals participated in the survey. Leadership behaviors were measured using the Culturally Adapted Leadership for Inspired Business Excellence and Results (CALIBER) Leadership Assessment…

  15. Effect of surfactant species and electrophoretic medium composition on the electrophoretic behavior of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis.

    Science.gov (United States)

    Fukai, Nao; Kitagawa, Shinya; Ohtani, Hajime

    2017-07-01

    We have recently demonstrated the separation of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis (NACZE) using a cationic surfactant of cetyltrimethylammonium chloride (CTAC). In this study, eight ionic surfactants were investigated for the separation of four synthetic polymers (polystyrene, polymethylmethacrylates, polybutadiene, and polycarbonate); only three surfactants (CTAC, dimethyldioctadecylammonium bromide, and sodium dodecylsulfate) caused their separation. The order of the interaction between the polymers and the surfactants depended on both the surfactant species and the composition of the electrophoretic medium. Their investigation revealed that the separation is majorly affected by the hydrophobic interactions between the polymers and the ionic surfactants. In addition, the electrophoretic behavior of polycarbonate suggested that electrostatic interaction also affects the selectivity of the polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Officer and Enlisted Retention Behavior under Alternative Retirement Plans.

    Science.gov (United States)

    1980-12-01

    inflexibility and viewed as ineffective retention incentives for non-careerists. Although vesting priviledges provided transitional income, significant disparity...vesting priviledges after 10 years service. Severance payments were applied only to those leaving with 30 or more years service or those involuntarily...Time Retirement Begin Service You Retired Benefits Less than 10 $ 0 0% None 10 8,000 20.0% 65 years old 11 10,000 22.5% 65 12 12,000 25.0% 65 13

  17. Improving blood donor recruitment and retention: integrating theoretical advances from social and behavioral science research agendas.

    Science.gov (United States)

    Ferguson, Eamonn; France, Christopher R; Abraham, Charles; Ditto, Blaine; Sheeran, Paschal

    2007-11-01

    Increasing blood donor recruitment and retention is of key importance to transfusion services. Research within the social and behavioral science traditions has adopted separate but complementary approaches to addressing these issues. This article aims to review both of these types of literature, examine theoretical developments, identify commonalities, and offer a means to integrate these within a single intervention approach. The social and behavioral science literature on blood donor recruitment and retention focusing on theory, interventions, and integration is reviewed. The role of emotional regulation (anticipated anxiety and vasovagal reactions) is central to both the behavioral and the social science approaches to enhancing donor motivation, yet although intentions are the best predictor of donor behavior, interventions targeting enactment of intentions have not been used to increase donation. Implementation intentions (that is, if-then plans formed in advance of acting) provide a useful technique to integrate findings from social and behavioral sciences to increase donor recruitment and retention. After reviewing the literature, implementation intention formation is proposed as a technique to integrate the key findings and theories from the behavioral and social science literature on blood donor recruitment and retention.

  18. Predicting the Retention Behavior of Specific O-Linked Glycopeptides.

    Science.gov (United States)

    Badgett, Majors J; Boyes, Barry; Orlando, Ron

    2017-09-01

    O -Linked glycosylation is a common post-translational modification that can alter the overall structure, polarity, and function of proteins. Reverse-phase (RP) chromatography is the most common chromatographic approach to analyze O -glycosylated peptides and their unmodified counterparts, even though this approach often does not provide adequate separation of these two species. Hydrophilic interaction liquid chromatography (HILIC) can be a solution to this problem, as the polar glycan interacts with the polar stationary phase and potentially offers the ability to resolve the peptide from its modified form(s). In this paper, HILIC is used to separate peptides with O - N -acetylgalactosamine ( O -GalNAc), O - N -acetylglucosamine ( O -GlcNAc), and O -fucose additions from their native forms, and coefficients representing the extent of hydrophilicity were derived using linear regression analysis as a means to predict the retention times of peptides with these modifications.

  19. Hormonal contraceptive use and mate retention behavior in women and their male partners.

    Science.gov (United States)

    Welling, Lisa L M; Puts, David A; Roberts, S Craig; Little, Anthony C; Burriss, Robert P

    2012-01-01

    Female hormonal contraceptive use has been associated with a variety of physical and psychological side effects. Women who use hormonal contraceptives report more intense affective responses to partner infidelity and greater overall sexual jealousy than women not using hormonal contraceptives. Recently, researchers have found that using hormonal contraceptives with higher levels of synthetic estradiol, but not progestin, is associated with significantly higher levels of self-reported jealousy in women. Here, we extend these findings by examining the relationship between mate retention behavior in heterosexual women and their male partners and women's use of hormonal contraceptives. We find that women using hormonal contraceptives report more frequent use of mate retention tactics, specifically behaviors directed toward their partners (i.e., intersexual manipulations). Men partnered with women using hormonal contraceptives also report more frequent mate retention behavior, although this relationship may be confounded by relationship satisfaction. Additionally, among women using hormonal contraceptives, the dose of synthetic estradiol, but not of synthetic progesterone, positively predicts mate retention behavior frequency. These findings demonstrate how hormonal contraceptive use may influence behavior that directly affects the quality of romantic relationships as perceived by both female and male partners. Published by Elsevier Inc.

  20. Strategies for retaining study participants in behavioral intervention trials: retention experiences of the NIH Behavior Change Consortium.

    Science.gov (United States)

    Coday, Mace; Boutin-Foster, Carla; Goldman Sher, Tamara; Tennant, Jennifer; Greaney, Mary L; Saunders, Sandra D; Somes, Grant W

    2005-04-01

    Failing to retain an adequate number of study participants in behavioral intervention trials poses a threat to interpretation of study results and its external validity. This qualitative investigation describes the retention strategies promoted by the recruitment and retention committee of the Behavior Change Consortium, a group of 15 university-based sites funded by the National Institutes of Health to implement studies targeted toward disease prevention through behavior change. During biannual meetings, focus groups were conducted with all sites to determine barriers encountered in retaining study participants and strategies employed to address these barriers. All of the retention strategies reported were combined into 8 thematic retention categories. Those categories perceived to be most effective for retaining study participants were summarized and consistencies noted among site populations across the life course (e.g., older adults, adults, children, and adolescents). Further, possible discrepancies between site populations of varying health statuses are discussed, and an ecological framework is proposed for use in future investigations on retention.

  1. Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties.

    Science.gov (United States)

    Stephansen, Karen; García-Díaz, María; Jessen, Flemming; Chronakis, Ioannis S; Nielsen, Hanne M

    2016-03-07

    Intermolecular interaction phenomena occurring between endogenous compounds, such as proteins and bile salts, and electrospun compounds are so far unreported, despite the exposure of fibers to such biorelevant compounds when applied for biomedical purposes, e.g., tissue engineering, wound healing, and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts of insulin were released from the fibers when benzalkonium chloride was present. The FSP-Ins fibers appeared dense after incubation with this cationic surfactant, whereas high fiber porosity was observed after incubation with anionic or neutral surfactants. Contact angle measurements and staining with the hydrophobic dye 8-anilino-1-naphthalenesulfonic acid indicated that the FSP-Ins fibers were hydrophobic, and showed that the fiber surface properties were affected differently by the surfactants. Bovine serum albumin also affected insulin release in vitro, indicating that also proteins may affect the fiber performance in an in vivo setting.

  2. Retention behavior of flavonoids on immobilized artificial membrane chromatography and correlation with cell-based permeability.

    Science.gov (United States)

    Tsopelas, Fotios; Tsagkrasouli, Maria; Poursanidis, Pavlos; Pitsaki, Maria; Vasios, George; Danias, Panagiotis; Panderi, Irene; Tsantili-Kakoulidou, Anna; Giaginis, Constantinos

    2018-03-01

    The aim of the study was to investigate the immobilized artificial membrane (IAM) retention mechanism for a set of flavonoids and to evaluate the potential of IAM chromatography to model Caco-2 permeability. For this purpose, the retention behavior of 41 flavonoid analogs on two IAM stationary phases, IAM.PC.MG and IAM.PC.DD2, was investigated. Correlations between retention factors, logk w(IAM) and octanol-water partitioning (logP) were established and the role of hydroxyl groups of flavonoids to the underlying retention mechanism was explored. IAM retention and logP values were used to establish sound linear models with Caco-2 permeability (logP app ) taken from the literature. Both stepwise regression and multivariate analysis confirmed the contribution of hydrogen bond descriptors, as additional parameters in the either logk w(IAM) or logP models. Retention factors on both IAM stationary phases showed comparable performance with n-octanol-water partitioning towards Caco-2 permeability. Copyright © 2017 John Wiley & Sons, Ltd.

  3. Hybrid surfactants decorated with copper ions: aggregation behavior, antimicrobial activity and anti-proliferative effect.

    Science.gov (United States)

    Kaur, Gurpreet; Kumar, Sandeep; Dilbaghi, Neeraj; Bhanjana, Gaurav; Guru, Santosh Kumar; Bhushan, Shashi; Jaglan, Sundeep; Hassan, P A; Aswal, V K

    2016-09-14

    In the present study, the emphasis is laid on the self aggregation behavior of copper based inorganic-organic hybrids in aqueous media. The two complexes, cationic hexadecyl pyridinium trichloro cuprate (1 : 1), [Cp](+)[CuCl3](-), and bishexadecylpyridinium tetrachloro cuprate (2 : 1), [Cp2](2+)[CuCl4](2-), were synthesized using the ligand insertion method. The complexes were characterized using elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and thermogravimetric analysis. The copper complexes were found to be thermally stable, and in the solid state, they possessed the perovskite arrangement with [Cp2](2+)[CuCl4](2-) exhibiting superior stability and crystallinity. The self aggregation behavior of the prepared complexes was analyzed in solution phase (in aqueous medium) using surface tension, conductivity, XRD and small angle neutron scattering (SANS). The results show that the presence of copper as a co-ion in both the stoichiometries results in lower critical micellization concentrations than their precursor. Micellization was thermodynamically spontaneous and micelles formed were ellipsoidal in shape and underwent a prolate ellipsoidal growth with an increase in the concentration of metallosurfactant, as estimated from the SANS. Furthermore, these metallosurfactants were investigated for biocompatibility (using hemolytic assay), antimicrobial activity (fungus and bacteria) and cytotoxicity using human cancerous cells. The hemolysis activity was found to depend on the aggregated state of the metallosurfactants, displaying the highest activity in the monomeric state, and the minimum for post micellar concentrations. The surfactants were found to enhance the antibacterial activity by twofold or more, with the addition of metal in both the stoichiometries. On the contrary, for anticancer and antifungal activities, barely any regular trend or generalization could be obtained

  4. Retention behavior of double-crown attachments with zirconia primary and secondary crowns.

    Science.gov (United States)

    Schwindling, Franz Sebastian; Stober, Thomas; Rustemeier, Rainer; Schmitter, Marc; Rues, Stefan

    2016-05-01

    To investigate whether adequate retention of zirconia conical crown (CC) attachments can be achieved, and to investigate their long-term retention. Sixteen individual zirconia primary crowns were produced with convergence angles of 1° or 2° (eight of each). After determination of the convergence angles of the primary crowns, monolithic zirconia secondary crowns were manufactured. To evaluate the retention behavior of all-zirconia CC, the crowns were fitted with forces from F=12.5-100 N. Force magnitudes during the loosening process (L) were then measured. L/F ratios were recorded and the coefficient of friction (μ0) was calculated. Long-term retention was tested with up to 50,000 cycles of denture integration at a speed of 30 mms(-1) and a fitting force magnitude of 53 N. Even when primary crowns were manufactured with the utmost care, the real convergence angles were greater than the nominal angles of the standardized burs (1° and 2°) by 0.28° (SD 0.11°). Without mechanical aging, mean L/F was 0.632 (SD 0.038) for 1° samples and 0.526 (SD 0.022) for 2° samples, indicative of high retentive forces of up to 63.2% of the fitting forces. When all the test results were used, best-fitting curves gave μ0=0.117 for new samples and μ0=0.126 for samples after 50,000 integration cycles. When the correct milling and sintering parameters are chosen, the retention behavior of zirconia CCs is adequate and stable. This innovative type of attachment is appealing because of the beneficial properties of zirconia and the efficient CAD/CAM-based manufacture. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Polycyclic aromatic hydrocarbon behavior in bioactive soil slurry reactors amended with a nonionic surfactant.

    Science.gov (United States)

    Kim, Han S; Weber, Walter J

    2005-02-01

    The effects of an ethoxylated sorbitan fatty ester nonionic surfactant (Tween 80) on the bioavailability of polycyclic aromatic hydrocarbons (PAHs) were examined by using soil-free and dense-slurry (67% solids content, by wt) systems containing a creosote-contaminated field soil. The dispersed-micelle-phase PAHs in soil-free systems were not readily bioavailable to the mixed consortium of microbes indigenous to the creosote-contaminated soil. Instead, the microbes partially and preferentially utilized readily available portions of the surfactant as carbon sources (16-18% of the initial surfactant dose). This selective microbial attack resulted in destabilization of dispersed-phase micelles and significant decreases in molar solubilization ratio and micelle-water partition coefficient values. Remarkably high dosages (>20 g/L) of Tween 80 were required to enhance mobilization of the sorbed PAHs via micelle association because of the sorption of Tween 80 to the soil employed. The PAHs released from the destabilized micelles in soil-slurry systems either associated with sorbed-phase surfactants or readsorbed to soil organic matter too rapidly to be biologically accessed, even by the acclimated PAH-degrading microbes present. The work provides important new information and practical insights to surfactant solubilization and mobilization technology applications for the bioremediation of PAH-contaminated soils and sediments.

  6. Multiple Family Groups for Child Behavior Difficulties Retention Among Child Welfare-Involved Caregivers.

    Science.gov (United States)

    Gopalan, Geetha; Fuss, Ashley; Wisdom, Jennifer P

    2015-09-01

    Among children who remain at home with their permanent caregivers following a child welfare investigation, few who manifest emotional and behavioral difficulties actually engage in mental health treatment. The Multiple Family Group service delivery model to reduce childhood disruptive behavior disorders (MFG) has shown promise in engaging child welfare-involved families. This qualitative study examines caregiver perceptions of factors that influence retention in MFGs among child welfare-involved families. Twenty-five predominantly Black and Hispanic adult (ages 26-57) female caregivers with child welfare services involvement participated in individual, in-depth interviews about their experience with MFGs. Transcribed interview data were thematically coded guided by grounded theory methodology. Emergent themes were subsequently organized into a conceptual framework. Within the overarching influence of child welfare services involvement, specific components of MFGs influencing retention included the quality of interaction among group members, group facilitators' attentive approach with caregivers, supports designed to overcome logistical barriers (i.e., child care, transportation expenses, meals), and perceptions of MFG content and activities as fun and helpful. Caregiver factors, including their mental health and personal characteristics, as well as children's behavior, (i.e., observed changes in behavioral difficulties) were also associated with retention. High acceptability suggest utility for implementing MFGs within settings serving child welfare involved families, with additional modifications to tailor to setting and client features.

  7. Optimization of Surfactant Mixtures and Their Interfacial Behavior for Advanced Oil Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Somasundaran, Prof. P.

    2002-03-04

    The objective of this project was to develop a knowledge base that is helpful for the design of improved processes for mobilizing and producing oil left untapped using conventional techniques. The main goal was to develop and evaluate mixtures of new or modified surfactants for improved oil recovery. In this regard, interfacial properties of novel biodegradable n-alkyl pyrrolidones and sugar-based surfactants have been studied systematically. Emphasis was on designing cost-effective processes compatible with existing conditions and operations in addition to ensuring minimal reagent loss.

  8. Chemical states and deuterium retention behavior of vacuum plasma sprayed tungsten coatings

    International Nuclear Information System (INIS)

    Niu Yaran; Suzuki, Sachiko; Zheng Xuebin; Ding Chuanxian; Chen Junling; Wang Wanjing; Oya, Yasuhisa; Okuno, Kenji

    2011-01-01

    Tungsten (W) coatings were prepared using vacuum plasma spraying (VPS) technology and then the chemical states and retention behaviors of deuterium in VPS-W coatings were analyzed by X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). The results showed that chemical reacted oxygen (W-O bonds) and chemisorbed oxygen (O-O bonds) existed both on the surface and interior of tungsten coatings. Oxygen was chemically sputtered during D 2 + implantation. Two deuterium desorption stages at the temperature ranges around 300-700 K and 800-1150 K were observed for tungsten coatings. The retention behavior of deuterium in tungsten coatings was greatly different from that of bulk tungsten, which was related to the existence of oxygen.

  9. A study of the relationship between surfactant/oil/brine system phase behavior and chemical flood recovery in short cores

    Energy Technology Data Exchange (ETDEWEB)

    Ashrawi, S.S.

    1984-04-01

    This study correlates the phase behavior of surfactant/oil/brine systems with their chemical flood performance in short cores. The study focuses on the influence of two important system composition variables: viz. the brine salinity and the nominal equivalent weight of a petroleum sulfonate blend. Furthermore, it investigates the influence of the addition of an alkylether sulfate in terms of optimal salinities, increased salinity tolerance and tertiary recovery efficiency. The oil displacement experiments employ a very fast, near-continuous, constant salinity flooding process in 3-inch long Berea cores, using a microwave instrument to determine the oil saturations. A typical turn-around time for a flooding experiment was seven hours.

  10. Fouling behavior of silica nanoparticle-surfactant mixtures during constant flux dead-end ultrafiltration

    NARCIS (Netherlands)

    Trzaskus, Krzystof; Lee, Sooi Li; de Vos, Wiebe Matthijs; Kemperman, Antonius J.B.; Nijmeijer, Kitty

    2017-01-01

    The increasing use of engineered nanoparticles in customer products results in their accumulation in water sources. In this experimental study, we investigated the role of surfactant type (cationic, anionic and non-ionic) and concentration on fouling development, nanoparticle rejection and fouling

  11. Magnetic surfactants

    OpenAIRE

    Brown, P.; Alan Hatton, T.; Eastoe, J.

    2015-01-01

    Surfactants are ubiquitous, being important commodity chemicals with wide industrial applications, and essential components of living organisms. With stimuli-responsive surfactants, self-assembly and physicochemical properties of a wide variety of materials may be readily manipulated, both reversibly and irreversibly. Until recently, magnetically responsive surfactants had not been reported. This review reports the recent progress in magnetoresponsive surfactants, covering control of interfac...

  12. Effects of temperature on the rheological behavior of worm-like micelles in a mixed nonionic surfactant system.

    Science.gov (United States)

    Hashizaki, Kaname; Taguchi, Hiroyuki; Saito, Yoshihiro

    2009-01-01

    We examined the effects of temperature on the rheological behavior of worm-like micelles in a nonionic surfactant system consisting of polyoxyethylene (10) phytosterol (PhyEO(10))/glyceryl monocaprylate (GFA-C(8))/Water. First, the phase diagram of a PhyEO(10)/GFA-C(8)/Water system was examined when the weight ratio, R, of GFA-C(8) to the total surfactants was changed keeping the total concentration of the surfactants at 5 wt%. The formation of worm-like micelles was confirmed over a wide temperature range. Next, the effect of temperature on the rheological properties of the worm-like micelles was examined. From steady-flow viscosity measurements of the worm-like micelles, it was found that the zero-shear viscosity (eta(0)) gave a maximum value more than 1,000 times greater than the minimum value in the temperature range 20-50 degrees C. Further, the temperature at which the maximum eta(0) was observed decreased with increasing R value. These results indicate that there is an optimal temperature at which the entanglement of worm-like micelles is at its greatest. From dynamic viscoelasticity measurements, it was shown that the viscoelastic behavior observed for the worm-like micelles was consistent with the Maxwell model, which is the basic model for a viscoelastic body. In addition, the plateau modulus (G(0)), which reflects the volume fraction of entangled worm-like micelles, gradually increased with increasing temperature, while the relaxation time (tau), which reflects the disentanglement time of the worm-like micelles, rapidly decreased with increasing temperature. From these results, it was clarified that, for a nonionic worm-like micelle, tau influences the change in eta(0) more strongly than G(0).

  13. Nonlinear Surface Dilatational Rheology and Foaming Behavior of Protein and Protein Fibrillar Aggregates in the Presence of Natural Surfactant.

    Science.gov (United States)

    Wan, Zhili; Yang, Xiaoquan; Sagis, Leonard M C

    2016-04-19

    The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein-surfactant interfacial interactions. The adsorption at, and nonlinear dilatational rheological behavior of, the air-water interface were studied by combining drop shape analysis tensiometry, ellipsometry, and large-amplitude oscillatory dilatational rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. The heat treatment generates a mixture of long fibrils and unconverted peptides. The presence of small peptides in 11S fibril samples resulted in a faster adsorption kinetics than that of native 11S. The addition of STE affected the adsorption of 11S significantly, whereas no apparent effect on the adsorption of the 11S fibril-peptide system was observed. The rheological response of interfaces stabilized by 11S-STE mixtures also differed significantly from the response for 11S fibril-peptide-STE mixtures. For 11S, the STE reduces the degree of strain hardening in extension and increases strain hardening in compression, suggesting the interfacial structure may change from a surface gel to a mixed phase of protein patches and STE domains. The foams generated from the mixtures displayed comparable foam stability to that of pure 11S. For 11S fibril-peptide mixtures STE only significantly affects the response in extension, where the degree of strain softening is decreased compared to the pure fibril-peptide system. The foam stability of the fibril-peptide system was significantly reduced by STE. These findings indicate that fibrillization of globular proteins could be a potential strategy to modify the complex surface and foaming behaviors of protein-surfactant mixtures.

  14. Effect of surfactant Te on the behavior of alumina inclusions at advancing solid-liquid interfaces of liquid steel

    International Nuclear Information System (INIS)

    Zheng, Lichun; Malfliet, Annelies; Wollants, Patrick; Blanpain, Bart; Guo, Muxing

    2016-01-01

    The effect of surfactant Te on the behavior of alumina inclusions at advancing solid-liquid interfaces of liquid steel was studied by adding Te to liquid steel before Al deoxidation at 1873 K. After water-quenching, the spatial distribution homogeneity of alumina inclusions in the steel matrix was characterized using the Dirichlet tessellation method. The deterioration of this homogeneity with increasing the addition of Te indicates that Te facilitates pushing of alumina inclusions. This phenomenon was discussed based on the thermodynamics of an asymmetric thin liquid film confined by an advancing solid-liquid interface and a particle. The surface excesses of Te at the solid-liquid and particle-liquid interfaces were theoretically demonstrated to decrease when an alumina inclusion moves towards the solid-liquid interface, thereby weakening the effect of Te on the solid-liquid and particle-liquid interfacial energies. Based on this, effect of surfactants was incorporated in the models predicting the critical velocity V C .

  15. Optimization of Surfactant Mixtures and Their Interfacial Behavior for Advanced Oil Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Somasundaran, Prof. P.

    2001-02-27

    The goal of this report is to develop improved extraction processes to mobilize and produce the oil left untapped using conventional techniques. Current chemical schemes for recovering the residual oil have been in general less than satisfactory. High cost of the processes as well as significant loss of chemicals by adsorption on reservoir materials and precipitation has limited the utility of chemical-flooding operations. There is a need to develop cost-effective, improved reagent schemes to increase recovery from domestic oil reservoirs. The goal of the report was to develop and evaluate novel mixtures of surfactants for improved oil recovery.

  16. [Retention behavior of solutes on liquid chromatographic column packed with dynamically modified zirconia].

    Science.gov (United States)

    Zhang, Q; Feng, Y; Yan, L; Da, S

    1999-05-01

    Zirconia was dynamically modified with stearic acid, beta-cyclodextrin and sodium dodecylsulfonate, separately, to form liquid chromatographic packings. The chromatographic behaviors of aromatic hydrocarbons, acidic compounds (phenol, nitrophenols and benzoic acids) and basic compounds (aniline, nitroanilines and toluidines) were investigated on these modified zirconia packings with a mixture of methanol/water as the mobile phase. On stearic acid modified zirconia, aromatic hydrocarbons and the basic compounds exhibit symmetrical peaks. The retention time of these solutes decreases with increasing the concentration of methanol in the mobile phase. When the mobile phases with stearic acid were used, the retention time of these solutes has a maximum with variation of stearic acid concentration (0-1.0 mmol/L) in the mobile phase. However, the acidic compounds such as nitrophenols and benzoic acids are strongly adsorbed and can not be eluted from the column with the mobile phases. No leaking of stearic acid on the modified zirconia was found after 3000 column volumes of the methanol/water mobile phase were used. The results showed that the stearic acid modified zirconia can be used as a stationary phase for reversed-phase liquid chromatography. On beta-cyclodextrin modified zirconia, aromatic hydrocarbons and basic compounds exhibit shorter retention time than those on the stearic acid modified zirconia under the same mobile phase composition, however, nitrophenols can be eluted but give unsymmetrical peaks. On sodium dodecylsulfonate modified zirconia packings, the basic compounds can not be retarded; Aromatic hydrocarbons and acidic compounds exhibit short retention time. The results can be ascribed to the weak adsorption of sodium dodecylsulfonate on the zirconia.

  17. Transient behavior of simultaneous flow of gas and surfactant solution in consolidated porous media

    Energy Technology Data Exchange (ETDEWEB)

    Baghdikian, S.Y.; Handy, L.L.

    1991-07-01

    The main objective of this experimental research was to investigate the mechanisms of foam generation and propagation in porous media. Results obtained give an insight into the conditions of foam generation and propagation in porous media. The rate of propagation of foam is determined by the rates of lamellae generation, destruction, and trapping. Several of the factors that contribute to foam generation have studied with Chevron Chaser SD1000 surfactant. Interfacial tension (IFT) measurements were performed using a spinning drop apparatus. The IFT of two surfactant samples of different concentrations were measured with dodecane and crude oil from the Huntington Beach Field as a function of temperature and time. Foam was used as an oil-displacing fluid. However, when displacing oil, foam was not any more effective than simultaneous brine and gas injection. A series of experiments was performed to study the conditions of foam generation in Berea sandstone cores. Results show that foam may be generated in sandstone at low flow velocities after extended incubation periods. The effect of pregenerating foam before injection into the sandstone was also studied. The pressure profiles in the core were monitored using three pressure taps along the length of the core. A systematic study of foaming with different fluid velocities and foam qualities provides extensive data for foam flow conditions. 134 refs., 57 figs., 2 tabs.

  18. Phase behavior of aqueous two-phase systems of cationic and anionic surfactants and their application to theanine extraction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Junwei; Wang, Yan; Peng, Qijun [Jiangnan University, Wuxi (China)

    2013-06-15

    Phase behavior of aqueous two-phase systems (ATPS) containing cationic (SDS) and anionic (CTAB) surfactants and its application to theanine extraction was studied. Results indicated the ATPS could form under the certain SDS/CTAB molar ratio; there was a reasonable consistency between the conductivity and the formation region of ATPS, and the viscosity was higher in the formation region of ATPS. Additionally, the phase ratio increased with increase of CATB concentration, and the interfacial film between the top phase and the bottom phase was resilient. Moreover, the theanine extraction with ATPS was realized in the waste liquid of tea polyphenol production (WLTPP), and the partition coefficient of theanine decreased with increase of WLTPP concentration, whereas the extraction rate of theanine increased. The partition coefficient decreased with increasing SDS/CTAB molar ratio, and the extraction rate of theanine increased with increase of SDS/CTAB molar ratio.

  19. Critical Role of the Spacer Length of Gemini Surfactants on the Formation of Ionic Liquid Crystals and Thermotropic Behavior.

    Science.gov (United States)

    Fernandes, Ricardo M F; Wang, Yujie; Tavares, Pedro B; Nunes, Sandra C C; Pais, Alberto A C C; Marques, Eduardo F

    2017-11-22

    Numerous reports have shown that the self-assembling properties of 12-s-12 bis(quaternary ammonium) gemini surfactants in aqueous solution are significantly influenced by s, the number of methylene groups in the covalent spacer. However, the role played by s on the phase behavior of the single compounds has not been investigated in a similarly systematic way. Here, we report on the thermotropic phase behavior of the anhydrous compounds with s = 2-6, 8, 10, and 12, resorting to differential scanning calorimetry (DSC), polarized light microscopy (PLM), and X-ray diffraction (XRD). All of the compounds show a stepwise melting behavior, decomposing at 200 °C. As the spacer length increases, nonmonotonic trends are observed for the thermodynamic parameters of the thermotropic phase transitions, mesophase formation, and solid-state d 00l spacings. In particular, the number and type of mesophases (ordered smectic phases and/or fluid smectic liquid crystals) depend critically on s. Further, upon heating molecules with s liquid phase, while those with long spacers, s = 8-12, reach the isotropization (clearing) temperature, hence forming both ionic liquid crystals and ionic liquid phases. We demonstrate that the melting behavior and type of ionic mesophases formed by gemini molecules can be usefully manipulated by a simple structural parameter like the length of the covalent linker.

  20. Gas retention and release behavior in Hanford double-shell waste tanks

    International Nuclear Information System (INIS)

    Meyer, P.A.; Brewster, M.E.; Bryan, S.A.

    1997-05-01

    This report describes the current understanding of flammable gas retention and release in Hanford double-shell waste tanks AN-103, AN-104, AN-105, AW-101, SY-101, and SY-103. This knowledge is based on analyses, experimental results, and observations of tank behavior. The applicable data available from the void fraction instrument, retained gas sampler, ball rheometer, tank characterization, and field monitoring are summarized. Retained gas volumes and void fractions are updated with these new data. Using the retained gas compositions from the retained gas sampler, peak dome pressures during a gas burn are calculated as a function of the fraction of retained gas hypothetically released instantaneously into the tank head space. Models and criteria are given for gas generation, initiation of buoyant displacement, and resulting gas release; and predictions are compared with observed tank behavior

  1. Improving utilization of and retention in PMTCT services: can behavioral economics help?

    Science.gov (United States)

    Taylor, Nicholas Kenji; Buttenheim, Alison M

    2013-10-10

    The most recent strategic call to action of the World Health Organization sets the elimination of pediatric HIV as a goal. While recent efforts have focused on building infrastructure and ensuring access to high-quality treatment, we must now turn our focus to the behavior change needed to eliminate vertical transmission. We make the case for the application of concepts from the field of behavioral economics to prevention of mother-to-child transmission (PMTCT) programs to more effectively address demand-side issues of uptake and retention. We introduce five concepts from the field of behavioral economics and discuss their application to PMTCT programs: 1) Mentor mothers who come from similar circumstances as PMTCT patients can serve as social references who provide temporally salient modeling of utilization of services and adherence to treatment. 2) Economic incentives, like cell phone minutes or food vouchers, that reward adherence to PMTCT protocols leverage present bias, the observation that people are generally biased toward immediate versus future awards. 3) Default bias, our preference for the default option, is already being used in many countries in the form of opt-out testing, and could be expanded to all PMTCT programs. 4) We are hardwired to avoid loss more than to pursue an equivalent gain. PMTCT programs can take advantage of loss aversion through the use of commitment contracts that incentivize mothers to return to the clinic in order to avoid both reputational and financial loss. Eliminating vertical transmission of HIV is an ambitious goal. To close the remaining gap, innovations are needed to address demand for PMTCT services. Behavioral economics offers a set of tools that can be engineered into PMTCT programs to increase uptake and improve retention with minimal investment.

  2. Corrosion behavior of dental alloys used for retention elements in prosthodontics.

    Science.gov (United States)

    Nierlich, Judith; Papageorgiou, Spyridon N; Bourauel, Christoph; Hültenschmidt, Robert; Bayer, Stefan; Stark, Helmut; Keilig, Ludger

    2016-06-01

    The purpose of this study was to investigate the corrosion behavior of 10 different high noble gold-based dental alloys, used for prosthodontic retention elements, according to ISO 10271. Samples of 10 high-noble and noble gold-based dental alloys were subjected to: (i) static immersion tests with subsequent analysis of ion release for eight different elements using mass spectrometry; (ii) electrochemical tests, including open-circuit potential and potentiodynamic scans; and (iii) scanning electron microscopy, followed by energy-dispersive X-ray microscopy. The results were analyzed using one-way ANOVA and Sidak multiple-comparisons post-hoc test at a level of significance of α = 0.05. Significant differences were found among the 10 alloys studied for all ions (P alloys. Scanning electron microscopy analysis confirmed the existence of typically small-diameter corrosion defects, whilst the energy-dispersive X-ray analysis found no significant alteration in the elemental composition of the alloys. The results of this study reveal the variability in the corrosive resistance among the materials used for retention elements in prosthodontics. © 2016 Eur J Oral Sci.

  3. Maternal behavioral factors influencing postpartum weight retention. Clinical and metabolic implications

    Directory of Open Access Journals (Sweden)

    Mariana A. Falivene

    Full Text Available Abstract Objectives: to describe some factors of maternal behavior such as breastfeeding, diet, physical activity, sleep and clinical-metabolic disorders associated with retention and/or weight gain during postpartum. Methods: specific articles on the subject were searched in LILACS, MEDLINE/PubMed and SciELO databases. Results: the literature review suggests that breastfeeding or physical activity alone are not enough to return to the pre-pregnancy weight, if they are not combined with restrictions of energy intake. Reduced sleep affects both eating habits and activity patterns resulting in lower energy expenditure, in addition to altering the glycemic metabolism. Conclusions: maternal obesity increases the risk of metabolic syndrome. Interventions during postpartum are critical for maternal health and could be the key in reducing the risk of transgenerational maternal/childhood obesity.

  4. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Prof. P. Somasundaran

    2002-09-30

    The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Surfactant loss by adsorption or precipitation depends to a great extent on the type of surfactant complexes and aggregates formed. Such information as well as techniques to generate the information is lacking currently particularly for surfactant mixtures and surfactant/polymer systems. A novel analytical centrifuge application is explored during the last period to generate information on structures-performance relationship for different surfactant aggregates in solution and, in turn, at interfaces. To use analytical untracentrifuge for surfactant mixtures, information on partial specific volumes of single surfactants and their mixtures is required. Towards this purpose, surface tension and density measurements were performed to determine critical micellar concentrations (cmc), partial specific volumes of n-dodecyl-{beta}-Dmaltoside (DM), nonyl phenol ethoxylated decyl ether (NP-10) and their 1:1 mixtures at 25 C. Durchschlag's theoretical calculation method was adopted to calculate the partial specific volumes. Effects of temperature and mixing, as well as methods used for estimation on micellization and partial specific volumes were studied during the current period. Surface tension results revealed no interaction between the two surfactants in mixed micelles. Partial specific volume measurements also indicated no interaction in mixed micelles. Maximum adsorption density, area per molecule and free energy of micellization were also calculated. Partial specific volumes were estimated by two experimental methods: d{sub {rho}}/dc and V{sub {sigma}}. The difference between the results of using the two methods is within 0.5% deviation. It was found that the partial specific volume is concentration dependent and sensitive to changes in temperature. The information generated in this study will be used for the study of surfactant aggregate mass

  5. Behavior of microemulsion systems of virgin coconut oil (VCO) using igepal CO-520 and tween 80 surfactant

    Science.gov (United States)

    Safuan, A.; Hamdan, S.; Laili, C. R.

    2017-09-01

    Virgin Coconut Oil (VCO) has been applied in many application and products. Formation of microemulsion region with surfactant was investigated by using phase diagram. The surfactants used are igepal CO-520 and tween 80. The studies showed that formation of microemulsion region were dependent on the behaviour of the surfactant toward VCO. The result showed that microemulsion regions were present in igepal CO-520 system formed a larger water-in-oil microemulsion region compared to tween 80 system. Certain weight ratios of VCO to surfactants were studied by using evaporation test in order to study the water loss of the microemulsion in ambient condition. The evaporation rate of samples was varies depending their compositon of VCO, surfactant and water.

  6. Recruitment and Retention of South Asian Ethnic Minority Populations in Behavioral Interventions to Improve Type 2 Diabetes Outcomes.

    Science.gov (United States)

    Mahmood, Bushra; Afshar, Rowshanak; Tang, Tricia S

    2017-04-01

    South Asian (SA) immigrants have a higher burden of type 2 diabetes, report poor self-management, and remain a hard-to-engage group in behavioral interventions. The purpose of this review was to characterize recruitment and retention of SAs in behavioral interventions. We identified 14 studies with limited information regarding recruitment and retention. Overall recruitment rates were low: 12 studies had a mean recruitment rate of 44% among those screened, and 9 studies with complete information on eligibility had a mean recruitment rate of 65.8% among those eligible. Mean retention rate was 79.4% across all 14 studies. Although unstandardized and inconsistent reporting limited our ability to draw any conclusions regarding the best strategies to maximize recruitment and retention, we were able to highlight some novel and effective strategies. There is a need for consistent and standardized reporting of recruitment and retention-related information to encourage meaningful research and guide researchers in efficient allocation of resources and a successful conclusion of future interventions.

  7. Effect of surfactant on porosity and swelling behaviors of guar gum-g-poly(sodium acrylate-co-styrene)/attapulgite superabsorbent hydrogels.

    Science.gov (United States)

    Shi, Xiao-Ning; Wang, Wen-Bo; Wang, Ai-Qin

    2011-11-01

    Novel fast-swelling porous guar gum-g-poly(sodium acrylate-co-styrene)/attapulgite (GG-g-P(NaA-co-St)/APT) superabsorbent hydrogels were prepared by simultaneous free-radical graft copolymerization reaction of guar gum (GG), partially neutralized AA (NaA), styrene (St) and attapulgite (APT) using N,N'-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution and the surfactant self-assembling templating pore-forming technique. Fourier transform infrared (FTIR) spectroscopy confirmed that the surfactant could be removed from the final hydrogel product by methanol/water (8:1, v/v) washing process and the surfactant only act as micelle template to form pores. The effect of surfactant type on the porous microstructure of the hydrogel was assessed by field emission scanning electron microscope (FESEM). It was shown that incorporation of proper amount of anionic surfactant sodium n-dodecyl sulfate (SDS) in the gelling process of the hydrogel can obviously enhance the swelling capacity and initial swelling rate. The salt-sensitivity of the SDS-added hydrogel in distilled water and 15 mmol/L NaCl, CaCl(2) solution or 15 mmol/L NaCl and CaCl(2) solution was investigated, and it was found that the swelling-deswelling capability is quite reversible. A similar reproducible on-off switching behavior was observed in the 1 mmol/L solution of phosphate buffer at pH 2.1 and 7.4. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Feasibility of dialectical behavior therapy with suicidal and self-harming adolescents with multi-problems: training, adherence, and retention.

    Science.gov (United States)

    Tørmoen, A J; Grøholt, B; Haga, E; Brager-Larsen, A; Miller, A; Walby, F; Stanley, B; Mehlum, L

    2014-01-01

    We evaluated the feasibility of DBT training, adherence, and retention preparing for a randomized controlled trial of Dialectical Behavior Therapy (DBT) adapted for Norwegian adolescents engaging in self-harming behavior and diagnosed with features of borderline personality disorder. Therapists were intensively trained and evaluated for adherence. Adherence scores, treatment retention, and present and previous self-harm were assessed. Twenty-seven patients were included (mean age 15.7 years), all of them with recent self-harming behaviors and at least 3 features of Borderline Personality Disorder. Therapists were adherent and 21 (78%) patients completed the whole treatment. Three subjects reported self-harm at the end of treatment, and urges to self-harm decreased. At follow up, 7 of 10 subjects reported no self-harm. DBT was found to be well accepted and feasible. Randomized controlled trials are required to test the effectiveness of DBT for adolescents.

  9. Theoretical analysis of the retention behavior of alcohols in gas chromatography.

    Science.gov (United States)

    Song, Yuanzhi; Zhou, Jianfeng; Zi, Sanjun; Xie, Jiming; Ye, Yong

    2005-05-02

    Quantitative structure-retention relationship (QSRR) models for the chromatographic (GC) retention times of alcohols on Superox 20M-diglycerol polarity stationary phase have been developed. Semi-empirical quantum chemical method (AM1) in MOPAC and Hartree-Fock (HF) method in Gaussian 98 implemented were employed to calculate a set of molecular descriptors of alcohols and ethyl acetate. Using multiple linear regression (MLR), we obtained the empirical functions with high correlation coefficient between retention times and quantum-chemical descriptors. The retention mechanism of alcohols of separation operating in the gas chromatogram was discussed. The results indicated that the QSRR models proposed were satisfactory.

  10. In vivo corrosion behavior of gold-plated versus titanium dental retention pins.

    Science.gov (United States)

    Palaghias, G; Eliades, G; Vougiouklakis, G

    1992-02-01

    Two types of titanium dental retention pins and a gold-plated stainless steel pin were tested for their in vivo corrosion behavior. Six paired samples of titanium and gold-plated pins were placed in box preparations of 12 periodontally involved premolars. Half of the samples were restored with a high copper admixed type amalgam while the rest were restored with a BisGMA-POCl2 bonding resin and a hybrid visible light-cured composite resin. After 3 months in vivo, the teeth were extracted, and the pins were removed and examined with an electron microprobe. The surface of the titanium pins was found to be smooth and without defects. Only traces of Ca and P could be identified from dentin. The gold-plated pins demonstrated cracks and pores, especially at the outer part of the serrations, resulting in disruption of the electroplated film. Traces of Hg, Sn, Cu, S, Zn, Ca, K, Cl, P, and S were detected at the gold-plated pin/amalgam interface, while Cl and P were found at the gold-plated pin/composite resin interface. The in vivo corrosion resistance of the titanium pins was found to be superior to that of the gold-plated stainless steel pins.

  11. Gas retention and release behavior in Hanford single-shell waste tanks

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, C.W.; Brewster, M.E.; Gauglitz, P.A.; Mahoney, L.A.; Meyer, P.A.; Recknagle, K.P.; Reid, H.C.

    1996-12-01

    This report describes the current understanding of flammable gas retention and release in Hanford single-shell waste tanks based on theory, experimental results, and observations of tank behavior. The single-shell tanks likely to pose a flammable gas hazard are listed and described, and photographs of core extrusions and the waste surface are included. The credible mechanisms for significant flammable gas releases are described, and release volumes and rates are quantified as much as possible. The only mechanism demonstrably capable of producing large ({approximately}100 m{sup 3}) spontaneous gas releases is the buoyant displacement, which occurs only in tanks with a relatively deep layer of supernatant liquid. Only the double-shell tanks currently satisfy this condition. All release mechanisms believed plausible in single-shell tanks have been investigated, and none have the potential for large spontaneous gas releases. Only small spontaneous gas releases of several cubic meters are likely by these mechanisms. The reasons several other postulated gas release mechanisms are implausible or incredible are also given.

  12. Gas retention and release behavior in Hanford single-shell waste tanks

    International Nuclear Information System (INIS)

    Stewart, C.W.; Brewster, M.E.; Gauglitz, P.A.; Mahoney, L.A.; Meyer, P.A.; Recknagle, K.P.; Reid, H.C.

    1996-12-01

    This report describes the current understanding of flammable gas retention and release in Hanford single-shell waste tanks based on theory, experimental results, and observations of tank behavior. The single-shell tanks likely to pose a flammable gas hazard are listed and described, and photographs of core extrusions and the waste surface are included. The credible mechanisms for significant flammable gas releases are described, and release volumes and rates are quantified as much as possible. The only mechanism demonstrably capable of producing large (∼100 m 3 ) spontaneous gas releases is the buoyant displacement, which occurs only in tanks with a relatively deep layer of supernatant liquid. Only the double-shell tanks currently satisfy this condition. All release mechanisms believed plausible in single-shell tanks have been investigated, and none have the potential for large spontaneous gas releases. Only small spontaneous gas releases of several cubic meters are likely by these mechanisms. The reasons several other postulated gas release mechanisms are implausible or incredible are also given

  13. Retention behavior of lipids in reversed-phase ultrahigh-performance liquid chromatography-electrospray ionization mass spectrometry.

    Science.gov (United States)

    Ovčačíková, Magdaléna; Lísa, Miroslav; Cífková, Eva; Holčapek, Michal

    2016-06-10

    Reversed-phase ultrahigh-performance liquid chromatography (RP-UHPLC) method using two 15cm sub-2μm particles octadecylsilica gel columns is developed with the goal to separate and unambiguously identify a large number of lipid species in biological samples. The identification is performed by the coupling with high-resolution tandem mass spectrometry (MS/MS) using quadrupole - time-of-flight (QTOF) instrument. Electrospray ionization (ESI) full scan and tandem mass spectra are measured in both polarity modes with the mass accuracy better than 5ppm, which provides a high confidence of lipid identification. Over 400 lipid species covering 14 polar and nonpolar lipid classes from 5 lipid categories are identified in total lipid extracts of human plasma, human urine and porcine brain. The general dependences of relative retention times on relative carbon number or relative double bond number are constructed and fit with the second degree polynomial regression. The regular retention patterns in homologous lipid series provide additional identification point for UHPLC/MS lipidomic analysis, which increases the confidence of lipid identification. The reprocessing of previously published data by our and other groups measured in the RP mode and ultrahigh-performance supercritical fluid chromatography on the silica column shows more generic applicability of the polynomial regression for the description of retention behavior and the prediction of retention times. The novelty of this work is the characterization of general trends in the retention behavior of lipids within logical series with constant fatty acyl length or double bond number, which may be used as an additional criterion to increase the confidence of lipid identification. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Retention and wear behaviors of two implant overdenture stud-type attachments at different implant angulations.

    Science.gov (United States)

    Choi, Jae-Won; Bae, Ji-Hyeon; Jeong, Chang-Mo; Huh, Jung-Bo

    2017-05-01

    Implant angulation should be considered when selecting an attachment. Some in vitro studies have investigated the relationship between implant angulation and changes in the retention force of the stud attachment, but few studies have evaluated the effect of cyclic loading and repeated cycles of insertion and removal on the stud attachment. The purpose of this in vitro study was to evaluate the effects of implant angulation on the retentive characteristics of overdentures with 2 different stud attachments, an experimental system and O-rings in red and orange, after cyclic loading and repeated insertion and removal cycles. The canine region of a mandibular experimental model was fitted with 2 implant fixtures with 2 different stud attachment systems at implant angulations of 0, 15, or 30 degrees. A mastication simulator was used to simulate cyclic loading, and a universal testing machine was used to evaluate retentive force changes after repeated insertion and removal cycles. To simulate the numbers of mastication and insertion and removal cycles per annum, 400000 cyclic loadings and 1080 insertion and removal cycles were performed. Wear patterns and attachment surface deformations were evaluated by scanning electron microscopy. Data were analyzed using the Kruskal-Wallis test, Mann-Whitney U test with Bonferroni correction (α=.05/3=.017), and the paired-sample Student t test (α=.05). When retentive forces before and after testing were compared, O-ring showed significant retention loss at all implant angulations (P.05), whereas the 30-degree model showed a significant increase in retentive force (P=.001). At all implant angulations, retention loss increased significantly for the orange O-ring, followed by the red O-ring, and the experimental system (Pattachment systems. Even when implants are not installed in parallel, the experimental system can be used without involving great loss of retention. Copyright © 2016 Editorial Council for the Journal of Prosthetic

  15. Confinement-induced phase behavior and adsorption regulation of ionic surfactants in the aqueous film between charged solids

    NARCIS (Netherlands)

    Lokar, W.J.; Koopal, L.K.; Leermakers, F.A.M.; Ducker, W.A.

    2004-01-01

    The adsorption of an ionic surfactants in the aqueous film between charged solids was calculated using self-consistent field theory for adsorption and association. It was shown that a change in the separation between the solids leads to a change in interaction energy, which leads to a change in both

  16. Retention behavior of selected alkaloids in Reversed Phase micellar chromatographic systems

    Directory of Open Access Journals (Sweden)

    Petruczynik Anna

    2015-06-01

    Full Text Available In this work, the effects of sodium dodecyl sulfate (SDS concentrations on retention, separation selectivity, peak shapes and systems efficiency were investigated. Herein, the retention data for 11 alkaloids were determined on an RP18 silica column with mobile phases containing methanol as organic modifier, with acetate buffer at pH 3.5, and, subsequently, with the addition of sodium dodecyl sulfate (SDS. The results of this study indicate that the retention of alkaloids decreases with the increase of SDS concentration in the mobile phase. The increase of SDS concentration, however, leads to the significantly improvement of peak symmetry and the increase of theoretical plate number in all cases. The best system efficiency for most of the investigated alkaloids was obtained in a mobile phase containing 0.1 M SDS, while most symmetrical peaks were obtained through the addition of 0.3 M of SDS to the mobile phase.

  17. Characterizing adsorption of associating surfactants on carbonates surfaces.

    Science.gov (United States)

    Jian, Guoqing; Puerto, Maura; Wehowsky, Anna; Miller, Clarence; Hirasaki, George J; Biswal, Sibani L

    2018-03-01

    The adsorption of anionic surfactants onto positively charged carbonate minerals is typically high due to electrostatic interactions. By blending anionic surfactants with cationic or zwitterionic surfactants, which naturally form surfactant complexes, surfactant adsorption is expected to be influenced by a competition between surfactant complexes and surfactant-surface interactions. The adsorption behavior of surfactant blends known to form complexes was investigated. The surfactants probed include an anionic C 15-18 internal olefin sulfonate (IOS), a zwitterionic lauryl betaine (LB), and an anionic C 13 -alcohol polyethylene glycol ether carboxylic acid (L38). An analytical method based on high-performance liquid chromatography evaporative light scattering detector (HPLC-ELSD) was developed to measure three individual surfactant concentrations from a blended surfactant solution. The adsorption of the individual surfactants and surfactant blends were systematically investigated on different mineral surfaces using varying brine solutions. LB adsorption on calcite surfaces was found to be significantly increased when blended with IOS or L38 since it forms surfactant complexes that partition to the surface. However, the total adsorption of the LB-IOS-L38 solution on dolomite decreased from 3.09 mg/m 2 to 1.97 mg/m 2 when blended together compared to summing the adsorption values of individual surfactants, which highlights the importance of mixed surfactant association. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Swimming behavior and prey retention of the polychaete larvae Polydora ciliata (Johnston)

    DEFF Research Database (Denmark)

    Hansen, B.W.; Jakobsen, Hans Henrik; Andersen, Anders Peter

    2010-01-01

    that feed without trailing threads. We observed bell shaped particle retention spectra with a minimum prey size of approximately 4 m equivalent spherical diameter, and we found that an ontogenetic increase in maximum prey size add to a reduction in intra-specific food competition in the various larval...

  19. Water Accumulation and Behavior of Surfactant Associated with Moisture Permeation in Bituminous Pavement on Concrete Deck Bridge

    OpenAIRE

    Sasaki, Iwao; Moriyoshi, Akihiro; Tsunekawa, Masami

    2006-01-01

    Water-related damage is one of the major problems for the durability of the bituminous pavement and concrete slabs of concrete deck bridges. In particular, damage can be drastically accelerated by the intervention of water and some chemicals such as surfactants and salts. Therefore, the mass transfer mechanism of water and the mechanism of chemical absorption in pavement materials are important to study. The authors previously pointed out that water storage in bituminous pavement layers is ca...

  20. BEHAVIOR OF SURFACTANT MIXTURE AT SOLID/LIQUID AND OIL/LIQUID INTERFACE IN CHEMICAL FLOODING SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Prof. P. Somasundaran

    2002-03-01

    The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Preliminary ultra-filtration tests suggest that two kinds of micelles may exist in binary surfactant mixtures at different concentrations. Due to the important role played in interfacial processes by micelles as determined by their structures, focus of the current work is on the delineation of the relationship between such aggregate structures and chemical compositions of the surfactants. A novel analytical centrifuge application is explored to generate information on structures of different surfactants aggregates. In this report, optical systems, typical output of the analytical ultracentrifuge results and four basic experiments are discussed. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. The partial specific volume was calculated to be 0.920. Four softwares: Optima{trademark} XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity experimental data. The sedimentation coefficient and aggregation number of NP-10 micelles obtained using the first three softwares at 25 C are 209, 127, and 111, respectively. The last one is closest to the result from Light Scattering. The reason for the differences in numbers obtained using the three softwares is discussed. Based on these tests, Svedberg and SEDFIT analysis are chosen for further studies. This approach using the analytical ultracentrifugation offers an unprecedented opportunity now to obtain important information on mixed micelles and their role in interfacial processes.

  1. How does dialectical behavior therapy facilitate treatment retention among individuals with comorbid borderline personality disorder and substance use disorders?

    Science.gov (United States)

    Bornovalova, Marina A; Daughters, Stacey B

    2007-12-01

    For individuals presenting with comorbid borderline personality disorder (BPD) and substance use disorders (SUD), rates of treatment dropout from combined mental health and substance abuse treatment centers approach 80%, rendering dropout the rule rather than the exception. Several studies indicate that utilizing a more comprehensive treatment such as Dialectical Behavior Therapy (DBT) may be useful for client retention; however, given the scope and effort required to conduct this treatment, it may be more practical to determine which specific components within DBT are useful in retaining clients in substance use treatment. Thus, the purpose of the current paper is first to determine what exact deficits underlie treatment dropout among the BPD-SUD comorbidity. Second, we review and evaluate effectiveness of DBT retention-enhancing strategies by assembling work from other samples and literatures that also tests retention-enhancing strategies discussed in DBT. As a last step, the paper will conclude with a discussion on methodological limitations and potential future directions in this line of research.

  2. Assessment of the percutaneous penetration of indomethacin from soybean oil microemulsion: effects of the HLB value of mixed surfactants.

    Science.gov (United States)

    Chen, Liangmei; Tan, Fengping; Wang, Jinfeng; Liu, Feng

    2012-01-01

    The objective of this study was to evaluate the influence of the ratios or the hydrophile-lipophile balance (HLB) values of Cremophor EL and Span 80 on the phase behavior of the O/W microemulsions and the percutaneous absorption and penetration of indomethacin microemulsions. The existence of microemulsion regions is investigated in quaternary systems composed of soybean oil/Cremophor EL and Span 80 (mixed surfactants)/diethylene glycol monoethyl ether (cosurfactant)/water by constructing pseudo-ternary phase diagrams at various Cremophor EL/Span 80 ratios. In addition, five microemulsion formulations with various mixed surfactants HLB values were evaluated by in vitro penetration experiments using mouse skin and Franz diffusion cells. The flux and amount of indomethacin penetration from 5 microemulsion formulations were significantly different from the control, and the enhance ratios ranged from 2.38 to 4.68 and 2.11 to 4.23, respectively. The HLB value of mixed surfactants in the formulations was a principal factor in determining the percutaneous penetration of the drug. The flux and amount of drug penetration increased gradually with increasing content of the lipophilic surfactant Span 80 and skin retention was highest for mixed surfactants with a HLB value of 7.6. Therefore, it is suggested that the presence of mixed surfactants was beneficial in the formation of O/W microemulsions and enhanced percutaneous penetration of indomethacin.

  3. Effect of hydraulic retention time on hydrodynamic behavior of anaerobic-aerobic fixed bed reactor treating cattle slaughterhouse effluent

    Directory of Open Access Journals (Sweden)

    Daiane Cristina de Freitas

    2017-09-01

    Full Text Available The study of the hydrodynamic behavior in reactors provides characteristics of the flow regime and its anomalies that can reduce biological processes efficiency due to the decrease of the useful volume and the hydraulic retention time required for the performance of microbial activity. In this study, the hydrodynamic behavior of an anaerobic-aerobic fixed bed reactor, operated with HRT (hydraulic retention time of 24, 18 and 12 hours, was evaluated in the treatment of raw cattle slaughterhouse wastewater. Polyurethane foam and expanded clay were used as support media for biomass immobilization. Experimental data of pulse type stimulus-response assays were performed with eosin Y and bromophenol blue, and adjusted to the single-parameter theoretical models of dispersion and N-continuous stirred tank reactors in series (N-CSTR. N-CSTR model presented the best adjustment for the HRT and tracers evaluated. RDT (residence time distribution curves obtained with N-CSTR model in the assays with bromophenol blue resulted in better adjustment compared to the eosin Y. The predominant flow regime in AAFBR (anaerobic aerobic fixed bed reactor is the N-CSTR in series, as well as the existence of preferential paths and hydraulic short-circuiting.

  4. Adsorption of anionic surfactants in limestone medium during oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Canbolat, Serhat; Bagci, Suat [Middle East Technical Univ., Dept. of Petroleum and Natural Gas Engineering, Ankara (Turkey)

    2004-07-15

    Foam-forming surfactant performance was evaluated by several experimental methods (interfacial tension, foam stability, corefloods) using commercial surfactants. There is considerable interest in the use of foam-forming surfactants for mobility control in water flood. To provide effective mobility control, the injected surfactant must propagate from the injection well toward the production well. One of the important parameters affecting propagation of foam-forming surfactant through the reservoir is the retention of surfactant due to its adsorption on reservoir rock. The determination of the adsorption of foam-forming surfactants in limestone reservoirs is important for the residual oil recovery efficiency. Adsorption measurements, recovery efficiencies, and surfactant and alkaline flooding experiments carried out with the representative of the selected surfactants alkaline solutions, linear alkyl benzene sulphonic acid (LABSA), sodium lauryl ether sulfate (SLES), and NaOH in a limestone medium. These surfactants were selected with respect to their foaming ability. Calibration curves formed by pH measurements were used to determine the correct adsorption amount of the used surfactants and recovery efficiency of these surfactants compared with base waterflooding. The results showed that LABSA adsorbed more than SLES in limestone reservoirs. The recovery efficiency of SLES was higher than the recovery efficiency of LABSA, and they decreased the recovery efficiency with respect to only the water injection case. (Author)

  5. Optimization of Surfactant Mixtures and Their Interfacial Behavior for Advanced Oil Recovery, Annual Report, September 30, 1999-September 30, 2000

    Energy Technology Data Exchange (ETDEWEB)

    Somasundaran, Prof. P.

    2001-04-04

    The goal of this report is to develop improved extraction processes to mobilize and produce the oil left untapped using conventional techniques. Current chemical schemes for recovering the residual oil have been in general less than satisfactory. High cost of the processes as well as significant loss of chemicals by adsorption on reservoir materials and precipitation has limited the utility of chemical-flooding operations. There is a need to develop cost-effective, improved reagent schemes to increase recovery from domestic oil reservoirs. The goal of the report was to develop and evaluate novel mixtures of surfactants for improved oil recovery.

  6. Colloid and surfactant

    International Nuclear Information System (INIS)

    Kuk, Yun Hwan; Lee, Jeong Jung; Cho, Sun Chae; Ryeo, Su Dong

    1995-08-01

    This book consists of two parts about colloid and surfactant. The first parts has explanations colloid and surface science, which deal with creation and properties of colloidal particles, surfactant and micelle colloid, property of surfactant, membranes, absorption of surface science, electrokinetic phenomenon, emulsion, foam and rheology. The second part mentions surfactant on anionic surfactant with five types, amphoteric surface active agent, non-ionic surface active agent and use of surfactant.

  7. Enhanced Oil Recovery with Surfactant Flooding

    DEFF Research Database (Denmark)

    Sandersen, Sara Bülow

    Enhanced oil recovery (EOR) is being increasingly applied in the oil industry and several different technologies have emerged during, the last decades in order to optimize oil recovery after conventional recovery methods have been applied. Surfactant flooding is an EOR technique in which the phase...... behavior inside the reservoir can be manipulated by the injection of surfactants and co-surfactants, creating advantageous conditions in order to mobilize trapped oil. Correctly designed surfactant systems together with the crude oil can create microemulsions at the interface between crude oil and water......, 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...

  8. Adsorption behavior of direct red 80 and congo red onto activated carbon/surfactant: Process optimization, kinetics and equilibrium

    Science.gov (United States)

    Cheng, Zhengjun; Zhang, Lei; Guo, Xiao; Jiang, Xiaohui; Li, Tian

    2015-02-01

    Adsorptions of congo red and direct red 80 onto activated carbon/surfactant from aqueous solution were optimized. The Box-Behnken design (BBD) has been employed to analyze the effects of concentration of surfactant, temperature, pH, and initial concentration of the dye in the adsorption capacity. Their corresponding experimental data could be evaluated excellently by second order polynomial regression models and the two models were also examined based on the analysis of variance and t test statistics, respectively. The optimum conditions were obtained as follows: Cs = 34.10 μM, T = 50 °C, pH = 3.5, and CCR = 160 mg/L for the congo red system, and Cs = 34.10 μM, T = 50 °C, pH = 6.1, and CDR80 = 110 mg/L for the direct red 80 system. And in these conditions, the measured experimental maximum adsorption capacities for the congo red and direct red 80 removals were 769.48 mg/g and 519.90 mg/g, which were consistent with their corresponding predicted values, with small relative errors of -2.81% and -0.67%, respectively. The adsorption equilibrium and kinetics for the two dye adsorptions onto AC/DDAC were also investigated. The experimental data were fitted by four isotherm models, and Langmuir model presented the best fit. The kinetic studies indicated that the kinetic data followed the pseudo-second-order model.

  9. Efficacy of Cognitive Behavioral Therapy on Opiate Use and Retention in Methadone Maintenance Treatment in China: A Randomised Trial.

    Directory of Open Access Journals (Sweden)

    Shujun Pan

    Full Text Available Methadone maintenance treatment (MMT is widely available in China; but, high rates of illicit opiate use and dropout are problematic. The aim of this study was to test whether cognitive behavioral therapy (CBT in conjunction with MMT can improve treatment retention and reduce opiate use.A total of 240 opiate-dependent patients in community-based MMT clinics were randomly assigned to either weekly CBT plus standard MMT (CBT group, n=120 or standard MMT (control group, n=120 for 26 weeks. The primary outcomes were treatment retention and opiate-negative urine test results at 12 weeks and 26 weeks. The secondary outcomes were composite scores on the Addiction Severity Index (ASI and total scores on the Perceived Stress Scale (PSS at 12 weeks and 26 weeks.Compared to the control group in standard MMT, the CBT group had higher proportion of opiate-negative urine tests at both 12 weeks (59% vs. 69%, p<0.05 and 26 weeks (63% vs. 73%, p<0.05; however, the retention rates at 12 weeks (73.3% vs. 74.2%, p=0.88 and 26 weeks were not different (55.8% vs. 64.2%, p=0.19 between the two groups. At both 12 and 26 weeks, all of the ASI component scores and PSS total scores in the CBT group and control group decreased from baseline; but the CBT group exhibited more decreases in ASI employment scores at week 26 and more decrease in the PSS total score at week 12 and week 26.CBT counselling is effective in reducing opiate use and improving employment function and in decreasing stress level for opiate-dependent patients in MMT in China.ClinicalTrials.gov NCT01144390.

  10. Transport behaviors of anionic azo dyes at interface between surfactant-modified flax shives and aqueous solution: Synchrotron infrared and adsorption studies

    International Nuclear Information System (INIS)

    Wang, Wenxia; Huang, Guohe; An, Chunjiang; Xin, Xiaying; Zhang, Yan; Liu, Xia

    2017-01-01

    Highlights: • Surfactant modified flax shives for removing anionic azo dyes. • The equilibrium and kinetic studies for the adsorption of anionic azo dyes. • The migration patterns of dye pollutants at flax shive-water interface. • New insights from synchrotron infrared-assisted characterization. • Potential as biomass adsorbent for the removal of dyes from wastewater. - Abstract: From the viewpoint of sustainability, biomass adsorbent has a high potential in pollution control and there is an emerging interest to investigate the behaviors of pollutants at the interface between biomass adsorbent and solution. This study investigated the performance of cetyltrimethylammonium bromide surfactant-modified flax shives (MFS) for removal of anionic azo dyes from aqueous solution. The equilibrium and kinetic analysis for the adsorption of Acid Orange 7 (AO-7), Acid Red 18 (AR-18) and Acid Black 1 (AB-1) on MFS were conducted. The surface of MFS was characterized by synchrotron infrared and SEM analysis. The absorbed amount of three anionic azo dyes varied with the change of adsorbent dosage, pH and ionic strength. The adsorption isotherm data well fit to the Langmuir model. The adsorption process followed the pseudo-second-order kinetics and the liquid film diffusion models. Thermodynamic studies indicated that the adsorption of three anionic azo dyes was spontaneous. The adsorption of AR-18 and AB-1 onto MFS was endothermic while the adsorption of AO-7 was exothermic. The results can help better understand the behaviors of organic pollutants at biomass adsorbent-water interface. They also present the potential of using MFS as a suitable adsorbent for the removal of anionic azo dyes from wastewater.

  11. Transport behaviors of anionic azo dyes at interface between surfactant-modified flax shives and aqueous solution: Synchrotron infrared and adsorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenxia [MOE Key Laboratory of Resources and Environmental Systems Optimization, Institute for Energy, Environment and Sustainability Research, UR-NCEPU, North China Electric Power University, Beijing, 102206 (China); Huang, Guohe, E-mail: huang@iseis.org [MOE Key Laboratory of Resources and Environmental Systems Optimization, Institute for Energy, Environment and Sustainability Research, UR-NCEPU, North China Electric Power University, Beijing, 102206 (China); An, Chunjiang; Xin, Xiaying [Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, S4S 0A2 (Canada); Zhang, Yan [MOE Key Laboratory of Resources and Environmental Systems Optimization, Institute for Energy, Environment and Sustainability Research, UR-NCEPU, North China Electric Power University, Beijing, 102206 (China); Liu, Xia [Canadian Light Source, Saskatoon, S7N 2V3 (Canada)

    2017-05-31

    Highlights: • Surfactant modified flax shives for removing anionic azo dyes. • The equilibrium and kinetic studies for the adsorption of anionic azo dyes. • The migration patterns of dye pollutants at flax shive-water interface. • New insights from synchrotron infrared-assisted characterization. • Potential as biomass adsorbent for the removal of dyes from wastewater. - Abstract: From the viewpoint of sustainability, biomass adsorbent has a high potential in pollution control and there is an emerging interest to investigate the behaviors of pollutants at the interface between biomass adsorbent and solution. This study investigated the performance of cetyltrimethylammonium bromide surfactant-modified flax shives (MFS) for removal of anionic azo dyes from aqueous solution. The equilibrium and kinetic analysis for the adsorption of Acid Orange 7 (AO-7), Acid Red 18 (AR-18) and Acid Black 1 (AB-1) on MFS were conducted. The surface of MFS was characterized by synchrotron infrared and SEM analysis. The absorbed amount of three anionic azo dyes varied with the change of adsorbent dosage, pH and ionic strength. The adsorption isotherm data well fit to the Langmuir model. The adsorption process followed the pseudo-second-order kinetics and the liquid film diffusion models. Thermodynamic studies indicated that the adsorption of three anionic azo dyes was spontaneous. The adsorption of AR-18 and AB-1 onto MFS was endothermic while the adsorption of AO-7 was exothermic. The results can help better understand the behaviors of organic pollutants at biomass adsorbent-water interface. They also present the potential of using MFS as a suitable adsorbent for the removal of anionic azo dyes from wastewater.

  12. TRENDS [Transport and Retention of Nuclides in Dominant Sequences]: A code for modeling iodine behavior in containment during severe accidents

    International Nuclear Information System (INIS)

    Weber, C.F.; Beahm, E.C.; Kress, T.S.; Daish, S.R.; Shockley, W.E.

    1989-01-01

    The ultimate aim of a description of iodine behavior in severe LWR accidents is a time-dependent accounting of iodine species released into containment and to the environment. Factors involved in the behavior of iodine can be conveniently divided into four general categories: (1) initial release into containment, (2) interaction of iodine species in containment not directly involving water pools, (3) interaction of iodine species in, or with, water pools, and (4) interaction with special systems such as ice condensers or gas treatment systems. To fill the large gaps in knowledge and to provide a means for assaying the iodine source term, this program has proceeded along two paths: (1) Experimental studies of the chemical behavior of iodine under containment conditions. (2) Development of TRENDS (Transport and Retention of Nuclides in Dominant Sequences), a computer code for modeling the behavior of iodine in containment and its release from containment. The main body of this report consists of a description of TRENDS. These two parts to the program are complementary in that models within TRENDS use data that were produced in the experimental program; therefore, these models are supported by experimental evidence that was obtained under conditions expected in severe accidents. 7 refs., 1 fig., 2 tabs

  13. Synthesis, micellization behavior, antimicrobial and intercalative DNA binding of some novel surfactant copper(II) complexes containing modified phenanthroline ligands.

    Science.gov (United States)

    Nagaraj, Karuppiah; Ambika, Subramanian; Rajasri, Shanmugasundaram; Sakthinathan, Subramanian; Arunachalam, Sankaralingam

    2014-10-01

    The novel surfactant copper(II) complexes, [Cu(ip)2DA](ClO4)21, [Cu(dpqc)2DA](ClO4)22, [Cu(dppn)2DA](ClO4)23, where ip=imidazo[4,5-f][1,10]phenanthroline, dpqc=dipyrido[3,2-a:2',4'-c](6,7,8,9-tetrahydro)phenazine, dppn=benzo[1]dipyrido[3,2-a':2',3'-c]phenazine and DA-dodecylamine, were synthesized and characterized by physico-chemical and spectroscopic methods. In these complexes 1-3, the geometry of copper metal ions was described as square pyramidal. The critical micelle concentration (CMC) value of these surfactant copper(II) complexes in aqueous solution was found out from conductance measurements. Specific conductivity data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGm°, ΔHm° and ΔSm°). The binding interaction of these complexes with DNA (calf thymus DNA) in Tris buffer was studied by physico-chemical techniques. In the presence of the DNA UV-vis spectrum of complexes showed red shift of the absorption band along with significant hypochromicity indicating intercalation of our complexes with nucleic acids. Competitive binding study with ethidium bromide (EB) shows that the complexes exhibit the ability to displace the nucleic acid-bound EB indicating that the complexes bind to nucleic acids in strong competition with EB for the intercalative binding site. Observed changes in the circular dichoric spectra of DNA in the presence of surfactant complexes support the strong binding of complexes with DNA. CV results also confirm this mode of binding. Some significant thermodynamic parameters of the binding of the titled complexes to DNA have also been determined. The results reveal that the extent of DNA binding of 3 was greater than that of 1 and 2. The antibacterial and antifungal screening tests of these complexes have shown good results compared to its precursor chloride complexes. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. The effect of dilution on the gas-retention behavior of Tank 241-SY-101 waste

    International Nuclear Information System (INIS)

    Bredt, P.R.; Tingey, S.M.; Shade, E.H.

    1995-09-01

    The effect of dilution on gas retention in waste from Tank 241-SY-101 was investigated. A composite sample was prepared from material collected during the Window ''C'' and Window ''E'' sampling events. The composite contained material from both the convective and nonconvective layer in the proportions existing in the tank. Operation of the mixer pump in Tank 241-SY-101 has homogenized the tank material, and dilution of the current waste would require additional mixing; therefore, no attempt was made to use unhomogenized tank waste to prepare the composite. The composite was diluted with 2 M NaOH at ratios of 0.5:1, 0.75: 1, 1:1, and 3:1 per volume (2 M NaOH:tank waste)

  15. Adsorption behavior of direct red 80 and congo red onto activated carbon/surfactant: process optimization, kinetics and equilibrium.

    Science.gov (United States)

    Cheng, Zhengjun; Zhang, Lei; Guo, Xiao; Jiang, Xiaohui; Li, Tian

    2015-02-25

    Adsorptions of congo red and direct red 80 onto activated carbon/surfactant from aqueous solution were optimized. The Box-Behnken design (BBD) has been employed to analyze the effects of concentration of surfactant, temperature, pH, and initial concentration of the dye in the adsorption capacity. Their corresponding experimental data could be evaluated excellently by second order polynomial regression models and the two models were also examined based on the analysis of variance and t test statistics, respectively. The optimum conditions were obtained as follows: Cs=34.10 μM, T=50°C, pH=3.5, and CCR=160 mg/L for the congo red system, and Cs=34.10 μM, T=50°C, pH=6.1, and CDR80=110 mg/L for the direct red 80 system. And in these conditions, the measured experimental maximum adsorption capacities for the congo red and direct red 80 removals were 769.48 mg/g and 519.90 mg/g, which were consistent with their corresponding predicted values, with small relative errors of -2.81% and -0.67%, respectively. The adsorption equilibrium and kinetics for the two dye adsorptions onto AC/DDAC were also investigated. The experimental data were fitted by four isotherm models, and Langmuir model presented the best fit. The kinetic studies indicated that the kinetic data followed the pseudo-second-order model. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. [Exogenous surfactant therapy: new synthetic surfactants].

    Science.gov (United States)

    Lacaze-Masmonteil, Th

    2008-06-01

    There are numerous pulmonary conditions in which qualitative or quantitative anomalies of the surfactant system have been demonstrated. In premature newborns with immature lungs, a functional deficit in surfactant is the main physiopathologic mechanism of the neonatal respiratory distress syndrome (RDS). Since the landmark pilot study of Fujiwara, published more than 20 years ago, the efficacy of exogenous surfactant for the treatment of neonatal RDS has been established by numerous controlled studies and meta-analyses. Enlightened by a growing insight into both the structure and function of the different surfactant components, a new generation of synthetic surfactants has been developed. Various complementary approaches have confirmed the fundamental role of the two hydrophobic proteins, SP-B and SP-C, in the surfactant system, thus opening the way to the design of analogues, either by chemical synthesis or expression in a prokaryotic system. An example of these peptide-containing synthetic surfactant preparations, lucinactant (Surfaxin), has been recently tested in comparison to a synthetic surfactant that does not contain protein as well as to animal derived surfactant preparations. Major clinical outcomes between lucinactant and animal-derived surfactant preparations were fund similar in two randomized controlled trials, opening the way to a new generation of synthetic surfactants in the near future.

  17. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. 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%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil-wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate-wet for many surfactants and water-wet for one surfactant. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting core adsorption, phase behavior, wettability and mobilization studies.

  18. Protective effect of the calcium antagonist nimodipine on discrimination learning deficits and impaired retention behavior caused by prenatal nitrite exposure in rats

    NARCIS (Netherlands)

    Nyakas, Csaba; Markel, Éva; Bohus, Béla; Schuurman, Teun; Luiten, Paulus

    1990-01-01

    Discrimination learning behavior and retention of a passive avoidance response were studied in male adult offspring of gestating rats exposed to drinking water containing 2 g/l sodium nitrite, throughout the second half of pregnancy. Both in an auditory and visual discrimination learning paradigm

  19. Transport behaviors of anionic azo dyes at interface between surfactant-modified flax shives and aqueous solution: Synchrotron infrared and adsorption studies

    Science.gov (United States)

    Wang, Wenxia; Huang, Guohe; An, Chunjiang; Xin, Xiaying; Zhang, Yan; Liu, Xia

    2017-05-01

    From the viewpoint of sustainability, biomass adsorbent has a high potential in pollution control and there is an emerging interest to investigate the behaviors of pollutants at the interface between biomass adsorbent and solution. This study investigated the performance of cetyltrimethylammonium bromide surfactant-modified flax shives (MFS) for removal of anionic azo dyes from aqueous solution. The equilibrium and kinetic analysis for the adsorption of Acid Orange 7 (AO-7), Acid Red 18 (AR-18) and Acid Black 1 (AB-1) on MFS were conducted. The surface of MFS was characterized by synchrotron infrared and SEM analysis. The absorbed amount of three anionic azo dyes varied with the change of adsorbent dosage, pH and ionic strength. The adsorption isotherm data well fit to the Langmuir model. The adsorption process followed the pseudo-second-order kinetics and the liquid film diffusion models. Thermodynamic studies indicated that the adsorption of three anionic azo dyes was spontaneous. The adsorption of AR-18 and AB-1 onto MFS was endothermic while the adsorption of AO-7 was exothermic. The results can help better understand the behaviors of organic pollutants at biomass adsorbent-water interface. They also present the potential of using MFS as a suitable adsorbent for the removal of anionic azo dyes from wastewater.

  20. Initial transport and retention behaviors of ZnO nanoparticles in quartz sand porous media coated with Escherichia coli biofilm

    International Nuclear Information System (INIS)

    Jiang, Xujia; Wang, Xueting; Tong, Meiping; Kim, Hyunjung

    2013-01-01

    The significance of biofilm on the transport and deposition behaviors of ZnO nanoparticles were examined under a series of environmentally relevant ionic strength at two fluid velocities of 4 m-d −1 and 8 m-d −1 . Biofilm enhanced nanoparticles retention in porous media under all examined conditions. The greater deposition was also observed in extracellular polymeric substances (EPS) coated surfaces by employment of quartz microbalance with dissipation (QCM-D) system. Derjaguin–Landau–Verwey–Overbeek (DLVO) failed to interpret more ZnO nanoparticles deposition on biofilm (EPS) coated silica surfaces. Chemical interaction and physical morphology of biofilm contributed to this greater deposition (retention). Biofilm affected the spacial distribution of retained ZnO nanoparticles as well. Relatively steeper slope of retained profiles were observed in the presence of biofilm, corresponding to the greater deviation from colloid filtration theory (CFT). Pore space constriction via biofilm induced more nanoparticle trapped in the column inlet, leading to greater deviations (σln k f ) from the CFT. Highlights: ► Biofilm reduced the mobility of ZnO nanoparticles in column. ► DLVO and non-DLVO interactions contributed the more nanoparticles deposition. ► Biofilm also affected the spacial distribution of ZnO nanoparticles in column. ► Greater deviation from classic filtration theory was observed with biofilm. ► Physical structure of biofilm induced greater deviation from log-linear prediction. -- Biofilm enhanced ZnO nanoparticle deposition and altered spacial distribution in porous media

  1. Comparison of the performance of non-ionic and anionic surfactants as mobile phase additives in the RPLC analysis of basic drugs.

    Science.gov (United States)

    Ruiz-Ángel, María J; García-Álvarez-Coque, María C

    2011-03-01

    Surfactants added to the mobile phases in reversed-phase liquid chromatography (RPLC) give rise to a modified stationary phase, due to the adsorption of surfactant monomers. Depending on the surfactant nature (ionic or non-ionic), the coated stationary phase can exhibit a positive net charge, or just change its polarity remaining neutral. Also, micelles in the mobile phase introduce new sites for solute interaction. This affects the chromatographic behavior, especially in the case of basic compounds. Two surfactants of different nature, the non-ionic Brij-35 and the anionic sodium dodecyl sulfate (SDS) added to water or aqueous-organic mixtures, are here compared in the separation of basic compounds (β-blockers and tricyclic antidepressants). The reversible/irreversible adsorption of the monomers of both surfactants on the stationary phase was examined. The changes in the nature of the chromatographic system using different columns and chromatographic conditions were followed based on the changes in retention and peak shape. The study revealed that Brij-35 is suitable for analyzing basic compounds of intermediate polarity, using "green chemistry", since the addition of an organic solvent is not needed and Brij-35 is a biodegradable surfactant. In contrast, RPLC with hydro-organic mixtures or mobile phases containing SDS required high concentrations of organic solvents. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effects of surfactants on graphene oxide nanoparticles transport in saturated porous media.

    Science.gov (United States)

    Fan, Wei; Jiang, Xuehui; Lu, Ying; Huo, Mingxin; Lin, Shanshan; Geng, Zhi

    2015-09-01

    Transport behaviors of graphene oxide nanoparticles (GONPs) in saturated porous media were examined as a function of the presence and concentration of anionic surfactant (SDBS) and non-ionic surfactant (Triton X-100) under different ionic strength (IS). The results showed that the GONPs were retained obviously in the sand columns at both IS of 50 and 200mmol/L, and they were more mobile at lower IS. The presence and concentration of surfactants could enhance the GONP transport, particularly as observed at higher IS. It was interesting to see that the GONP transport was surfactant type dependent, and SDBS was more effective to facilitate GONP transport than Triton X-100 in our experimental conditions. The advection-dispersion-retention numerical modeling followed this trend and depicted the difference quantitatively. Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction calculations also were performed to interpret these effects, indicating that secondary minimum deposition was critical in this study. Copyright © 2015. Published by Elsevier B.V.

  3. Swimming behavior and prey retention of the polychaete larvae Polydora ciliata (Johnston)

    DEFF Research Database (Denmark)

    Hansen, B.W.; Jakobsen, Hans Henrik; Andersen, Anders Peter

    2010-01-01

    in specific feeding rates and the observed increase in the difference between upward and downward swimming speeds with larval size. We estimated a critical larval length above which the buoyancy-corrected weight of the larva exceeds the propulsion force generated by the ciliary swimming apparatus and thus......The behavior of the ubiquitous estuarine planktotrophic spionid polychaete larvae Polydora ciliata was studied. We describe ontogenetic changes in morphology, swimming speed and feeding rates and have developed a simple swimming model using low Reynolds number hydrodynamics. In the model we assumed...... that the ciliary swimming apparatus is primarily composed of the prototroch and secondarily by the telotroch. The model predicted swimming speeds and feeding rates that corresponded well with the measured speeds and rates. Applying empirical data to the model, we were able to explain the profound decrease...

  4. Gemini (dimeric) Surfactants

    Indian Academy of Sciences (India)

    Gemini, surfactants, micelle. Figure 1. Schematic repre- sentation of the gemini sur- factant structure. B S Sekhon. A gemini surfactant (GS) consists of two conventional surfactant molecules chemically bonded together by a spacer. The two terminal hydrocarbon tails can be short or long; the two polar head groups can be ...

  5. Status of surfactants as penetration enhancers in transdermal drug delivery

    Directory of Open Access Journals (Sweden)

    Iti Som

    2012-01-01

    Full Text Available Surfactants are found in many existing therapeutic, cosmetic, and agro-chemical preparations. In recent years, surfactants have been employed to enhance the permeation rates of several drugs via transdermal route. The application of transdermal route to a wider range of drugs is limited due to significant barrier to penetration across the skin which is associated with the outermost stratum corneum layer. Surfactants have effects on the permeability characteristics of several biological membranes including skin. They have the potential to solubilize lipids within the stratum corneum. The penetration of the surfactant molecule into the lipid lamellae of the stratum corneum is strongly dependent on the partitioning behavior and solubility of surfactant. Surfactants ranging from hydrophobic agents such as oleic acid to hydrophilic sodium lauryl sulfate have been tested as permeation enhancer to improve drug delivery. This article reviews the status of surfactants as permeation enhancer in transdermal drug delivery of various drugs.

  6. Application of nanofiltration membranes for removal of surfactants from water solutions

    Directory of Open Access Journals (Sweden)

    Kowalska Izabela

    2017-01-01

    Full Text Available The objective of the study was to compare effectiveness of nanofiltration (NF process for treatment aqueous solutions containing various types of surfactants (anionic, cationic and non-ionic. The experiments were conducted with the use of Microdyn-Nadir® nanofiltration membranes (NP010 and NP030. The effect of surfactant type, its concentration and membrane cut-off on the process parameters (retention coefficient and permeate flux was assessed. The experiments showed that separation of anionic and cationic surfactants depended on their concentration in the feed solutions. The retention coefficient of anionic surfactant ranged from 54 to 81% (NP010 and from 64 to 80% (NP030, while rejection of cationic surfactant varied from 48 to 85% (NP010 and from 51 to 88% (NP030. The values of retention coefficient of non-ionic surfactant were in the range of 69-77% and 79-88% for NP010 and NP030, respectively; and to a much lesser extent were depended on its concentration in the feed solutions in comparison with anionic and cationic compounds. Membrane characterized by smaller value of cut-off (NP030 allowed to obtain higher retention coefficients of surfactants. The membrane permeability deterioration was observed with the increase of surfactants concentration in the treated solutions. In all experiments, a sharp decline of the permeate flux was noticed for concentration below the CMC values.

  7. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. 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%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate wettability. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  8. A Study of the Effect of Surfactants on the Aggregation Behavior of Crude Oil Aqueous Dispersions through Steady-State Fluorescence Spectrometry.

    Science.gov (United States)

    Vallejo-Cardona, Alba A; Cerón-Camacho, Ricardo; Karamath, James R; Martínez-Palou, Rafael; Aburto, Jorge

    2017-07-01

    Unconventional crude oil as heavy, extra heavy, bitumen, tight, and shale oils will meet 10% of worldwide needs for 2035, perhaps earlier. Petroleum companies will face problems concerning crude oil extraction, production, transport, and refining, and some of these are addressed by the use of surfactants and other chemicals. For example, water-in-crude oil emulsions are frequently found during the production of mature wells where enhanced recovery techniques have been deployed. Nevertheless, the selection of adequate surfactant, dosage, type of water (sea, tap or oilfield), kind of crude oil (light, heavy, extra heavy, tight, shale, bitumen) affect the effectivity of treatment and usual bottle tests give limited information. We developed a fluorescence technique to study the effect of surfactants on medium, heavy, and extra heavy crude oil employing the natural fluorophore molecules from petroleum. We first carried out the characterization of commercial and synthetic surfactants, then dispersions of petroleum in water were studied by steady-state fluorometry and the size of petroleum aggregates were measured. The aggregation of petroleum incremented from medium to extra heavy crude oil and we discussed the effect of different surfactants on such aggregation.

  9. Effects of silica-based nanostructures with raspberry-like morphology and surfactant on the interfacial behavior of light, medium, and heavy crude oils at oil-aqueous interfaces

    Science.gov (United States)

    Bai, Lingyun; Li, Chunyan; Korte, Caroline; Huibers, Britta M. J.; Pales, Ashley R.; Liang, Wei-zhen; Ladner, David; Daigle, Hugh; Darnault, Christophe J. G.

    2017-11-01

    Any efficient exploitation of new petroleum reservoirs necessitates developing methods to mobilize the crude oils from such reservoirs. Here silicon dioxide nanoparticles (SiO2 NPs) were used to improve the efficiency of the chemical-enhanced oil recovery process that uses surfactant flooding. Specifically, SiO2 NPs (i.e., 0, 0.001, 0.005, 0.01, 0.05, and 0.1 wt%) and Tween®20, a nonionic surfactant, at 0, 0.5, and 2 critical micelle concentration (CMC) were varied to determine their effect on the stability of nanofluids and the interfacial tension (IFT) at the oil-aqueous interface for 5 wt% brine-surfactant-SiO2 nanofluid-oil systems for West Texas Intermediate light crude oil, Prudhoe Bay medium crude oil, and Lloydminster heavy crude oil. Our study demonstrates that SiO2 NPs may either decrease, increase the IFT of the brine-surfactant-oil systems, or exhibit no effects at all. For the brine-surfactant-oil systems, the constituents of the oil and aqueous substances affected the IFT behavior, with the nanoparticles causing a contrast in IFT trends according to the type of crude oil. For the light oil system (0.5 and 2 CMC Tween®20), the IFT increased as a function of SiO2 NP concentration, while a threshold concentration of SiO2 NPs was observed for the medium (0.5 and 2 CMC Tween®20) and heavy (2 CMC Tween®20) oil systems in terms of IFT trends. Concentrations below the SiO2 NP threshold concentration resulted in a decrease in IFT, and concentrations above this threshold resulted in an increase in IFT. The IFT decreased until the NP concentration reached a threshold concentration where synergetic effects between nonionic surfactants and SiO2 NPs are the opposite and result in antagonistic effects. Adsorption of both SiO2 NPs and surfactants at an interface caused a synergistic effect and an increased reduction in IFT. The effectiveness of the brine-surfactant-SiO2 nanofluids in decreasing the IFT between the oil-aqueous phase for the three tested crude oils

  10. 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

  11. Comparison of aggregation behaviors between ionic liquid-type imidazolium gemini surfactant [C12-4-C12im]Br2 and its monomer [C12mim]Br on silicon wafer.

    Science.gov (United States)

    Ao, Mingqi; Xu, Guiying; Pang, Jinyu; Zhao, Taotao

    2009-09-01

    The aggregation of ionic liquid-type imidazolium gemini surfactant [C(12)-4-C(12)im]Br(2) on silicon wafer, which is compared with its monomer [C(12)mim]Br, have been studied. AFM morphology images and contact angle measurements suggest that the aggregations of [C(12)-4-C(12)im]Br(2) and [C(12)mim]Br on silicon wafer follow different mechanisms. Below the critical surface aggregation concentrations (CSAC), both surfactant molecules are adsorbed with their hydrophobic tails facing the air. But above the CSAC, [C(12)-4-C(12)im]Br(2) molecules finally form a bilayer structure with hydrophilic head groups facing the air, whereas [C(12)mim]Br molecules form a multilayer structure, and with increasing its concentration, the layer numbers increase with the hydrophobic chains and hydrophilic head groups facing the air by turns. Besides, the watery wettability of [C(12)-4-C(12)im]Br(2)-treated silica surface is lower than that of [C(12)mim]Br at the concentration of 5.0 cmc, and the infrared spectroscopy suggests that the poorer watery wettability of [C(12)-4-C(12)im]Br(2) may be relative to the less-ordered packing of methylene chains inside the aggregate. These different aggregation behaviors for the two surfactants ascribe to the different molecular structures and electrostatic interactions. This work would have certain theoretical guidance meaning on the modification of solid surface.

  12. Di-Peptide-Modified Gemini Surfactants as Gene Delivery Vectors: Exploring the Role of the Alkyl Tail in Their Physicochemical Behavior and Biological Activity.

    Science.gov (United States)

    Al-Dulaymi, Mays A; Chitanda, Jackson M; Mohammed-Saeid, Waleed; Araghi, Hessamaddin Younesi; Verrall, Ronald E; Grochulski, Pawel; Badea, Ildiko

    2016-09-01

    The aim of this work was to elucidate the structure-activity relationship of new peptide-modified gemini surfactant-based carriers. Glycyl-lysine modified gemini surfactants that differ in the length and degree of unsaturation of their alkyl tail were used to engineer DNA nano-assemblies. To probe the optimal nitrogen to phosphate (N/P) ratio in the presence of helper lipid, in vitro gene expression and cell toxicity measurements were carried out. Characterization of the nano-assemblies was accomplished by measuring the particle size and surface charge. Morphological characteristics and lipid organization were studied by small angle X-ray scattering technique. Lipid monolayers were studied using a Langmuir-Blodgett trough. The highest activity of glycyl-lysine modified gemini surfactants was observed with the 16-carbon tail compound at 2.5 N/P ratio, showing a 5- to 10-fold increase in the level of reporter protein compared to the 12 and 18:1 carbon tail compounds. This ratio is significantly lower compared to the previously studied gemini surfactants with alkyl or amino- spacers. In addition, the 16-carbon tail compound exhibited the highest cell viability (85%). This high efficiency is attributed to the lowest critical micelle concentration of the 16-tail gemini surfactant and a balanced packing of the nanoparticles by mixing a saturated and unsaturated lipid together. At the optimal N/P ratio, all nanoparticles exhibited an inverted hexagonal lipid assembly. The results show that the length and nature of the tail of the gemini surfactants play an important role in determining the transgene efficiency of the delivery system. We demonstrated here that the interplay between the headgroup and the nature of tail is specific to each series, thus in the process of rational design, the contribution of the latter should be assessed in the appropriate context.

  13. Genetics Home Reference: surfactant dysfunction

    Science.gov (United States)

    ... Email Facebook Twitter Home Health Conditions Surfactant dysfunction Surfactant dysfunction Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Surfactant dysfunction is a lung disorder that causes breathing ...

  14. Recruitment and retention of low-income minority women in a behavioral intervention to reduce smoking, depression, and intimate partner violence during pregnancy

    Directory of Open Access Journals (Sweden)

    Murray Kennan B

    2007-09-01

    Full Text Available Abstract Background Researchers have frequently encountered difficulties in the recruitment and retention of minorities resulting in their under-representation in clinical trials. This report describes the successful strategies of recruitment and retention of African Americans and Latinos in a randomized clinical trial to reduce smoking, depression and intimate partner violence during pregnancy. Socio-demographic characteristics and risk profiles of retained vs. non-retained women and lost to follow-up vs. dropped-out women are presented. In addition, subgroups of pregnant women who are less (more likely to be retained are identified. Methods Pregnant African American women and Latinas who were Washington, DC residents, aged 18 years or more, and of 28 weeks gestational age or less were recruited at six prenatal care clinics. Potentially eligible women were screened for socio-demographic eligibility and the presence of the selected behavioral and psychological risks using an Audio Computer-Assisted Self-Interview. Eligible women who consented to participate completed a baseline telephone evaluation after which they were enrolled in the study and randomly assigned to either the intervention or the usual care group. Results Of the 1,398 eligible women, 1,191 (85% agreed to participate in the study. Of the 1,191 women agreeing to participate, 1,070 completed the baseline evaluation and were enrolled in the study and randomized, for a recruitment rate of 90%. Of those enrolled, 1,044 were African American women. A total of 849 women completed the study, for a retention rate of 79%. Five percent dropped out and 12% were lost-to-follow up. Women retained in the study and those not retained were not statistically different with regard to socio-demographic characteristics and the targeted risks. Retention strategies included financial and other incentives, regular updates of contact information which was tracked and monitored by a computerized data

  15. The Effect of Voice Ambulatory Biofeedback on the Daily Performance and Retention of a Modified Vocal Motor Behavior in Participants With Normal Voices.

    Science.gov (United States)

    Van Stan, Jarrad H; Mehta, Daryush D; Hillman, Robert E

    2015-06-01

    Ambulatory biofeedback has potential to improve carryover of newly established vocal motor behaviors into daily life outside of the clinic and warrants systematic research that is lacking in the literature. This proof-of-concept study was designed to establish an empirical basis for future work in this area by formally assessing whether ambulatory biofeedback reduces daily vocal intensity (performance) and the extent to which this change remains after biofeedback removal (retention). Six participants with normal voices wore the KayPENTAX Ambulatory Phonation Monitor for 3 baseline days followed by 4 days with biofeedback provided on odd days. Compared to baseline days, participants exhibited a statistically significant decrease in mean vocal intensity (4.4 dB) and an increase in compliance (16.8 percentage points) when biofeedback was provided above a participant-specific intensity threshold. After biofeedback removal, mean vocal intensity and compliance reverted back to baseline levels. These findings suggest that although current ambulatory biofeedback approaches have potential to modify a vocal motor behavior, the modified behavior may not be retained after biofeedback removal. Future work calls for the testing of more innovative ambulatory biofeedback approaches on the basis of motor control and learning theories to improve retention of a desired vocal motor behavior.

  16. Alkyl-imidazolium glycosides: non-ionic-cationic hybrid surfactants from renewable resources.

    Science.gov (United States)

    Salman, Abbas Abdulameer; Tabandeh, Mojtaba; Heidelberg, Thorsten; Hussen, Rusnah Syahila Duali; Ali, Hapipah Mohd

    2015-08-14

    A series of surfactants combining carbohydrate and imidazolium head groups were prepared and investigated on their assembly behavior. The presence of the imidazolium group dominated the interactions of the surfactants, leading to high CMCs and large molecular surface areas, reflected in curved rather than lamellar surfactant assemblies. The carbohydrate, on the other hand, stabilized molecular assemblies slightly and reduced the surface tension of surfactant solutions considerably. A comparative emulsion study discourages the use of pure alkyl imidazolium glycosides owing to reduced assembly stabilities compared with APGs. However, the surfactants are believed to have potential as component in carbohydrate based surfactant mixtures. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Nonionic surfactant Brij35 effects on toluene biodegradation in a ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... behaviors of toluene in a composite bead biofilter were investigated. The toluene dissolved in the water phase was enhanced by the addition of surfactant into aqueous solution and the enhancing effect was more pronounced in the surfactant concentration less than critical micelle concentration. For the.

  18. Nonionic surfactant Brij35 effects on toluene biodegradation in a ...

    African Journals Online (AJOL)

    Nonionic surfactant effects on the toluene dissolved in the water phase and biodegradation kinetic behaviors of toluene in a composite bead biofilter were investigated. The toluene dissolved in the water phase was enhanced by the addition of surfactant into aqueous solution and the enhancing effect was more pronounced ...

  19. New Y-shaped surfactants from renewable resources.

    Science.gov (United States)

    Ali, Tammar Hussein; Hussen, Rusnah Syahila Duali; Heidelberg, Thorsten

    2014-11-01

    A series of sugar-based surfactants, involving a single hydrophobic chain (C12) and two side-by-side arranged head groups, was prepared form simple glucose precursors. All surfactants were highly water soluble and exhibited exclusively micellar assemblies. This behavior makes them interesting candidates for oil in water emulsifiers. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. On the rheology of mixed systems of hydrophobically modified polyacrylate microgels and surfactants: Role of the surfactant architecture.

    Science.gov (United States)

    Alves, Luís; Lindman, Björn; Klotz, Björn; Böttcher, Axel; Haake, Hans-Martin; Antunes, Filipe E

    2018-03-01

    The rheological control of suspensions is of key interest in the formulation design. A chemically cross-linked hydrophobically modified poly(acrylic acid) (HMCL-PAA), used as rheology modifier, is pH sensitive and shows swelling behavior above a critical pH due to the ionization of the acrylic acid groups. At low pH, HMCL-PAA suspensions are liquid and turbid. The binding of surfactants to HMCL-PAA, at low pH conditions, can result in significant changes on rheology and transparency of the polymeric suspensions, due to the swelling of the microgel particles. The influence of surfactants addition on the rheological properties and transparency of HMCL-PAA suspensions was determined. A systematic study was performed using different types of surfactants (ionic, non-ionic and zwitterionic). The gelation efficiency of HMCL-PAA suspensions at low pH is strongly dependent on surfactant architecture: ionic surfactants are found to be much more efficient than non-ionic or zwitterionic surfactants. Ionic surfactants lead to a liquid-to-gel transition accompanied by an increase of transparency of the suspensions. Among the ionic surfactants, anionics show stronger interactions with the polymer. Also the surfactant hydrophobicity is relevant; the more hydrophobic the surfactant, the stronger is the binding to the polymer and thus the larger the particle swelling. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Molecular simulation of surfactant-assisted protein refolding

    Science.gov (United States)

    Lu, Diannan; Liu, Zheng; Liu, Zhixia; Zhang, Minlian; Ouyang, Pingkai

    2005-04-01

    Protein refolding to its native state in vitro is a challenging problem in biotechnology, i.e., in the biomedical, pharmaceutical, and food industry. Protein aggregation and misfolding usually inhibit the recovery of proteins with their native states. These problems can be partially solved by adding a surfactant into a suitable solution environment. However, the process of this surfactant-assisted protein refolding is not well understood. In this paper, we wish to report on the first-ever simulations of surfactant-assisted protein refolding. For these studies, we defined a simple model for the protein and the surfactant and investigated how a surfactant affected the folding behavior of a two-dimensional lattice protein molecule. The model protein and model surfactant were chosen such that we could capture the important features of the folding process and the interaction between the protein and the surfactant, namely, the hydrophobic interaction. It was shown that, in the absence of surfactants, a protein in an "energy trap" conformation, i.e., a local energy minima, could not fold into the native form, which was characterized by a global energy minimum. The addition of surfactants created folding pathways via the formation of protein-surfactant complexes and thus enabled the conformations that fell into energy trap states to escape from these traps and to form the native proteins. The simulation results also showed that it was necessary to match the hydrophobicity of surfactant to the concentration of denaturant, which was added to control the folding or unfolding of a protein. The surfactants with different hydrophobicity had their own concentration range on assisting protein refolding. All of these simulations agreed well with experimental results reported elsewhere, indicating both the validity of the simulations presented here and the potential application of the simulations for the design of a surfactant on assisting protein refolding.

  2. Fundamentals of surfactant sputtering

    International Nuclear Information System (INIS)

    Hofsaess, Hans; Zhang Kun

    2009-01-01

    We introduce a new sputter technique, utilizing the steady-state coverage of a substrate surface with up to 10 16 cm -2 of foreign atoms simultaneously during sputter erosion by combined ion irradiation and atom deposition. These atoms strongly modify the substrate sputter yield on atomic to macroscopic length scales and therefore act as surfactant atoms (a blend of 'surface active agent'). Depending on the surfactant-substrate combination, the novel technique allows enhanced surface smoothing, generation of novel surface patterns, shaping of surfaces and formation of ultra-thin films. Sputter yield attenuation is demonstrated for sputtering of Si and Fe substrates and different surfactant species using 5 keV Xe ions at different incidence angles and fluences up to 10 17 cm -2 . Analytical approaches and Monte Carlo simulations are used to predict the sputtering yield attenuation as function of surfactant coverage. For sputtering of Si with Au surfactants we observe high sputter yields despite a steady-state surfactant coverage, which can be explained by strong ion-induced interdiffusion of substrate and surfactant atoms and the formation of a buried Au x Si surfactant layer in dynamic equilibrium.

  3. 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.

  4. Surfactant-Solvent Interaction Effects on the Micellization of Cationic Surfactants in a Carboxylic Acid-Based Deep Eutectic Solvent.

    Science.gov (United States)

    Sanchez-Fernandez, Adrian; Hammond, Oliver S; Jackson, Andrew J; Arnold, Thomas; Doutch, James; Edler, Karen J

    2017-12-19

    Deep eutectic solvents have been demonstrated to support amphiphile self-assembly, providing potential alternatives as structure-directing agents in the synthesis of nanostructures, and drug delivery. Here we have expanded on this recent research to investigate the self-assembly of alkyltrimethylammonium bromide surfactants in choline chloride:malonic acid deep eutectic solvent and mixtures of the solvent with water. Surface tension and small-angle neutron scattering were used to determine the behavior of the amphiphiles. Surfactants were found to remain active in the solvent, and surface tension measurements revealed changes in the behavior of the surfactants with different levels of hydration. Small-angle neutron scattering shows that in this solvent the micelle shape depends on the surfactant chain length, varying from globular micelles (aspect ratio ∼2) for short chain surfactants to elongated micelles (aspect ratio ∼14) for long chain surfactants even at low surfactant concentration. We suggest that the formation of elongated micelles can be explained through the interaction of the solvent with the surfactant headgroup, since ion-ion interactions between surfactant headgroups and solvent may modify the morphology of the micelles. The presence of water in the deep eutectic solvents promotes an increase in the charge density at the micelle interface and therefore the formation of less elongated, globular micelles.

  5. QSRR modeling for the chromatographic retention behavior of some β-lactam antibiotics using forward and firefly variable selection algorithms coupled with multiple linear regression.

    Science.gov (United States)

    Fouad, Marwa A; Tolba, Enas H; El-Shal, Manal A; El Kerdawy, Ahmed M

    2018-05-11

    The justified continuous emerging of new β-lactam antibiotics provokes the need for developing suitable analytical methods that accelerate and facilitate their analysis. A face central composite experimental design was adopted using different levels of phosphate buffer pH, acetonitrile percentage at zero time and after 15 min in a gradient program to obtain the optimum chromatographic conditions for the elution of 31 β-lactam antibiotics. Retention factors were used as the target property to build two QSRR models utilizing the conventional forward selection and the advanced nature-inspired firefly algorithm for descriptor selection, coupled with multiple linear regression. The obtained models showed high performance in both internal and external validation indicating their robustness and predictive ability. Williams-Hotelling test and student's t-test showed that there is no statistical significant difference between the models' results. Y-randomization validation showed that the obtained models are due to significant correlation between the selected molecular descriptors and the analytes' chromatographic retention. These results indicate that the generated FS-MLR and FFA-MLR models are showing comparable quality on both the training and validation levels. They also gave comparable information about the molecular features that influence the retention behavior of β-lactams under the current chromatographic conditions. We can conclude that in some cases simple conventional feature selection algorithm can be used to generate robust and predictive models comparable to that are generated using advanced ones. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Use of surfactants for the remediation of contaminated soils: a review.

    Science.gov (United States)

    Mao, Xuhui; Jiang, Rui; Xiao, Wei; Yu, Jiaguo

    2015-03-21

    Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Application of peptide gemini surfactants as novel solubilization surfactants for photosystems I and II of cyanobacteria.

    Science.gov (United States)

    Koeda, Shuhei; Umezaki, Katsunari; Noji, Tomoyasu; Ikeda, Atsushi; Kawakami, Keisuke; Kondo, Masaharu; Yamamoto, Yasushi; Shen, Jian-Ren; Taga, Keijiro; Dewa, Takehisa; Ito, Shigeru; Nango, Mamoru; Tanaka, Toshiki; Mizuno, Toshihisa

    2013-09-17

    We designed novel peptide gemini surfactants (PG-surfactants), DKDKC12K and DKDKC12D, which can solubilize Photosystem I (PSI) of Thermosynecoccus elongatus and Photosystem II (PSII) of Thermosynecoccus vulcanus in an aqueous buffer solution. To assess the detailed effects of PG-surfactants on the original supramolecular membrane protein complexes and functions of PSI and PSII, we applied the surfactant exchange method to the isolated PSI and PSII. Spectroscopic properties, light-induced electron transfer activity, and dynamic light scattering measurements showed that PSI and PSII could be solubilized not only with retention of the original supramolecular protein complexes and functions but also without forming aggregates. Furthermore, measurement of the lifetime of light-induced charge-separation state in PSI revealed that both surfactants, especially DKDKC12D, displayed slight improvement against thermal denaturation below 60 °C compared with that using β-DDM. This degree of improvement in thermal resistance still seems low, implying that the peptide moieties did not interact directly with membrane protein surfaces. By conjugating an electron mediator such as methyl viologen (MV(2+)) to DKDKC12K (denoted MV-DKDKC12K), we obtained derivatives that can trap the generated reductive electrons from the light-irradiated PSI. After immobilization onto an indium tin oxide electrode, a cathodic photocurrent from the electrode to the PSI/MV-DKDKC12K conjugate was observed in response to the interval of light irradiation. These findings indicate that the PG-surfactants DKDKC12K and DKDKC12D provide not only a new class of solubilization surfactants but also insights into designing other derivatives that confer new functions on PSI and PSII.

  8. Rheology of cellulose nanofibrils in the presence of surfactants.

    Science.gov (United States)

    Quennouz, Nawal; Hashmi, Sara M; Choi, Hong Sung; Kim, Jin Woong; Osuji, Chinedum O

    2016-01-07

    Cellulose nanofibrils (CNFs) present unique opportunities for rheology modification in complex fluids. Here we systematically consider the effect of ionic and non-ionic surfactants on the rheology of dilute CNF suspensions. Neat suspensions are transparent yield-stress fluids which display strong shear thinning and power-law dependence of modulus on concentration, G' ∼ c(2.1). Surfactant addition below a critical mass concentration cc produces an increase in the gel modulus with retention of optical clarity. Larger than critical concentrations induce significant fibril aggregation leading to the loss of suspension stability and optical clarity, and to aggregate sedimentation. The critical concentration was the lowest for a cationic surfactant (DTAB), cc ≈ 0.08%, while suspension stability was retained for non-ionic surfactants (Pluronic F68, TX100) at concentrations up to 8%. The anionic surfactant SDS led to a loss of stability at cc ≈ 1.6% whereas suspension stability was not compromised by anionic SLES up to 8%. Dynamic light scattering data are consistent with a scenario in which gel formation is driven by micelle-nanofibril bridging mediated by associative interactions of ethoxylated surfactant headgroups with the cellulose fibrils. This may explain the strong difference between the properties of SDS and SLES-modified suspensions. These results have implications for the use of CNFs as a rheology modifier in surfactant-containing systems.

  9. 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

  10. Surfactants in the environment.

    Science.gov (United States)

    Ivanković, Tomislav; Hrenović, Jasna

    2010-03-01

    Surfactants are a diverse group of chemicals that are best known for their wide use in detergents and other cleaning products. After use, residual surfactants are discharged into sewage systems or directly into surface waters, and most of them end up dispersed in different environmental compartments such as soil, water or sediment. The toxic effects of surfactants on various aquatic organisms are well known. In general, surfactants are present in the environment at levels below toxicity and in Croatia below the national limit. Most surfactants are readily biodegradable and their amount is greatly reduced with secondary treatment in wastewater treatment plants. The highest concern is the release of untreated wastewater or wastewater that has undergone primary treatment alone. The discharge of wastewater polluted with massive quantities of surfactants could have serious effects on the ecosystem. Future studies of surfactant toxicities and biodegradation are necessary to withdraw highly toxic and non-biodegradable compounds from commercial use and replace them with more environmentally friendly ones.

  11. Use of surfactants for the remediation of contaminated soils: A review

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Xuhui, E-mail: clab@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Jiang, Rui; Xiao, Wei [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2015-03-21

    Highlights: • The recent advances in use of surfactant for soil remediation are reviewed. • The mechanisms of surfactant-based soil remediation are discussed. • A review on the application of different types of surfactants is made. • The future research direction of surfactant-based technologies is suggested. - Abstract: Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation.

  12. Use of surfactants for the remediation of contaminated soils: A review

    International Nuclear Information System (INIS)

    Mao, Xuhui; Jiang, Rui; Xiao, Wei; Yu, Jiaguo

    2015-01-01

    Highlights: • The recent advances in use of surfactant for soil remediation are reviewed. • The mechanisms of surfactant-based soil remediation are discussed. • A review on the application of different types of surfactants is made. • The future research direction of surfactant-based technologies is suggested. - Abstract: Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation

  13. Surfactant Effects on Lipid-Based Vesicles Properties.

    Science.gov (United States)

    Bnyan, Ruba; Khan, Iftikhar; Ehtezazi, Touraj; Saleem, Imran; Gordon, Sarah; O'Neill, Francis; Roberts, Matthew

    2018-01-11

    Understanding the effect of surfactant properties is critical when designing vesicular delivery systems. This review evaluates previous studies to explain the influence of surfactant properties on the behavior of lipid vesicular systems, specifically their size, charge, stability, entrapment efficiency, pharmacokinetics, and pharmacodynamics. Generally, the size of vesicles decreases by increasing the surfactant concentration, carbon chain length, the hydrophilicity of the surfactant head group, and the hydrophilic-lipophilic balance. Increasing surfactant concentration can also lead to an increase in charge, which in turn reduces vesicle aggregation and enhances the stability of the system. The vesicles' entrapment efficiency not only depends on the surfactant properties but also on the encapsulated drug. For example, the encapsulation of a lipophilic drug could be enhanced by using a surfactant with a low hydrophilic-lipophilic balance value. Moreover, the membrane permeability of vesicles depends on the surfactant's carbon chain length and transition temperature. In addition, surfactants have a clear influence on pharmacokinetics and pharmacodynamics such as sustaining drug release, enhancing the circulation time of vesicles, improving targeting and cellular uptake. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  14. Metathesis depolymerizable surfactants

    Science.gov (United States)

    Jamison, Gregory M [Albuquerque, NM; Wheeler, David R [Albuquerque, NM; Loy, Douglas A [Tucson, AZ; Simmons, Blake A [San Francisco, CA; Long, Timothy M [Evanston, IL; McElhanon, James R [Manteca, CA; Rahimian, Kamyar [Albuquerque, NM; Staiger, Chad L [Albuquerque, NM

    2008-04-15

    A class of surfactant molecules whose structure includes regularly spaced unsaturation in the tail group and thus, can be readily decomposed by ring-closing metathesis, and particularly by the action of a transition metal catalyst, to form small molecule products. These small molecules are designed to have increased volatility and/or enhanced solubility as compared to the original surfactant molecule and are thus easily removed by solvent extraction or vacuum extraction at low temperature. By producing easily removable decomposition products, the surfactant molecules become particularly desirable as template structures for preparing meso- and microstructural materials with tailored properties.

  15. Surfactants, interfaces and pores : a theoretical study

    NARCIS (Netherlands)

    Huinink, H.

    1998-01-01

    The aim of this study was to investigate the behavior of surfactants in porous media by theoretical means. The influence of curvature of a surface on the adsorption has been studied with a mean field lattice (MFL) model, as developed by Scheutjens and Fleer. An analytical theory has been

  16. Effect of surfactant for magnetic properties of iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Haracz, S. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Hilgendorff, M. [Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany); Rybka, J.D. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Giersig, M. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany)

    2015-12-01

    Highlights: • Dynamic behavior of magnetic nanoparticles. • Synthesis of iron oxide nanoparticles. • Effect of surfactant for magnetic properties. - Abstract: For different medical applications nanoparticles (NPs) with well-defined magnetic properties have to be used. Coating ligand can change the magnetic moment on the surface of nanostructures and therefore the magnetic behavior of the system. Here we investigated magnetic NPs in a size of 13 nm conjugated with four different kinds of surfactants. The surface anisotropy and the magnetic moment of the system were changed due to the presence of the surfactant on the surface of iron oxide NPs.

  17. Effect of surfactant for magnetic properties of iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Haracz, S.; Hilgendorff, M.; Rybka, J.D.; Giersig, M.

    2015-01-01

    Highlights: • Dynamic behavior of magnetic nanoparticles. • Synthesis of iron oxide nanoparticles. • Effect of surfactant for magnetic properties. - Abstract: For different medical applications nanoparticles (NPs) with well-defined magnetic properties have to be used. Coating ligand can change the magnetic moment on the surface of nanostructures and therefore the magnetic behavior of the system. Here we investigated magnetic NPs in a size of 13 nm conjugated with four different kinds of surfactants. The surface anisotropy and the magnetic moment of the system were changed due to the presence of the surfactant on the surface of iron oxide NPs.

  18. Phosphine oxide surfactants revisited.

    Science.gov (United States)

    Stubenrauch, Cosima; Preisig, Natalie; Laughlin, Robert G

    2016-04-01

    This review summarizes everything we currently know about the nonionic surfactants alkyl dimethyl (C(n)DMPO) and alkyl diethyl (C(n)DEPO) phosphine oxide (PO surfactants). The review starts with the synthesis and the general properties (Section 2) of these compounds and continues with their interfacial properties (Section 3) such as surface tension, surface rheology, interfacial tension and adsorption at solid surfaces. We discuss studies on thin liquid films and foams stabilized by PO surfactants (Section 4) as well as studies on their self-assembly into lyotropic liquid crystals and microemulsions, respectively (Section 5). We aim at encouraging colleagues from both academia and industry to take on board PO surfactants whenever possible and feasible because of their broad variety of excellent properties. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Effects of anthropogenic surfactants on the conversion of marine dissolved organic carbon and microgels.

    Science.gov (United States)

    Shiu, Ruei-Feng; Lee, Chon-Lin

    2017-04-15

    The possible impact of three types of anthropogenic surfactants on the ability of marine dissolved organic carbon (DOC) to form self-assembled microgels was evaluated. The behavior of existing native microgels was also examined in the presence of surfactants. These results reveal that the release of surfactants even at low concentrations into the aquatic environment could effectively hinder the self-assembly of DOC polymers. The extent of the size reduction had the following order: anionic, cationic, and non-ionic. Furthermore, charged surfactants can disrupt existing native microgels, converting large assemblies into smaller particles. One possible mechanisms is that surfactants are able to enhance the stability of DOC polymers and disrupt aggregates due to their surface charges and protein-denaturing activities. These findings suggest that the ecological system is altered by anthropogenic surfactants, and provide useful information for ecological assessments of different types of surfactants and raise warnings about surfactant applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Whitefly feeding behavior and retention of a foregut-borne crinivirus exposed to artificial diets with different pH values.

    Science.gov (United States)

    Zhou, Jaclyn S; Chen, Angel Y S; Drucker, Martin; Lopez, Nicole H; Carpenter, Alyssa; Ng, James C K

    2017-12-01

    Transmission of plant viruses by phytophagous hemipteran insects encompasses complex interactions underlying a continuum of processes involved in virus acquisition, retention and inoculation combined with vector feeding behavior. Here, we investigated the effects of dietary pH on whitefly (Bemisia tabaci) feeding behavior and release of Lettuce infectious yellows virus (LIYV) virions retained in the vector's foregut. Electrical penetration graph analysis revealed that variables associated with whitefly probing and ingestion did not differ significantly in pH (4, 7.4, and 9) adjusted artificial diets. To investigate virus retention and release, whiteflies allowed to acquire LIYV virions in a pH 7.4 artificial diet were fed pH 4, 7.4, or 9 virion-free artificial (clearing) diets. Immunofluorescent localization analyses indicated that virions remained bound to the foreguts of approximately 20%-24% of vectors after they fed on each of the 3 pH-adjusted clearing diets. When RNA preparations from the clearing diets were analyzed by reverse transcription (RT) nested-PCR and, in some cases, real-time qPCR, successful amplification of LIYV-specific sequence was infrequent but consistently repeatable for the pH 7.4 diet but never observed for the pH 4 and 9 diets, suggesting a weak pH-dependent effect for virion release. Viruliferous vectors that fed on each of the 3 pH-adjusted clearing diets transmitted LIYV to virus-free plants. These results suggest that changes in pH values alone in artificial diet do not result in observable changes in whitefly feeding behaviors, an observation that marks a first in the feeding of artificial diet by whitefly vectors; and that there is a potential causal and contingent relationship between the pH in artificial diet and the release/inoculation of foregut bound virions. © 2017 Institute of Zoology, Chinese Academy of Sciences.

  1. American Recovery and Reinvestment Act of 2009. Interim Report on Customer Acceptance, Retention, and Response to Time-Based Rates from the Consumer Behavior Studies

    Energy Technology Data Exchange (ETDEWEB)

    Cappers, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hans, Liesel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Scheer, Richard [Scheer Ventures, Takoma Park, MD (United States)

    2015-06-01

    Time-based rate programs1, enabled by utility investments in advanced metering infrastructure (AMI), are increasingly being considered by utilities as tools to reduce peak demand and enable customers to better manage consumption and costs. There are several customer systems that are relatively new to the marketplace and have the potential for improving the effectiveness of these programs, including in-home displays (IHDs), programmable communicating thermostats (PCTs), and web portals. Policy and decision makers are interested in more information about customer acceptance, retention, and response before moving forward with expanded deployments of AMI-enabled new rates and technologies. Under the Smart Grid Investment Grant Program (SGIG), the U.S. Department of Energy (DOE) partnered with several utilities to conduct consumer behavior studies (CBS). The goals involved applying randomized and controlled experimental designs for estimating customer responses more precisely and credibly to advance understanding of time-based rates and customer systems, and provide new information for improving program designs, implementation strategies, and evaluations. The intent was to produce more robust and credible analysis of impacts, costs, benefits, and lessons learned and assist utility and regulatory decision makers in evaluating investment opportunities involving time-based rates. To help achieve these goals, DOE developed technical guidelines to help the CBS utilities estimate customer acceptance, retention, and response more precisely.

  2. Effects of functional monomers on retention behavior of small and large molecules in monolithic capillary columns at isocratic and gradient conditions.

    Science.gov (United States)

    Urban, Jiří; Jandera, Pavel; Langmaier, Pavel

    2011-08-01

    The polarity of (poly)methacrylate monolithic capillary columns was varied by using alkylmethacrylate monomers with butyl, cyclohexyl, 2-ethylhexyl, lauryl, and stearyl functional groups in the polymerization mixture. The hydrodynamic properties, as well as the retention characteristics in RP-LC of small molecules (alkylbenzenes) and of proteins under gradient elution conditions were studied. The RP selectivity depends on the type of alkyl chain in methacrylate monomer; however, there was no direct correlation between the size of the monomer molecule and methylene or aromatic selectivity of the monlithic column. The lowest selectivity was found for column based on lauryl methacrylate monomer. On the other hand, butyl methacrylate column shows high phenyl selectivity and the column with stearyl methacrylate possesses the highest methylene selectivity for small molecules. The retention increases with longer alkyl chain in methacrylate monomer, especially for high molar mass proteins on all prepared columns and showed gradient elution behavior of proteins in agreement with the linear solvent strength gradient model. The poly(laurylmethacrylate) column showed lowest hydrophobicity but best efficiency for proteins of all columns tested. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. The effects of forced-egg retention on the blood-feeding behavior and reproductive potential of Culex pipiens (Diptera: Culicidae).

    Science.gov (United States)

    Johnson, Brian J; Fonseca, Dina M

    2014-07-01

    High rates of West Nile virus (WNV) transmission to humans are associated with exceptionally hot and dry summers. This is paradoxical since the eggs of Culex vectors of WNV depend on the persistence of containers with water, which decline during droughts. We examined the effects of forced-egg retention on the reproductive success of female Culex pipiens as well as behavioral responses, such as likelihood of secondary blood meals. As controls we examined the effects of female age and delayed mating. We found that early mating is essential to achieve reproductive success and, consistent with an "all-or-none" ovipositing strategy, C. pipiens females are able to retain considerable reproductive potential while searching for oviposition sites. Specifically, although forced-egg retention resulted in significant decreases in fitness, the decline was moderate for 5 weeks and most can be accounted for by increases in female age. Consequently, no females took blood more than once per gonotrophic cycle, which eliminates the possibility that heightened vectorial capacity due to multiple blood-feedings increases WNV transmission during periods of drought. Instead, our findings suggest that during droughts populations of C. pipiens have time to locate the remaining water holes, which are associated with human populations and WNV-competent bird species. Copyright © 2014. Published by Elsevier Ltd.

  4. Identification of phases of various oil, surfactant/ co-surfactants and water system by ternary phase diagram.

    Science.gov (United States)

    Syed, Haroon K; Peh, Kok K

    2014-01-01

    The objective of this study was to select appropriate surfactants or blends of surfactants and oil to study the ternary phase diagram behavior and identify various phases obtained from the oil and surfactant/surfactant mixture combinations of different HLB. The phases include conventional emulsion, gel/viscous and transparent/translucent microemulsion. Pseudoternary phase diagrams of water, oil and S/Smix of various HLB values range of 9.65-15 were constructed by using water titration method at room temperature. Visual analysis, conductivity and dye dilution test (methylene blue) were performed after each addition and mixing of water, to identify phases as microemulsion, o/w or w/o emulsion (turbid/milky) and transparent gel/turbid viscous. High gel or viscous area was obtained with Tween 80 and surfactant mixture of Tween 80 and Span 80 with all oils. The results indicated that non-ionic surfactants and PG of different HLB values exhibited different pseudoternary phase diagram characteristics but no microemulsions originated from mineral and olive oils. The w/o emulsion occupied a large area in the ternary phase triangle when HLB value of the surfactant/Smix decreased. The o/w emulsion area was large with increasing HLB value of surfactant/Smix.

  5. Performance improvement of ionic surfactant flooding in carbonate rock samples by use of nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Ahmadi

    2016-07-01

    Full Text Available Abstract Various surfactants have been used in upstream petroleum processes like chemical flooding. Ultimately, the performance of these surfactants depends on their ability to reduce the interfacial tension between oil and water. The surfactant concentration in the aqueous solution decreases owing to the loss of the surfactant on the rock surface in the injection process. The main objective of this paper is to inhibit the surfactant loss by means of adding nanoparticles. Sodium dodecyl sulfate and silica nanoparticles were used as ionic surfactant and nanoparticles in our experiments, respectively. AEROSIL® 816 and AEROSIL® 200 are hydrophobic and hydrophilic nanoparticles. To determine the adsorption loss of the surfactant onto rock samples, a conductivity approach was used. Real carbonate rock samples were used as the solid phase in adsorption experiments. It should be noted that the rock samples were water wet. This paper describes how equilibrium adsorption was investigated by examining adsorption behavior in a system of carbonate sample (solid phase and surfactant solution (aqueous phase. The initial surfactant and nanoparticle concentrations were 500–5000 and 500–2000 ppm, respectively. The rate of surfactant losses was extremely dependent on the concentration of the surfactant in the system, and the adsorption of the surfactant decreased with an increase in the nanoparticle concentration. Also, the hydrophilic nanoparticles are more effective than the hydrophobic nanoparticles.

  6. Biophysical inhibition of synthetic vs. naturally-derived pulmonary surfactant preparations by polymeric nanoparticles.

    Science.gov (United States)

    Beck-Broichsitter, Moritz; Ruppert, Clemens; Schmehl, Thomas; Günther, Andreas; Seeger, Werner

    2014-01-01

    Reasonable suspicion has accumulated that inhaled nano-scale particulate matter influences the biophysical function of the pulmonary surfactant system. Hence, it is evident to provide novel insights into the extent and mechanisms of nanoparticle-surfactant interactions in order to facilitate the fabrication of safe nanomedicines suitable for pulmonary applications. Negatively- and positively-charged poly(styrene) nanoparticles (diameters of ~100nm) served as model carriers. Nanoparticles were incubated with several synthetic and naturally-derived pulmonary surfactants to characterize the sensitivity of each preparation to biophysical inactivation. Changes in surface properties (i.e. adsorption and dynamic surface tension behavior) were monitored in a pulsating bubble surfactometer. Both nanoparticle formulations revealed a dose-dependent influence on the biophysical behavior of all investigated pulmonary surfactants. However, the surfactant sensitivity towards inhibition depended on both the carrier type, where negatively-charged nanoparticles showed increased inactivation potency compared to their positively-charged counterparts, and surfactant composition. Among the surfactants tested, synthetic mixtures (i.e. phospholipids, phospholipids supplemented with surfactant protein B, and Venticute®) were more susceptible to surface-activity inhibition as the more complex naturally-derived preparations (i.e. Alveofact® and large surfactant aggregates isolated from rabbit bronchoalveolar lavage fluid). Overall, nanoparticle characteristics and surfactant constitution both influence the extent of biophysical inhibition of pulmonary surfactants. © 2013.

  7. A Conceptual Framework for Barriers to the Recruitment and Retention of Rural CVD Participants in Behavior Intervention Trials.

    Science.gov (United States)

    Young, Lufei; Montgomery, Melody; Barnason, Sue; Schmidt, Cindy; Do, Van

    2015-08-01

    Rural residents diagnosed with cardiovascular disease (CVD) or with CVD-related risks are underrepresented in behavioral intervention trials based on an extensive review of published studies. The low participation rate of rural residents weakens both the internal and external validity of published studies. Moreover, compared to urban residents, limited research exists to describe the unique barriers that limit the participation of rural residents in behavioral intervention trials. The purpose of this review is to identify a conceptual framework (CF) underpinning common barriers faced by rural CVD patients to enroll in behavioral intervention trials. We conducted a literature review using several electronic databases to obtain a representative sample of research articles, synthesized the evidence, and developed a CF to explain the barriers that may affect the research participation rate of rural residents with CVD or related risks. We found our evidence-based CF well explained the barriers for rural CVD patients to take part in behavioral intervention trials. Besides contextual factors (i.e. patient, community and research levels), other common factors impacting rural patients' intent to enroll are lack of awareness and understanding about behavioral trials, limited support from their healthcare providers and social circles, unfavorable attitudes, and the lack of opportunity to participating research. The findings demonstrate the evidence-based model consisting of interlinked multi-level factors may help our understanding of the barriers encountered by rural CVD patients participating interventions to promote behavioral change. The implication for researchers is that identifying and developing strategies to overcome the barriers precedes conducting studies in rural communities.

  8. Transport, retention, and long-term release behavior of polymer-coated silver nanoparticles in saturated quartz sand: The impact of natural organic matters and electrolyte.

    Science.gov (United States)

    Hou, Jun; Zhang, Mingzhi; Wang, Peifang; Wang, Chao; Miao, Lingzhan; Xu, Yi; You, Guoxiang; Lv, Bowen; Yang, Yangyang; Liu, Zhilin

    2017-10-01

    This study investigated the transport and long-term release of stabilized silver nanoparticles (AgNPs), including polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) and bare AgNPs (Bare-AgNPs), in the presence of natural organic matters (NOMs; both humic acids (HA) and alginate (Alg)) and an electrolyte (Ca 2+ ) in a sand-packed column. Very low breakthrough rate (C/C 0 ) of AgNPs (below 0.04) occurred in the absence of NOM and the electrolyte. Increasing the concentration of NOM and decreasing the influent NOM solution's ionic strength (IS) reduced the retention of AgNPs. The reduced NP retention at high NOM and low IS was mainly attributed to the increased energy barrier between the AgNPs and the sand grain surface. Notably, the retention of PVP-AgNPs was enhanced at high Alg concentration and low IS, which mainly resulted from the improved hydrophobicity that could increase the interaction between the PVP-AgNPs and the collector. The total release amount of PVP-AgNPs (10.03%, 9.50%, 28.42%, 6.37%) and Bare-AgNPs (3.28%, 2.58%, 10.36%, 1.54%) were gained when exposed to four kinds of NOM solutions, including deionized water, an electrolyte solution (1 mM Ca 2+ ), HA with an electrolyte (1 mM Ca 2+ ), and a Alg (40 mg/L) solution with an electrolyte (1 mM Ca 2+ ). The long-term release of retained silver nanoparticles in the quartz sand was mostly through the form of released Ag NPs. The factors that increased the mobility of AgNPs in quartz sand could improve the release of the AgNPs. The release of AgNPs had no significant change in the presence Ca 2+ but were increased in the presence of HA. The Alg slightly decreased the release of AgNPs by increasing the hydrophobicity of AgNPs. The results of the study indicated that all the tested NOM and Ca 2+ have prominent influence on the transport and long-term release behavior of silver nanoparticles in saturated quartz sand. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. [Influences of ion-suppressors on retention behaviors of nine food additives in reversed-phase high performance liquid chromatographic separation].

    Science.gov (United States)

    Zhao, Yonggang; Chen, Xiaohong; Li, Xiaoping; Yao, Shanshan; Jin, Micong

    2011-10-01

    The influences of ion-suppressors on retention behaviors of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in reversed-phase high performance liquid chromatographic (RP-HPLC) separation were investigated. The organic modification effects of acids, i. e. , trifluoroacetic acid (TFA) and buffer salts, i. e. , TFA-ammonium acetate (AmAc) were studied emphatically. The relationships between retention factors of solutes and volume percentages of ion-suppressors in the mobile phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, separately. The separation of nine food additives was completed by a gradient elution with acetonitrile-TFA (0.01%, v/v)-AmAc (2. 5 mmol/L) aqueous solution as the mobile phases. An RP-HPLC method was established for the simultaneous determination of nine food additives in red wine. In the range of 10. 0 - 100. 0 mg/L, nine food additives showed good linearity with the correlation coefficients ( r2 ) larger than 0. 999 1. The limits of detection (LODs) were in the range of 0. 33 - 2. 36 mg/L and the limits of quantification (LOQs) were in the range of 1. 11 - 7. 80 mg/L. The spiked recoveries were between 87. 61% and 108. 4% with the relative standard deviations (RSDs) of 2. 2% -9. 4%. These results are of referential significance for the rapid establishment and accu- rate optimization of RP-HPLC separation for the simultaneous determination of food additives in other foods.

  10. Diseases of Pulmonary Surfactant Homeostasis

    Science.gov (United States)

    Whitsett, Jeffrey A.; Wert, Susan E.; Weaver, Timothy E.

    2015-01-01

    Advances in physiology and biochemistry have provided fundamental insights into the role of pulmonary surfactant in the pathogenesis and treatment of preterm infants with respiratory distress syndrome. Identification of the surfactant proteins, lipid transporters, and transcriptional networks regulating their expression has provided the tools and insights needed to discern the molecular and cellular processes regulating the production and function of pulmonary surfactant prior to and after birth. Mutations in genes regulating surfactant homeostasis have been associated with severe lung disease in neonates and older infants. Biophysical and transgenic mouse models have provided insight into the mechanisms underlying surfactant protein and alveolar homeostasis. These studies have provided the framework for understanding the structure and function of pulmonary surfactant, which has informed understanding of the pathogenesis of diverse pulmonary disorders previously considered idiopathic. This review considers the pulmonary surfactant system and the genetic causes of acute and chronic lung disease caused by disruption of alveolar homeostasis. PMID:25621661

  11. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2003-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. 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%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have acquired field oil and core samples and field brine compositions from Marathon. We have conducted preliminary adsorption and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Receding contact angles increase with surfactant adsorption. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  12. Retention capacity of random surfaces.

    Science.gov (United States)

    Knecht, Craig L; Trump, Walter; Ben-Avraham, Daniel; Ziff, Robert M

    2012-01-27

    We introduce a "water retention" model for liquids captured on a random surface with open boundaries and investigate the model for both continuous and discrete surface heights 0,1,…,n-1 on a square lattice with a square boundary. The model is found to have several intriguing features, including a nonmonotonic dependence of the retention on the number of levels: for many n, the retention is counterintuitively greater than that of an (n+1)-level system. The behavior is explained using percolation theory, by mapping it to a 2-level system with variable probability. Results in one dimension are also found.

  13. Studies on Anionic Surfactant Structure in the Aggregation with (Hydroxypropylcellulose

    Directory of Open Access Journals (Sweden)

    Ricardo M. de Martins

    2002-01-01

    Full Text Available Fluorescence probing, viscosity and light scattering measurements have been combined to study the aggregation of different anionic surfactants mainly in dilute solutions (0.5% w/v of (hydroxypropylcellulose (HPC MW 173,000, in moderate ionic strength (NaCl 0.1 mol.L-1. The set of surfactants includes natural cholesterol derivatives, sodium cholate (CS and sodium deoxycholate (DC, and the alkylsulphate, sodium dodecylsulphate (SDS. At 298 K the critical surfactant concentration related to aggregate/HPC formation (C1 decreases for SDS and DC whereas it increases slightly for CS. At 312 K the C1 values for CS and DC are slightly shifted toward higher values whereas it is not changed for SDS. All surfactant/HPC systems increase C1 values as the HPC concentration increases to 1.2%. Above C1 the viscosity increases for all surfactant/HPC systems but it is sharper in the increasing order CS, DC and SDS. The hydrodynamic behavior indicates that CS induces higher diffusion to HPC than SDS and DC. The aggregation in the surfactant/HPC systems is analyzed through the feature of surfactant/aggregate structure (size, charge density, etc.

  14. Coacervation with surfactants: From single-chain surfactants to gemini surfactants.

    Science.gov (United States)

    Zhao, Weiwei; Wang, Yilin

    2017-01-01

    Coacervation is a spontaneous process during which a colloidal dispersion separates into two immiscible liquid phases: a colloid-rich liquid phase in equilibrium with a diluted phase. Coacervation is usually divided into simple coacervation and complex coacervation according to the number of components. Surfactant-based coacervation normally contains traditional single-chain surfactants. With the development of surfactants, gemini surfactants with two amphiphilic moieties have been applied to form coacervation. This review summarizes the development of simple coacervation and complex coacervation in the systems of single-chain surfactants and gemini surfactants. Simple coacervation in surfactant solutions with additives or at elevated temperature and complex coacervation in surfactant/polymer mixtures by changing charge densities, molecular weight, ionic strength, pH, or temperature are reviewed. The comparison between gemini surfactants and corresponding monomeric single-chain surfactants reveals that the unique structures of gemini surfactants endow them with higher propensity to generate coacervation. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Perfluorinated Alcohols Induce Complex Coacervation in Mixed Surfactants.

    Science.gov (United States)

    Jenkins, Samuel I; Collins, Christopher M; Khaledi, Morteza G

    2016-03-15

    Recently, we reported a unique and nearly ubiquitous phenomenon of inducing simple and complex coacervation in solutions of a broad variety of individual and mixed amphiphiles and over a wide range of concentrations and mole fractions. This paper describes a novel type of biphasic separation in aqueous solutions of mixed cationic-anionic (catanionic) surfactants induced by hexafluoroisopropanol (HFIP). The test cases included mixtures of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) (surfactants with different carbon chain lengths) as well as dodecyltrimethylammonium bromide (DTAB) with SDS (surfactants with the same carbon chain lengths). The CTAB-SDS-HFIP coacervate systems can be produced at many different mole ratios of surfactant, but DTAB-SDS-HFIP formed only coacervates at equimolar (1:1) mole ratios of DTAB and SDS. The phase-transition behavior of both systems was studied over a wide range of surfactant and HFIP concentrations at the stoichiometric (1:1) mole ratio of cationic/anionic surfactants. The chemical compositions of each of the two phases (aqueous-rich and coacervate phases) were studied with regard to the concentrations of HFIP, water, and individual surfactants. It is revealed that the surfactant-rich phase (coacervate phase) contains a large percentage of fluoroalcohol relative to the aqueous phase and is enriched in both surfactants but contains a small percentage of water. Surprisingly, the concentration of water in the coacervate phase increases as the total HFIP concentration is increased while the concentration of HFIP in the coacervate phase remains relatively constant, which means a larger amount of water associated with HFIP molecules is extracted into the coacervate phase, which results in the growth of the phase. The volume of the coacervate phase increases with an increase in surfactant concentration and total HFIP %. The coacervate phase is highly enriched in the two amphiphilic ions (DTA(+) and DS

  16. Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Paulo B. [Univ. of California, Berkeley, CA (United States)

    1998-12-14

    Surfactants are widely used to modify physical and chemical properties of interfaces. They play an important role in many technological problems. Surfactant monolayer are also of great scientific interest because they are two-dimensional systems that may exhibit a very rich phase transition behavior and can also be considered as a model system for biological interfaces. In this Thesis, we use a second-order nonlinear optical technique (Sum-Frequency Generation - SFG) to obtain vibrational spectra of surfactant monolayer at Iiquidhapor and solid/liquid interfaces. The technique has several advantages: it is intrinsically surface-specific, can be applied to buried interfaces, has submonolayer sensitivity and is remarkably sensitive to the confirmational order of surfactant monolayers.

  17. 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.

  18. Surfactants at the Design Limit.

    Science.gov (United States)

    Czajka, Adam; Hazell, Gavin; Eastoe, Julian

    2015-08-04

    This article analyzes how the individual structural elements of surfactant molecules affect surface properties, in particular, the point of reference defined by the limiting surface tension at the aqueous cmc, γcmc. Particular emphasis is given to how the chemical nature and structure of the hydrophobic tails influence γcmc. By comparing the three different classes of surfactants, fluorocarbon, silicone, and hydrocarbon, a generalized surface packing index is introduced which is independent of the chemical nature of the surfactants. This parameter ϕcmc represents the volume fraction of surfactant chain fragments in a surface film at the aqueous cmc. It is shown that ϕcmc is a useful index for understanding the limiting surface tension of surfactants and can be useful for designing new superefficient surfactants.

  19. Properties of binary surfactant systems of nonionic surfactants C12E10, C12E23, and C12E42 with a cationic gemini surfactant in aqueous solutions.

    Science.gov (United States)

    Hu, Changchao; Li, Rongqiang; Yang, Hui; Wang, Jinben

    2011-04-15

    Properties of binary surfactant systems of nonionic surfactants poly(ethylene oxide) (PEO) lauryl ethers (C(12)E(10), C(12)E(23), C(12)E(42)) with a cationic gemini surfactant, butanediyl-α,ω-bis(tetradecyldimethylammonium bromide) (14-4-14), have been investigated by Steady-state Fluorescence (FL), zeta potential, Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), Cryogenic Transmission Electron Microscopy (CryoTEM), and X-ray Diffraction (XRD). Through FL measurements, critical micelle concentration (CMC) of the three binary systems for different mixing mole fractions is determined and the values fall between those of pure constituent surfactants. Ideal CMC (CMC(ideal)), mole fraction in aggregates (X), interaction parameter (β), activity coefficients (f(1) and f(2)), and excess free energy of mixing (ΔG(ex)) have been calculated. All these parameters indicate nonideal behavior and synergistic interactions between the constituent surfactants, which is explained in terms of electrostatic attraction between headgroups of constituent surfactants and reduction of electrostatic repulsion between headgroups of 14-4-14 due to the presence of nonionic surfactants. DLS, TEM and CryoTEM results show that nonionic surfactants facilitate the formation of larger aggregates. Micelles and vesicles in larger size compared with those of 14-4-14 coexist in the mixed solutions. Both surfactant composition and PEO chain length are found to play a strong effect on the properties of the binary systems. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Transport, retention, and long-term release behavior of ZnO nanoparticle aggregates in saturated quartz sand: Role of solution pH and biofilm coating

    Science.gov (United States)

    The transport, retention, and long-term fate of zinc oxide nanoparticles (ZnO-NPs) were investigated in saturated, bare and biofilm (Pseudomonas putida) coated sand packed columns. Almost complete retention of ZnO-NPs occurred in bare and biofilm coated sand when the influent solution pH was 9 and t...

  1. 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

  2. Modifications in structure and interaction of nanoparticle-protein-surfactant complexes in electrolyte solution

    Science.gov (United States)

    Mehan, Sumit; Kumar, S.; Aswal, V. K.; Schweins, R.

    2016-05-01

    SANS experiments of three-component system of anionic silica nanoparticles, anionic BSA protein and anionic SDS surfactants have been carried out without and with electrolyte in aqueous solution. In both the cases, the interaction of surfactant with protein results in formation of bead-necklace structure of protein-surfactant complexes in solution. These protein-surfactant complexes interact very differently with nanoparticles in absence and presence of electrolyte. In absence of electrolyte, nanoparticles remain in dispersed phase in solution, whereas with the addition of electrolyte the nanoparticles fractal aggregates are formed. SANS describes the phase behavior to be governed by competition of electrostatic and depletion interactions among the components solution.

  3. Synthesis and properties of di-n-dodecyl alpha,omega-alkyl bisphosphate surfactants

    NARCIS (Netherlands)

    Duivenvoorde, F.L.; Feiters, M.C.; Van der Gaast, S.J.; Engberts, J.B.F.N.

    1997-01-01

    Three gemini and two bolaform bisphosphate surfactants of the type 12-s-12, with s = 6, 8, 12, 18, and 24 carbon atoms, have been synthesized and their aggregation behavior has been studied. The bolaform surfactants 12-18-12 and 12-24-12 were found to form vesicles in aqueous solution, as indicated

  4. Modeling the effects of surfactant, hardness, and natural organic matter on deposition and mobility of silver nanoparticles in saturated porous media.

    Science.gov (United States)

    Park, Chang Min; Heo, Jiyong; Her, Namguk; Chu, Kyoung Hoon; Jang, Min; Yoon, Yeomin

    2016-10-15

    This study aims to provide insights into the mechanisms governing the deposition and retention of silver nanoparticles (AgNPs) in saturated porous media. Column experiments were conducted with quartz sand under saturated conditions to investigate the deposition kinetics of AgNPs, their mobility at different groundwater hardnesses (10-400 mg/L as CaCO3), and humic acid (HA, 0-50 mg/L as dissolved organic carbon [DOC]). An anionic surfactant, sodium dodecyl sulfate (SDS), was used as a dispersing agent to prepare a SDS-AgNPs suspension. The deposition kinetics of AgNPs were highly sensitive to the surfactant concentration, ionic strength, and cation type in solution. The breakthrough curves (BTCs) of SDS-AgNPs suggested that the transport and retention were influenced by groundwater hardness and HA. At low water hardness and high HA, high mobility of SDS-AgNPs was observed in saturated conditions. However, the retention of SDS-AgNPs increased substantially in very hard water with a low concentration of HA, because of a decreased primary energy barrier and the straining effect during the course of transport experiments. A modified clean-bed filtration theory and a two-site kinetic attachment model showed good fits with the BTCs of SDS-AgNPs. The fitted model parameters (katt and kstr) could be used successfully to describe that the retention behaviors were dominated by electrostatic and electrosteric repulsion, based on extended Derjaguin-Landau-Vaerwey-Overbeek calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. 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...

  6. Surfactant monitoring by foam generation

    Science.gov (United States)

    Mullen, Ken I.

    1997-01-01

    A device for monitoring the presence or absence of active surfactant or other surface active agents in a solution or flowing stream based on the formation of foam or bubbles is presented. The device detects the formation of foam with a light beam or conductivity measurement. The height or density of the foam can be correlated to the concentration of the active surfactant present.

  7. Managing retention.

    Science.gov (United States)

    Carter, Tony

    2007-01-01

    To build this process it is necessary to consult customers for preferences, build familiarity and knowledge to build a relationship and conduct business in a customized fashion. The process takes every opportunity to build customer satisfaction with each customer contact. It is an important process to have, since customers today are more demanding, sophisticated, educated and comfortable speaking to the company as an equal (Belk, 2003). Customers have more customized expectations so they want to be reached as individuals (Raymond and Tanner, 1994). Also, a disproportionate search for new business is costly. The cost to cultivate new customers is more than maintaining existing customers (Cathcart, 1990). Other reasons that customer retention is necessary is because many unhappy customers will never buy again from a company that dissatisfied them and they will communicate their displeasure to other people. These dissatisfied customers may not even convey their displeasure but without saying anything just stop doing business with that company, which may keep them unaware for some time that there is any problem (Cathcart, 1990).

  8. 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.

  9. Structural Studies of Protein-Surfactant Complexes

    International Nuclear Information System (INIS)

    Chodankar, S. N.; Aswal, V. K.; Wagh, A. G.

    2008-01-01

    The structure of protein-surfactant complexes of two proteins bovine serum albumin (BSA) and lysozyme in presence of anionic surfactant sodium dodecyl sulfate (SDS) has been studied using small-angle neutron scattering (SANS). It is observed that these two proteins form different complex structures with the surfactant. While BSA protein undergoes unfolding on addition of surfactant, lysozyme does not show any unfolding even up to very high surfactant concentrations. The unfolding of BSA protein is caused by micelle-like aggregation of surfactant molecules in the complex. On the other hand, for lysozyme protein there is only binding of individual surfactant molecules to protein. Lysozyme in presence of higher surfactant concentrations has protein-surfactant complex structure coexisting with pure surfactant micelles

  10. The Krafft temperature of surfactant solutions

    Directory of Open Access Journals (Sweden)

    Manojlović Jelena Ž.

    2012-01-01

    Full Text Available Our main motivation to revisit the solution properties of cetyltrimethylammonium bromide is related to the clear requirement for better control of the adsorption parameters to form uniform self-assembled monolayers on muscovite mica substrates. To readily monitor the temporal evolution of structural details in cetyltrimethylammonium bromide solutions, we realized a rather simple conductivity experiment. Conductivity measurements were carried out as a function of temperature, to look closer into the Krafft temperature behavior of this surfactant. We measured the electrical conductivity of different concentrations of aqueous cetyltrimethylammonium bromide solutions, below and above the critical micells concentration.

  11. Dysfunction of pulmonary surfactant mediated by phospholipid oxidation is cholesterol-dependent.

    Science.gov (United States)

    Al-Saiedy, Mustafa; Pratt, Ryan; Lai, Patrick; Kerek, Evan; Joyce, Heidi; Prenner, Elmar; Green, Francis; Ling, Chang-Chun; Veldhuizen, Ruud; Ghandorah, Salim; Amrein, Matthias

    2018-04-01

    Pulmonary surfactant forms a cohesive film at the alveolar air-lung interface, lowering surface tension, and thus reducing the work of breathing and preventing atelectasis. Surfactant function becomes impaired during inflammation due to degradation of the surfactant lipids and proteins by free radicals. In this study, we examine the role of reactive nitrogen (RNS) and oxygen (ROS) species on surfactant function with and without physiological cholesterol levels (5-10%). Surface activity was assessed in vitro in a captive bubble surfactometer (CBS). Surfactant chemistry, monolayer fluidity and thermodynamic behavior were also recorded before and after oxidation. We report that physiologic amounts of cholesterol combined with oxidation results in severe impairment of surfactant function. We also show that surfactant polyunsaturated phospholipids are the most susceptible to oxidative alteration. Membrane thermodynamic experiments showed significant surfactant film stiffening after free radical exposure in the presence of cholesterol. These results point to a previously unappreciated role for cholesterol in amplifying defects in surface activity caused by oxidation of pulmonary surfactant, a finding that may have implications for treating several lung diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Redox-triggered mixing and demixing of surfactants within assemblies formed in solution and at surfaces.

    Science.gov (United States)

    Smith, Timothy J; Wang, Chenxuan; Abbott, Nicholas L

    2017-09-15

    We report experiments that test the hypothesis that redox-triggered changes in the architectures of surfactants permit control of mixing of surfactants within assemblies. Specifically, we describe surface tension, light scattering, atomic force microscopy, and quartz crystal microbalance measurements that characterize the redox-dependent behaviors of cationic surfactants with a ferrocene group located either at the surfactant terminus (11-ferrocenylundecyl-trimethylammonium bromide; FTMA) or head (N,N-dimethylferrocenylmethyldecylammonium bromide; DMFA). In bulk solution, we find that reduced and oxidized FTMA do not mix within micellar assemblies but that reduced and oxidized DMFA do form mixed micelles. Because oxidized FTMA has the architecture of a bolaform surfactant whereas oxidized DMFA has a conventional surfactant architecture with a divalent head group, these results suggest that redox-triggered changes in molecular architecture permit control of the extent of mixing of surfactants in micellar assemblies in bulk solution. This conclusion receives further support from measurements performed with mixtures of dodecyltrimethylammonium bromide and FTMA, with FTMA in either reduced or oxidized states, and was found to extend to hemimicellar assemblies formed at hydrophobic solid surfaces but not to mixed monolayers formed at the surface of water. The latter is attributed to differences in the conformations of surfactants within monolayers and micellar assemblies. Overall, these results provide insight into the design of surfactant assemblies within which mixing can be controlled reversibly using redox processes. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. 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)

  14. The influence of nonionic surfactant Brij 30 on biodegradation of ...

    African Journals Online (AJOL)

    ONOS

    2010-09-06

    Sep 6, 2010 ... kinetic behaviors of toluene in a polyvinyl alcohol (PVA)/peat/KNO3/ (granular activated carbon) GAC composite bead biofilter ... The maximum elimination capacity decreased with increasing surfactant content. The addition of nonionic ... Chan and Peng, 2008). Toluene is a widely used industrial chemical.

  15. 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

  16. Significant effect of surfactant micelles on pH dependent fluorescent off-on-off behavior of Salicylaldehyde-2,4-Dinitrophenylhydrazone

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, Priyanka [Department of Chemistry, Gauhati University, Guwahati 781 014 (India); Das, Diganta K., E-mail: digkdas@yahoo.co [Department of Chemistry, Gauhati University, Guwahati 781 014 (India)

    2011-04-15

    The fluorescence response to pH of 2,4 dinitrophenolhydrazone in 1:1 CH{sub 3}OH:H{sub 2}O and micellar mediums-negatively charged sodium dodecylsulphate (SDS), positively charged cetyltrimethyl ammonium bromide (CTAB) and neutral Triton X-100 (TX-100), is reported. At pH 4.0 the fluorescence of the molecule can be switched 'on' by selecting CTAB as the solvent. At pH 6.0 if the medium is TX-100 the fluorescence is 'off', but remains 'on' for the other three solvents. At pH 8.0, fluorescence is 'on' in the solvents except CTAB. SDS and TX-100 switch the fluorescence 'on' at pH 13.0 but for the other two solvents the fluorescence is 'off'. - Research highlights: The fluorescence response to pH of Salicylaldehyde-2,4 Dinitrophenolhydrazone in 1:1 CH{sub 3}OH:H{sub 2}O and in positively charged cetyltrimethyl ammonium bromide (CTAB) micellar medium shows 'off-on-off' behavior. In negatively charged sodium dodecylsulphate (SDS) the response of fluorescence of Salicylaldehyde-2,4 Dinitrophenolhydrazone to pH is 'off-on-on' type while in neutral Triton X-100 it is 'off-on-1/2on' type. At a given pH, fluorescence of 2,4 dinitrophenolhydrazone can be made 'on' or 'off' by selecting an appropriate pH.

  17. Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery

    Energy Technology Data Exchange (ETDEWEB)

    P. Somasundaran

    2008-09-20

    Chemical EOR can be an effective method for increasing oil recovery and reducing the amount of produced water; however, reservoir fluids are chemically complex and may react adversely to the polymers and surfactants injected into the reservoir. While a major goal is to alter rock wettability and interfacial tension between oil and water, rock-fluid and fluid-fluid interactions must be understood and controlled to minimize reagent loss, maximize recovery and mitigate costly failures. The overall objective of this project was to elucidate the mechanisms of interactions between polymers/surfactants and the mineral surfaces responsible for determining the chemical loss due to adsorption and precipitation in EOR processes. The role of dissolved inorganic species that are dependent on the mineralogy is investigated with respect to their effects on adsorption. Adsorption, wettability and interfacial tension are studied with the aim to control chemical losses, the ultimate goal being to devise schemes to develop guidelines for surfactant and polymer selection in EOR. The adsorption behavior of mixed polymer/surfactant and surfactant/surfactant systems on typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) was correlated to their molecular structures, intermolecular interactions and the solution conditions such as pH and/or salinity. Predictive models as well as general guidelines for the use of polymer/surfactant surfactant/surfactant system in EOR have been developed The following tasks have been completed under the scope of the project: (1) Mineral characterization, in terms of SEM, BET, size, surface charge, and point zero charge. (2) Study of the interactions among typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) and surfactants and/or polymers in terms of adsorption properties that include both macroscopic (adsorption density, wettability) and microscopic (orientation

  18. Atrazine and Diuron partitioning within a soil-water-surfactant system

    Science.gov (United States)

    Wang, P.; Keller, A.

    2006-12-01

    The interaction between pesticide and soil and water is even more complex in the presence of surfactants. In this study, batch equilibrium was employed to study the sorption of surfactants and the partitioning behaviors of Atrazine and Diuron within a soil-water-surfactant system. Five soils and four surfactants (nonionic Triton- 100, cationic Benzalkonium Chloride (BC), anionic Linear Alkylbenzenesulfonate (LAS), and anionic Sodium Dodecyl Sulfate (SDS)) were used. All surfactant sorption isotherms exhibited an initial linear increase at low surfactant concentrations but reached an asymptotic value as the surfactant concentrations increased. Among the surfactants, BC had the highest sorption onto all soils, followed by Triton-100 and then by LAS and SDS, implying that the nature of the charge significantly influences surfactant sorption. Sorption of either Triton-100 or BC was highly correlated with soil Cation Exchange Capacity (CEC) while that of LAS and SDS was complicated by the presence of Ca2+ and Mg2+ in the aqueous phase and the CEC sites. Both LAS and SDS formed complexes with Ca2+ and Mg2+, resulting in a significant decrease in the detergency of the surfactants. At high surfactant concentrations and with micelles present in the aqueous phase, the micelles formed a more competitive partitioning site for the pesticides, resulting in less pesticide sorbed to the soil. At low Triton-100 and BC concentration, the sorption of the surfactants first resulted in less Atrazine sorption but more Diuron sorption, implying competition between the surfactants and Atrazine, which serves as an indirect evidence that there is a different sorption mechanism for Atrazine. Atrazine is a weak base and it protonates and becomes positively charged near particle surfaces where the pH is much lower than in the bulk solution. The protonated Atrazine may then be held on the CEC sites via electrostatic attraction. Triton-100, LAS and SDS sorbed on the soil showed similar

  19. Divertor retention for recycling impurities

    International Nuclear Information System (INIS)

    Krieger, K.; Roth, J.; Fussmann, G.

    1992-01-01

    As an important issue for fusion devices with divertor configurations the retention capability for both recycling and non-recycling impurities receives increasing interest. In the case of recycling, gaseous, impurities the retention capability is usually investigated by means of short impurity gas puffs into the plasma vessel and the analysis of the time dependence of the observed line radiation. The detailed understanding of the impurity transport processes related to the retention capability of a certain divertor structure will require modelling of the experimental results with 2D or 3D transport code simulations. However, for the comparison of the global behavior of different configurations a much simpler description of the divertor retention in terms of global time constants may be sufficient. We will give a summary of experimental results from ASDEX for the dependence of the retention capability on parameters like divertor plasma density and temperature and the distance along field lines between main plasma and divertor. In addition we will compare some of these results with similar experiments on DIIID. (author) 8 refs., 2 figs., 2 tabs

  20. Fuel nozzle tube retention

    Energy Technology Data Exchange (ETDEWEB)

    Cihlar, David William; Melton, Patrick Benedict

    2017-02-28

    A system for retaining a fuel nozzle premix tube includes a retention plate and a premix tube which extends downstream from an outlet of a premix passage defined along an aft side of a fuel plenum body. The premix tube includes an inlet end and a spring support feature which is disposed proximate to the inlet end. The premix tube extends through the retention plate. The spring retention feature is disposed between an aft side of the fuel plenum and the retention plate. The system further includes a spring which extends between the spring retention feature and the retention plate.

  1. Biomimicry of surfactant protein C.

    Science.gov (United States)

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

    2008-10-01

    Since the widespread use of exogenous lung surfactant to treat neonatal respiratory distress syndrome, premature infant survival and respiratory morbidity have dramatically improved. Despite the effectiveness of the animal-derived surfactant preparations, there still remain some concerns and difficulties associated with their use. This has prompted investigation into the creation of synthetic surfactant preparations. However, to date, no clinically used synthetic formulation is as effective as the natural material. This is largely because the previous synthetic formulations lacked analogues of the hydrophobic proteins of the lung surfactant system, SP-B and SP-C, which are critical functional constituents. As a result, recent investigation has turned toward the development of a new generation of synthetic, biomimetic surfactants that contain synthetic phospholipids along with a mimic of the hydrophobic protein portion of lung surfactant. In this Account, we detail our efforts in creating accurate mimics of SP-C for use in a synthetic surfactant replacement therapy. Despite SP-C's seemingly simple structure, the predominantly helical protein is extraordinarily challenging to work with given its extreme hydrophobicity and structural instability, which greatly complicates the creation of an effective SP-C analogue. Drawing inspiration from Nature, two promising biomimetic approaches have led to the creation of rationally designed biopolymers that recapitulate many of SP-C's molecular features. The first approach utilizes detailed SP-C structure-activity relationships and amino acid folding propensities to create a peptide-based analogue, SP-C33. In SP-C33, the problematic and metastable polyvaline helix is replaced with a structurally stable polyleucine helix and includes a well-placed positive charge to prevent aggregation. SP-C33 is structurally stable and eliminates the association propensity of the native protein. The second approach follows the same design

  2. Surfactant adsorption at the salt/water interface: comparing the conformation and interfacial water structure for selected surfactants.

    Science.gov (United States)

    Becraft, Kevin A; Richmond, Geraldine L

    2005-03-24

    We report in situ spectroscopic measurements monitoring the adsorption of a series of carboxylate surfactants onto the surface of the semisoluble, ionic solid fluorite (CaF2). We employ the surface-specific technique, vibrational sum-frequency spectroscopy (VSFS), to examine the effect that surfactant adsorption has on the bonding interactions and orientation of interfacial water molecules through the alteration of the electric properties in the interfacial region. In addition, we report on the chain length and headgroup dependence of the formation of hydrophobic self-assembled monolayers on the surface of the solid phase. Differences in chain length and headgroup functionality lead to large changes in the adsorption behavior and structuring of the monolayers formed and the interactions of interfacial water molecules with these monolayers. Fundamental studies such as these are essential for understanding the mechanisms involved in the surfactant adsorption process, information that is important for industrially relevant processes such as mineral ore flotation, waste processing, and petroleum recovery.

  3. The interaction of a model active pharmaceutical with cationic surfactant and the subsequent design of drug based ionic liquid surfactants.

    Science.gov (United States)

    Qamar, Sara; Brown, Paul; Ferguson, Steven; Khan, Rafaqat Ali; Ismail, Bushra; Khan, Abdur Rahman; Sayed, Murtaza; Khan, Asad Muhammad

    2016-11-01

    Interactions of active pharmaceutical ingredients (API) with surfactants remain an important research area due to the need to improve drug delivery systems. In this study, UV-Visible spectrophotometry was used to investigate the interactions between a model low molecular weight hydrophilic drug sodium valproate (SV) and cationic surfactant cetyltrimethylammonium bromide (CTAB). Changes in the spectra of SV were observed in pre- and post-micellar concentrations of CTAB. The binding constant (Kb) values and the number of drug molecules encapsulated per micelle were calculated, which posed the possibility of mixed micelle formation and strong complexation between SV and CTAB. These results were compared to those of a novel room temperature surface active ionic liquid, which was synthesized by the removal of inorganic counterions from a 1:1 mixture of CTAB and SV. In this new compound the drug now constitutes a building block of the carrier and, as such, has considerably different surfactant properties to its building blocks. In addition, enhanced solubility in a range of solvents, including simulated gastric fluid, was observed. The study provides valuable experimental evidence concerning the performance of drug based surfactant ionic liquids and how their chemical manipulation, without altering the architecture of the API, leads to control of surfactant behavior and physicochemical properties. In turn, this should feed through to improved and controlled drug release rates and delivery mechanisms, and the prevention of precipitation or formation of polymorphs typical of crystalline form APIs. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Spontaneous surface self-assembly in protein-surfactant mixtures: interactions between hydrophobin and ethoxylated polysorbate surfactants.

    Science.gov (United States)

    Tucker, Ian M; Petkov, Jordan T; Penfold, Jeffrey; Thomas, Robert K; Li, Peixun; Cox, Andrew R; Hedges, Nick; Webster, John R P

    2014-05-08

    The synergistic interactions between certain ethoxylated polysorbate nonionic surfactants and the protein hydrophobin result in spontaneous self-assembly at the air-water interface to form layered surface structures. The surface structures are characterized using neutron reflectivity. The formation of the layered surface structures is promoted by the hydrophobic interaction between the polysorbate alkyl chain and the hydrophobic patch on the surface of the globular hydrophobin and the interaction between the ethoxylated sorbitan headgroup and hydrophilic regions of the protein. The range of the ethoxylated polysorbate concentrations over which the surface ordering occurs is a maximum for the more hydrophobic surfactant polyoxyethylene(8) sorbitan monostearate. The structures at the air-water interface are accompanied by a profound change in the wetting properties of the solution on hydrophobic substrates. In the absence of the polysorbate surfactant, hydrophobin wets a hydrophobic surface, whereas the hydrophobin/ethoxylated polysorbate mixtures where multilayer formation occurs result in a significant dewetting of hydrophobic surfaces. The spontaneous surface self-assembly for hydrophobin/ethoxylated polysorbate surfactant mixtures and the changes in surface wetting properties provide a different insight into protein-surfactant interactions and potential for manipulating surface and interfacial properties and protein surface behavior.

  5. Elastic properties of surfactant monolayers at liquid-liquid interfaces: A molecular dynamics study

    DEFF Research Database (Denmark)

    Laradji, Mohamed; Mouritsen, Ole G.

    2000-01-01

    Using a simple molecular model based on the Lennard-Jones potential, we systematically study the elastic properties of liquid-liquid interfaces containing surfactant molecules by means of extensive and large-scale molecular dynamics simulations. The main elastic constants of the interface...... is further increased. Using a Gaussian theory on an interfacial Ginzburg-Landau model of surfactants, we find that the initial decrease of the bending rigidity is attributed to coupling between fluctuations of the surfactant orientation field to those in the interfacial height. (C) 2000 American Institute......, corresponding to the interfacial tension and the mean bending modulus are determined from the analyses of the long-wavelength behavior of the structure factor of the capillary waves. We found that the interfacial tension decreases with increasing surfactant interfacial coverage and/or surfactant chain length...

  6. Self-assembled systems of water soluble metal 8-hydroxyquinolates with surfactants and conjugated polyelectrolytes

    DEFF Research Database (Denmark)

    Burrows, Hugh D.; Costa, Telma; Luisa Ramos, M.

    2016-01-01

    We have studied the interaction of 8-hydroxyquinoline-5-sulfonate (8-HQS) with the metal ions Al(III) and Zn(II) in aqueous solution in the presence of tetraalkylammonium surfactants using UV/vis absorption, fluorescence, NMR spectroscopy and electrical conductivity measurements, complemented...... surfactants, leading to marked increases in fluorescence intensity. However, significant differences are seen in the behavior of the two metal ions. With aluminium, a stable [Al(8-QS)3]3- anion is formed, and interacts, predominantly through electrostatic interactions, with the surfactant, without disrupting...... the metal ion coordination sphere. In contrast, with Zn(II), there is a competition between the metal ion and surfactants in the interaction with 8-HQS, although the [Zn(8-QS)2(H2O)2]2- species is stable at appropriate pH and surfactant concentration. The studies are extended to systems with the conjugated...

  7. SCREENING METHODS FOR SELECTION OF SURFACTANT FORMULATIONS FOR IOR FROM FRACTURED CARBONATE RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    William A. Goddard III; Yongchun Tang; Patrick Shuler; Mario Blanco; Yongfu Wu; Seung Soon Jang

    2005-07-01

    This topical report presents details of the laboratory work performed to complete Task 1 of this project; developing rapid screening methods to assess surfactant performance for IOR (Improved Oil Recovery) from fractured carbonate reservoirs. The desired outcome is to identify surfactant formulations that increase the rate and amount of aqueous phase imbibition into oil-rich, oil-wet carbonate reservoir rock. Changing the wettability from oil-wet to water-wet is one key to enhancing this water-phase imbibition process that in turn recovers additional oil from the matrix portion of a carbonate reservoir. The common laboratory test to evaluate candidate surfactant formulations is to measure directly the aqueous imbibition rate and oil recovery from small outcrop or reservoir cores, but this procedure typically requires several weeks. Two methods are presented here for the rapid screening of candidate surfactant formulations for their potential IOR performance in carbonate reservoirs. One promising surfactant screening protocol is based on the ability of a surfactant solution to remove aged crude oil that coats a clear calcite crystal (Iceland Spar). Good surfactant candidate solutions remove the most oil the quickest from the chips, plus change the apparent contact angle of the remaining oil droplets on the surface that thereby indicate increased water-wetting. The other fast surfactant screening method is based on the flotation behavior of powdered calcite in water. In this test protocol, first the calcite power is pre-treated to make the surface oil-wet. The next step is to add the pre-treated powder to a test tube and add a candidate aqueous surfactant formulation; the greater the percentage of the calcite that now sinks to the bottom rather than floats, the more effective the surfactant is in changing the solids to become now preferentially water-wet. Results from the screening test generally are consistent with surfactant performance reported in the literature.

  8. Height, Relationship Satisfaction, Jealousy, and Mate Retention

    Directory of Open Access Journals (Sweden)

    Gayle Brewer

    2009-07-01

    Full Text Available Male height is associated with high mate value. In particular, tall men are perceived as more attractive, dominant and of a higher status than shorter rivals, resulting in a greater lifetime reproductive success. Female infidelity and relationship dissolution may therefore present a greater risk to short men. It was predicted that tall men would report greater relationship satisfaction and lower jealousy and mate retention behavior than short men. Ninety eight heterosexual men in a current romantic relationship completed a questionnaire. Both linear and quadratic relationships were found between male height and relationship satisfaction, cognitive and behavioral jealousy. Tall men reported greater relationship satisfaction and lower levels of cognitive or behavioral jealousy than short men. In addition, linear and quadratic relationships were found between male height and a number of mate retention behaviors. Tall and short men engaged in different mate retention behaviors. These findings are consistent with previous research conducted in this area detailing the greater attractiveness of tall men.

  9. A Comparative Study of the Effect of Surfactant and Temperature in Fluid Interfaces

    Science.gov (United States)

    Cortes-Estrada, Aldo H.; Ibarra-Bracamontes, Laura A.; Aguilar-Corona, Alicia; Viramontes-Gamboa, Gonzalo

    2016-11-01

    A fluid interface is the boundary region formed when two immiscible fluids come into contact. One of the most important properties of fluid interfaces is the interfacial tension. The interfacial tension between two fluids can be modified by the presence of surfactant. In addition, the temperature is a relevant factor that can also modify the interfacial properties. In this work the behavior of the interface formed by oil and water in the presence of surfactant at different temperatures is presented. Interfacial tension measurements were obtained by the Pendant Drop technique. Two types of surfactant were tested, Sodium Dodecyl Sulfate (SDS) as a hydrophilic surfactant, and Sorbitan Monooleate (Span 80) as a lipophilic surfactant. The range of variations in temperature was from 25 to 60 Celsius degree. Hexane or Dodecane was used as the oil phase. The main results showed that the lipophilic surfactant showed a greater efficiency with respect to the hydrophilic surfactant used. As the temperature increased in the range considered an exponential decay for the interfacial tension was observed. This decay was dominated by the surfactant concentration. This study was supported by the Mexican Council of Science and Technology (CONACyT) and by the Scientific Research Coordination of the University of Michoacan in Mexico.

  10. Fall 1982 Retention Study.

    Science.gov (United States)

    Peralta Community Coll. District, Oakland, CA. Office of Research, Planning and Development.

    In fall 1982, a study was conducted in the Peralta Community College District (PCCD) using withdrawal and grade distribution data to analyze student retention patterns. Successful retention rates were based on the percentage of students who received a passing grade, while total retention rates were based on the percentage of students who received…

  11. Fall 1984 Retention Study.

    Science.gov (United States)

    Peralta Community Coll. District, Oakland, CA. Office of Research, Planning and Development.

    A study was conducted of the retention patterns of students enrolled in the Peralta Community College District (PCCD) in fall 1984 using college reports on withdrawals and grade distributions. The study focused on successful retention (i.e., all students who received a passing grade) and on total retention (i.e., all students who received any…

  12. Experimental study on the effects of shear induced structure in a drag-reducing surfactant solution flow

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongxia; Wang, Dezhong; Chen, Hanping [Shanghai Jiao Tong University, School of Mechanical Engineering, Shanghai (China)

    2009-08-15

    In this paper, The drag reduction characteristics of surfactant solutions have been experimentally studied, as well as, the shear viscosities of turbulent drag-reducing surfactant solution have been measured as a function of concentration, shear rate and temperature by using AG-G2 (TA Instruments, New Castle, USA) rheometer. In comparison the rheological property with the macroscopic behavior of the solutions in turbulent channel flow, a deeper insight into the mechanisms of drag-reducing surfactant solution has been obtained. For no shear induced structure of surfactant solutions they just show features shear thinning, but the drag reduction is very significant phenomenon. Surfactant solution of the shear induced structure is not a surfactant fluid drag reduction of the necessary elements. (orig.)

  13. Transport, retention, and long-term release behavior of ZnO nanoparticle aggregates in saturated quartz sand: Role of solution pH and biofilm coating.

    Science.gov (United States)

    Han, Yosep; Hwang, Gukhwa; Kim, Donghyun; Bradford, Scott A; Lee, Byoungcheun; Eom, Igchun; Kim, Pil Je; Choi, Siyoung Q; Kim, Hyunjung

    2016-03-01

    The transport, retention, and long-term release of zinc oxide nanoparticle aggregates (denoted below as ZnO-NPs) were investigated in saturated, bare and biofilm (Pseudomonas putida) coated sand packed columns. Almost complete retention of ZnO-NPs occurred in bare and biofilm coated sand when the influent solution pH was 9 and the ionic strength (IS) was 0.1 or 10 mM NaCl, and the retention profiles were always hyper-exponential. Increasing the solution IS and biofilm coating produced enhanced retention of ZnO-NPs near the column inlet. The enhanced NPs retention at high IS was attributed to more favorable NP-silica and NP-NP interactions; this was consistent with the interaction energy calculations. Meanwhile, the greater NPs retention in the presence of biofilm was attributed to larger roughness heights which alter the mass transfer rate, the interaction energy profile, and lever arms associated with the torque balance; e.g., scanning electron and atomic force microscopy was used to determine roughness heights of 33.4 nm and 97.8 nm for bare sand and biofilm-coated sand, respectively. Interactions between NPs and extracellular polymeric substances may have also contributed to enhanced NP retention in biofilm-coated sand at low IS. The long-term release of retained ZnO-NPs was subsequently investigated by continuously injecting NP-free solution at pH 6, 9, or 10 and keeping the IS constant at 10 mM. The amount and rate of retained ZnO-NP removal was strongly dependent on the solution pH. Specifically, almost complete removal of retained ZnO-NPs was observed after 627 pore volumes when the solution pH was 6, whereas much less Zn was recovered when the eluting solution pH was buffered to pH = 9 and especially 10. This long-term removal was attributed to pH-dependent dissolution of retained ZnO-NPs because: (i) the solubility of ZnO-NPs increases with decreasing pH; and (ii) ZnO-NPs were not detected in the effluent. The presence of biofilm also decreased the

  14. Fungal growth on anion surfactant medium.

    Science.gov (United States)

    Hamada, Nobuo; Abe, Niichiro

    2009-12-01

    Before the present study, no fungi using anion surfactant as a nutrient had been identified, although some fungi were known to use nonion surfactant. Washing water collected from 63 washing machines was inoculated onto 0.1% LAS (Sodium dodecyl benzenesulfonate) anion surfactant media to identify fungi that can feed on anion-surfactant. Small dark colonies of fungi were found on several of the Petri-dishes from 12 days after inoculation. These were identified as Cladophialophora boppii and Exophiala spinifera using morphological features and rDNA data. A number of the isolates of C. boppii specifically were recognized as using anion surfactant as a nutrient. The growth characteristics of the two fungal species were examined on surfactant media of three kinds. Apart from anion surfactant, the fungi were also able to grow on nonion surfactant and on soap. The application of these fungi for environmental cleansing after detergent pollution is also discussed.

  15. Synthesis of carbohydrate-based surfactants

    Science.gov (United States)

    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.

  16. A Critical Look at Military Recruitment and Retention Policies

    Science.gov (United States)

    1985-03-01

    randomness in the attrition and reenlistment behavior of individual enlistees. The basis for these techniques is the retention function, which describes the...random) length of service of an individual enlistee. Policy analysis requires comparison of the aggresate effects of particular retention patterns...that might change enlistment and retentiOn behavior . The short-term effects of such changes critically depend on the initial condition; (force

  17. Surfactant Therapy of ALI and ARDS

    OpenAIRE

    Raghavendran, K; Willson, D; Notter, RH

    2011-01-01

    This article examines exogenous lung surfactant replacement therapy and its utility in mitigating clinical acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). Biophysical research has documented that lung surfactant dysfunction can be reversed or mitigated by increasing surfactant concentration, and multiple studies in animals with ALI/ARDS have shown that respiratory function and pulmonary mechanics in vivo can be improved by exogenous surfactant administration. Exoge...

  18. Cationic surfactants as the hydrolytic micellar catalysts

    OpenAIRE

    Janošcová, Petra

    2013-01-01

    Cationic surfactants as the hydrolytic micellar catalysts Petra Janošcová The effectiveness of hydrolytic cleavage of the pesticide fenitrothionin cationic surfactants micellar media has been tested. All used surfactants increased the rate of fenitrothionhydrolysis, which was the evidence of micellar catalysis. For some surfactants decreases has been evident at the highest rate of hydrolysis concentrations. It has been the result of a phenomenon called the effect of empty micelles. High hydro...

  19. 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

  20. Surfactant adsorption to soil components and soils

    NARCIS (Netherlands)

    Ishiguro, Munehide; Koopal, Luuk K.

    2016-01-01

    Soils are complex and widely varying mixtures of organic matter and inorganic materials; adsorption of surfactants to soils is therefore related to the soil composition. We first discuss the properties of surfactants, including the critical micelle concentration (CMC) and surfactant adsorption on

  1. EFFECTS OF NANOPARTICLES AND SURFACTANT CHARGE GROUPS ON THE PROPERTIES OF VES GEL

    Directory of Open Access Journals (Sweden)

    G. Chauhan

    Full Text Available Abstract Application of viscoelastic surfactant (VES fluids in hydraulic fracturing is still in the development stage, though shear thinning behavior and water solubility are the two important characteristics behind increasing interest in their use in fracturing jobs. Effects of ionic characteristics and the concentration of different surfactants on the rheological properties of VES fluid have been investigated in detail in the present study for a number of surfactant systems. Phase behavior of the system was studied and the gel region was identified. Effects of alkali on the viscosity, thermal stability, and miscibility (in water of the developed gel were also investigated. Dynamic rheological study was carried out to determine the storage modulus and loss modulus. This study shows that mixed anionic-anionic system gives improved rheology compared to single anionic and mixed anionic-zwitterionic surfactant systems.

  2. Surfactant-bound monolithic columns for CEC.

    Science.gov (United States)

    Gu, Congying; He, Jun; Jia, Jinping; Fang, Nenghu; Shamsi, Shahab A

    2009-11-01

    A novel anionic surfactant bound monolithic stationary phase based on 11-acrylaminoundecanoic acid is designed for CEC. The monolith possessing bonded undecanoyl groups (hydrophobic sites) and carboxyl groups (weak cationic ion-exchange sites) were evaluated as a mixed-mode stationary phase in CEC for the separation of neutral and polar solutes. Using a multivariate D-optimal design the composition of the polymerization mixture was modeled and optimized with five alkylbenzenes and seven alkyl phenyl ketones as test solutes. The D-optimal design indicates a strong dependence of electrochromatographic parameters on the concentration of 11-acrylaminoundecanoic acid monomer and porogen (water) in the polymerization mixture. A difference of 6, 8 and 13% RSD between the predicted and the experimental values in terms of efficiency, resolution and retention time, respectively, indeed confirmed that the proposed approach is practical. The physical (i.e. morphology, porosity and permeability) and chromatographic properties of the monolithic columns were thoroughly investigated. With the optimized monolithic column, high efficiency separation of N-methylcarbamates pesticides and positional isomers was successfully achieved. It appears that this type of mixed-mode monolith (containing both chargeable and hydrophobic sites) may have a great potential as a new generation of CEC stationary phase.

  3. 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.

  4. 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.

  5. Calcium-tolerant anionic surfactants

    NARCIS (Netherlands)

    Kooreman, Alexander

    1995-01-01

    One of the problems of applying anionic surfactants in, for example, laundry detergents is the precipitation of calcium salts. Much effort has been directed towards avoiding precipitation. There are at least three ways for tackling the problem. The first involves the use of a large quantity of

  6. Dipalmitoylphosphatidylcholine is not the major surfactant phospholipid species in all mammals.

    Science.gov (United States)

    Lang, Carol J; Postle, Anthony D; Orgeig, Sandra; Possmayer, Fred; Bernhard, Wolfgang; Panda, Amiya K; Jürgens, Klaus D; Milsom, William K; Nag, Kaushik; Daniels, Christopher B

    2005-11-01

    Pulmonary surfactant, a complex mixture of lipids and proteins, lowers the surface tension in terminal air spaces and is crucial for lung function. Within an animal species, surfactant composition can be influenced by development, disease, respiratory rate, and/or body temperature. Here, we analyzed the composition of surfactant in three heterothermic mammals (dunnart, bat, squirrel), displaying different torpor patterns, to determine: 1) whether increases in surfactant cholesterol (Chol) and phospholipid (PL) saturation occur during long-term torpor in squirrels, as in bats and dunnarts; 2) whether surfactant proteins change during torpor; and 3) whether PL molecular species (molsp) composition is altered. In addition, we analyzed the molsp composition of a further nine mammals (including placental/marsupial and hetero-/homeothermic contrasts) to determine whether phylogeny or thermal behavior determines molsp composition in mammals. We discovered that like bats and dunnarts, surfactant Chol increases during torpor in squirrels. However, changes in PL saturation during torpor may not be universal. Torpor was accompanied by a decrease in surfactant protein A in dunnarts and squirrels, but not in bats, whereas surfactant protein B did not change in any species. Phosphatidylcholine (PC)16:0/16:0 is highly variable between mammals and is not the major PL in the wombat, dunnart, shrew, or Tasmanian devil. An inverse relationship exists between PC16:0/16:0 and two of the major fluidizing components, PC16:0/16:1 and PC16:0/14:0. The PL molsp profile of an animal species is not determined by phylogeny or thermal behavior. We conclude that there is no single PL molsp composition that functions optimally in all mammals; rather, surfactant from each animal is unique and tailored to the biology of that animal.

  7. Effects of Surfactant on the Transport of Toxoplasma gondii in Saturated Sandy Porous Media: Experimental Tests and Modeling

    Science.gov (United States)

    Darnault, C. J. G.; Mutty, T.; L'Ollivier, C.; Dubey, J. P.; Aurélien, D.; Pullano, C. P.

    2017-12-01

    Understanding the transport of pathogens in the subsurface environment is essential for the risk assessment of groundwater contamination and the potential threat to human health. Currently, there is a lack of research in particular concerning the fate and transport of Toxoplasma gondii in porous media. The purpose of this research will be to characterize and model the transport and retention of Toxoplasma gondii in saturated silica-sand porous media in the presence of surfactant. Surfactants are chemicals commonly used as detergents and soaps, however they are able to impact flow properties in porous media and the interactions between surfaces, such as oocysts walls with sand grains. Therefore, we chose to characterize the changes that two surfactants have on the transport and fate of T. gondii. A total of 14 Column experiments were conducted including replicates as follows: 6 columns with an anionic-surfactant solution, 6 with a nonionic-surfactant solution, and 2 columns without surfactant to act as controls. All of the columns contained fine sand as the dominant grain size and each was run with a specified saturated flow rate in order to analyze the change with surfactant and disregard change as a result of a variation in the pore velocity. We chose to determine the retention and flow using the classic clean-bed colloid filtration model, and implemented sources for both adsorption and desorption of the particles which is known to happen on other biocolloids including oocysts. We implemented both Linear alkylbenzene sulphonic acid and Alkylphenol ethoxylate as our surfactants since they are the anionic and nonionic surfactants most commonly found in wastewater. Three different Critical Micelle Concentrations (CMC's) were run through the columns prior to the T. gondii oocysts injection followed by sequential injection of surfactant only and then deionized water only. The study compares the breakthrough of T. gondii with surfactant, without surfactant, as well as a

  8. Effect of surfactant concentration on the evaporation of droplets on cotton (Gossypium hirsutum L.) leaves.

    Science.gov (United States)

    Zhou, Zhaolu; Cao, Chong; Cao, Lidong; Zheng, Li; Xu, Jun; Li, Fengmin; Huang, Qiliang

    2018-04-05

    The evaporation kinetics of pesticide droplets deposited on a leaf surface can affect their application efficiency. Evaporation of droplets on the hydrophobic leaves has received considerable attention, but little is known about hydrophilic leaf surfaces. In this study, the effect of surfactant concentration on the evaporation of droplets deposited on cotton leaves was investigated. The evaporation time is roughly decreased for concentrations ranging from 0% to 0.01% and increased from 0.01% to 0.10%. Contrary to the widely held belief that pesticide retention on target crops can rapidly be formed only with surfactant concentrations exceeding the CMC (critical micelle concentration), this study demonstrates that, on hydrophilic cotton leaves, fast evaporation of the droplet at surfactant concentrations of 0.01% (CMC) can reduce the volume quickly, lower the loss point and enhance pesticide retention. In addition, the evolution of droplet volume, height and contact angle on the cotton leaf surface were measured to confirm this conclusion. The result presented herein can be used to guide the use of surfactants and pesticides in agriculture. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. 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.

  10. Surfactant-based critical phenomena in microgravity

    Science.gov (United States)

    Kaler, Eric W.; Paulaitis, Michael E.

    1994-01-01

    The objective of this research project is to characterize by experiment and theoretically both the kinetics of phase separation and the metastable structures produced during phase separation in a microgravity environment. The particular systems we are currently studying are mixtures of water, nonionic surfactants, and compressible supercritical fluids at temperatures and pressures where the coexisting liquid phases have equal densities (isopycnic phases). In this report, we describe experiments to locate equilibrium isopycnic phases and to determine the 'local' phase behavior and critical phenomena at nearby conditions of temperature, pressure, and composition. In addition, we report the results of preliminary small angle neutron scattering (SANS) experiments to characterize microstructures that exist in these mixtures at different fluid densities.

  11. Dispersion and rheology of surfactant-mediated silver nanoparticle suspensions

    Science.gov (United States)

    Chen, Chun-Nan; Huang, Chih-Ta; Tseng, Wenjea J.; Wei, Ming-Hsiung

    2010-11-01

    Polycrystalline silver (Ag) nanoparticles were dispersed in solvent mixtures consisting of 2-butoxyethyl acetate (BCA) and diethylene glycol monoethyl ether acetate (CA) in a BCA:CA weight ratio of 5:1. Three commercially available polymeric surfactants were used, and the gravitational sedimentation, agglomerate-size distribution, isothermal adsorption, and rheological behavior of the nanoparticle suspensions were examined. One of the surfactants (hereafter termed 9250) was found effective in stabilizing the Ag nanoparticle suspensions. Both the adsorption isotherm and the Fourier transform infrared spectroscopy revealed the preferential adsorption of the 9250 surfactant molecules on the nanoparticle surface, forming a Langmuir-type monolayer adsorption in the given solvents so that a steric stabilization was rendered. An optimal surfactant concentration of 5 wt.% (in terms of the solids weight) was determined experimentally. In addition, the Ag suspensions with a broad range of solids concentration (ϕ = 1-16 vol.%) showed a shear-thinning flow character over a shear-rate range from 1 to 4000 s-1, revealing that an attractive interparticle interaction was operative. Relative viscosity (ηr) of the nanoparticle suspensions deviated from the linearity when ϕ was greater than ˜10 vol.%; at which, the attractive potential began to dominate the interparticle interactions. This ηr-ϕ dependence was compared with various existing models and the (viscosity) predictive capability of the models was discussed.

  12. Partitioning of hydrophobic pesticides within a soil-water-anionic surfactant system.

    Science.gov (United States)

    Wang, Peng; Keller, Arturo A

    2009-02-01

    Surfactants can be added to pesticide-contaminated soils to enhance the treatment efficiency of soil washing. Our results showed that pesticide (atrazine and diuron) partitioning and desorbability within a soil-water-anionic surfactant system is soil particle-size dependent and is significantly influenced by the presence of anionic surfactant. Anionic surfactant (linear alkylbenzene sulphonate, LAS) sorption was influenced by its complexation with both the soluble and exchangeable divalent cations in soils (e.g. Ca2+, Mg2+). In this study, we propose a new concept: soil system hardness which defines the total amount of soluble and exchangeable divalent cations associated with a soil. Our results showed that anionic surfactant works better with soils having lower soil system hardness. It was also found that the hydrophobic organic compounds (HOCs) sorbed onto the LAS-divalent cation precipitate, resulting in a significant decrease in the aqueous concentration of HOC. Our results showed that the effect of exchangeable cations and sorption of HOC onto the surfactant precipitates needs to be considered to accurately predict HOC behavior within soil-water-anionic surfactant systems.

  13. LOWER COST METHODS FOR IMPROVED OIL RECOVERY (IOR) VIA SURFACTANT FLOODING

    Energy Technology Data Exchange (ETDEWEB)

    William A. Goddard III; Yongchun Tang; Patrick Shuler; Mario Blanco; Seung Soon Jang; Shiang-Tai Lin; Prabal Maiti; Yongfu Wu; Stefan Iglauer; Xiaohang Zhang

    2004-09-01

    This report provides a summary of the work performed in this 3-year project sponsored by DOE. The overall objective of this project is to identify new, potentially more cost-effective surfactant formulations for improved oil recovery (IOR). The general approach is to use an integrated experimental and computational chemistry effort to improve our understanding of the link between surfactant structure and performance, and from this knowledge, develop improved IOR surfactant formulations. Accomplishments for the project include: (1) completion of a literature review to assemble current and new surfactant IOR ideas, (2) Development of new atomistic-level MD (molecular dynamic) modeling methodologies to calculate IFT (interfacial tension) rigorously from first principles, (3) exploration of less computationally intensive mesoscale methods to estimate IFT, Quantitative Structure Property Relationship (QSPR), and cohesive energy density (CED) calculations, (4) experiments to screen many surfactant structures for desirable low IFT and solid adsorption behavior, and (5) further experimental characterization of the more promising new candidate formulations (based on alkyl polyglycosides (APG) and alkyl propoxy sulfate surfactants). Important findings from this project include: (1) the IFT between two pure substances may be calculated quantitatively from fundamental principles using Molecular Dynamics, the same approach can provide qualitative results for ternary systems containing a surfactant, (2) low concentrations of alkyl polyglycoside surfactants have potential for IOR (Improved Oil Recovery) applications from a technical standpoint (if formulated properly with a cosurfactant, they can create a low IFT at low concentration) and also are viable economically as they are available commercially, and (3) the alkylpropoxy sulfate surfactants have promising IFT performance also, plus these surfactants can have high optimal salinity and so may be attractive for use in higher

  14. Stabilization of diketo tautomer of curcumin by premicellar anionic surfactants: UV-Visible, fluorescence, tensiometric and TD-DFT evidences.

    Science.gov (United States)

    Dutta, Anisha; Boruah, Bornali; Manna, Arun K; Gohain, Biren; Saikia, Palash M; Dutta, Robin K

    2013-03-01

    A newly observed UV band of aqueous curcumin, a biologically important molecule, in presence of anionic surfactants, viz., sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and sodium dodecylsulfonate (SDSN) in buffered aqueous solutions has been studied experimentally and theoretically. The 425 nm absorption band of curcumin disappears and a new UV-band is observed at 355 nm on addition of the surfactants in the submicellar concentration range which is reversed as the surfactant concentration approaches the critical micelle concentration (CMC). The observed spectral absorption, fluorescence intensity and surface tension behavior, under optimal experimental conditions of submicellar concentration ranges of the surfactants in the pH range of 2.00-7.00, indicate that the new band is due to the β-diketo tautomer of curcumin stabilized by interactions between curcumin and the anionic surfactants. The stabilization of the diketo tautomer by submicellar anionic surfactants described here as well as by submicellar cationic surfactant, reported recently, is unique as this is the only such behavior observed in presence of submicellar surfactants of both charge types. The experimental results are in good agreement with the theoretical calculations using ab initio density functional theory combined with time dependent density functional theory (TD-DFT) calculations. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

    Science.gov (United States)

    Miranda, Paulo Barbeitas

    Surfactants are widely used to modify physical and chemical properties of interfaces. They play an important role in many technological problems. Surfactant monolayers are also of great scientific interest because they are two-dimensional systems that may exhibit a very rich phase transition behavior and can also be considered as a model system for biological interfaces. In this Thesis, we use a second-order nonlinear optical technique (Sum-Frequency Generation - SFG) to obtain vibrational spectra of surfactant monolayers at liquid/vapor and solid/liquid interfaces. The technique has several advantages: it is intrinsically surface-specific, can be applied to buried interfaces, has submonolayer sensitivity and is remarkably sensitive to the conformational order of surfactant monolayers. The first part of the Thesis is concerned with surfactant monolayers at the air/water interface (Langmuir films). Surface crystallization of an alcohol Langmuir film and of liquid alkanes are studied and their phase transition behaviors are found to be of different nature, although driven by similar intermolecular interactions. The effect of crystalline order of Langmuir monolayers on the interfacial water structure is also investigated. It is shown that water forms a well-ordered hydrogen-bonded network underneath an alcohol monolayer, in contrast to a fatty acid monolayer which induces a more disordered structure. In the latter case, ionization of the monolayer becomes more significant with increase of the water pH value, leading to an electric-field-induced ordering of interfacial water molecules. We also show that the orientation and conformation of fairly complicated molecules in a Langmuir monolayer can be completely mapped out using a combination of SFG and second harmonic generation (SHG). For a quantitative analysis of molecular orientation at an interface, local-field corrections must be included. The second part is a study of self-assembled surfactant monolayers at the

  16. 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.

  17. A conservative SPH method for surfactant dynamics

    Science.gov (United States)

    Adami, S.; Hu, X. Y.; Adams, N. A.

    2010-03-01

    In this paper, a Lagrangian particle method is proposed for the simulation of multiphase flows with surfactant. The model is based on the multiphase smoothed particle hydrodynamics (SPH) framework of Hu and Adams (2006) [1]. Surface-active agents (surfactants) are incorporated into our method by a scalar quantity describing the local concentration of molecules in the bulk phase and on the interface. The surfactant dynamics are written in conservative form, thus global mass of surfactant is conserved exactly. The transport model of the surfactant accounts for advection and diffusion. Within our method, we can simulate insoluble surfactant on an arbitrary interface geometry as well as interfacial transport such as adsorption or desorption. The flow-field dynamics and the surfactant dynamics are coupled through a constitutive equation, which relates the local surfactant concentration to the local surface-tension coefficient. Hence, the surface-tension model includes capillary and Marangoni-forces. The present numerical method is validated by comparison with analytic solutions for diffusion and for surfactant dynamics. More complex simulations of an oscillating bubble, the bubble deformation in a shear flow, and of a Marangoni-force driven bubble show the capabilities of our method to simulate interfacial flows with surfactants.

  18. Self-consistent field modeling of adsorption from polymer/surfactant mixtures.

    Science.gov (United States)

    Postmus, Bart R; Leermakers, Frans A M; Cohen Stuart, Martien A

    2008-06-01

    We report on the development of a self-consistent field model that describes the competitive adsorption of nonionic alkyl-(ethylene oxide) surfactants and nonionic polymer poly(ethylene oxide) (PEO) from aqueous solutions onto silica. The model explicitly describes the response to the pH and the ionic strength. On an inorganic oxide surface such as silica, the dissociation of the surface depends on the pH. However, salt ions can screen charges on the surface, and hence, the number of dissociated groups also depends on the ionic strength. Furthermore, the solvent quality for the EO groups is a function of the ionic strength. Using our model, we can compute bulk parameters such as the average size of the polymer coil and the surfactant CMC. We can make predictions on the adsorption behavior of either polymers or surfactants, and we have made adsorption isotherms, i.e., calculated the relationship between the surface excess and its corresponding bulk concentration. When we add both polymer and surfactant to our mixture, we can find a surfactant concentration (or, more precisely, a surfactant chemical potential) below which only the polymer will adsorb and above which only the surfactant will adsorb. The corresponding surfactant concentration is called the CSAC. In a first-order approximation, the surfactant chemical potential has the CMC as its upper bound. We can find conditions for which CMC model is to understand the experimental data from one of our previous articles. We managed to explain most, but unfortunately not all, of the experimental trends. At the end of the article we discuss the possibilities for improving the model.

  19. Effect of ionic surfactant on the self-assembly of triblock copolymer

    Science.gov (United States)

    Ray, D.; Kohlbrecher, J.; Aswal, V. K.

    2017-05-01

    The effect of anionic surfactant sodium dodecyl sulfate (SDS) on the self-assembly of PEO-PPO-PEO triblock copolymer in aqueous solution has been studied using small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactant, and at varying temperatures between 20 to 80°C. Micelles of pure ionic surfactants show little change in their sizes with increasing temperature, whereas structures of the non-ionic micelles increase significantly (sphere-to-rod transition for some block copolymers). Contrast variation SANS measurement suggests addition of SDS to aqueous copolymer solutions leads to the formation of mixed micelles. Interestingly, the self-assembly of block copolymer is found to get completely arrested by the ionic surfactant in the mixed micelles which gives a control over the block copolymer phase behavior.

  20. Rheologycal properties of sodium carboxymethylcellulose in the presence of electrolyte and mixed micelle of surfactants

    Directory of Open Access Journals (Sweden)

    Sovilj Verica J.

    2003-01-01

    Full Text Available One of the most significant aspects of polymer-surfactant interaction, from the practical point of view, is that of rheology control and viscosity enhancement. In the oppositely charged polyelectrolyte-surfactant system strong ionic interaction often leads to precipitation of the formed complex yielding serious problems. In this paper the interaction between anionic polyelectrolyte - sodium carboxymethylcellulose (NaCMC and cationic surfactant - cethyltrimethylammonium bromide (CTMAB has been investigated by rheological measurements. Addition of electrolyte NaBr and nonionic surfactant - Tween 80 reduced the binding strength, prevented the precipitation of the complex and increased the viscosity of the system. It was found that rheological properties are strong influenced by NaCMC-CTMAB interaction and the system exhibits either pseudoplastic or thixotropic or rheopectic behavior according to the intensity of interaction.

  1. Competitive adsorption of monoclonal antibodies and nonionic surfactants at solid hydrophobic surfaces

    DEFF Research Database (Denmark)

    Kapp, Sebastian J; Larsson, Iben; van de Weert, Marco

    2015-01-01

    , such as infusion bags and i.v. lines. Total internal reflection fluorescence and quartz crystal microbalance with dissipation monitoring were used to follow and quantify this. Furthermore, the influence of the nonionic surfactant polysorbate 80 (PS80) on the adsorption process of these two antibodies...... was investigated. Despite belonging to two different IgG subclasses, both antibodies displayed comparable adsorption behavior. Both antibodies readily adsorbed in the absence of PS80, whereas adsorption was reduced in the presence of 30 mg/L surfactant. The sequence of exposure of the surfactant and protein...... to the surface was found to have a major influence on the extent of protein adsorption. Although only a fraction of adsorbed protein could be removed by rinsing with 30 mg/L surfactant solution, adsorption was entirely prevented when surfaces were pre-exposed to PS80. © 2014 Wiley Periodicals, Inc...

  2. Synthesis and bio-physicochemical properties of amide-functionalized N-methylpiperazinium surfactants.

    Science.gov (United States)

    Chauhan, Vinay; Singh, Sukhprit; Mishra, Rachana; Kaur, Gurcharan

    2014-12-15

    Four new amide functionalized N-methylpiperazinium amphiphiles having tetradecyl, hexadecyl alkyl chain lengths and counterions; chloride or bromide have been synthesized and characterized by various spectroscopic techniques. These new surfactants have been investigated in detail for their self-assembling behavior by surface tension, conductivity and fluorescence measurements. The thermodynamic parameters of these surfactants indicate that micellization is exothermic and entropy-driven. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) experiments have been performed to insight the aggregate size of these cationics. Thermal degradation of these new surfactants has also been evaluated by thermal gravimetric analysis (TGA). These new surfactants form stable complexes with DNA as acknowledged by agarose gel electrophoresis, ethidium bromide exclusion and zeta potential measurements. They have also been found to have low cytotoxicity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on the C6 glioma cell line. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Surfactants in tribology, v.3

    CERN Document Server

    Biresaw, Girma

    2013-01-01

    The manufacture and use of almost every consumer and industrial product rely on application of advanced knowledge in surface science and tribology. These two disciplines are of critical importance in major economic sectors, such as mining, agriculture, manufacturing (including metals, plastics, wood, computers, MEMS, NEMS, appliances), construction, transportation, and medical instruments, transplants, and diagnostic devices. An up-to-date reference with contributions by experts in surface science and tribology, Surfactants in Tribology, Volume 3 discusses some of the underlying tribological a

  4. 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.

  5. Cationic versus anionic surfactant in tuning the structure and interaction of nanoparticle, protein, and surfactant complexes.

    Science.gov (United States)

    Mehan, Sumit; Aswal, Vinod K; Kohlbrecher, Joachim

    2014-08-26

    The structure and interaction in complexes of anionic Ludox HS40 silica nanoparticle, anionic bovine serum albumin (BSA) protein, and cationic dodecyl trimethylammonium bromide (DTAB) surfactant have been studied using small-angle neutron scattering (SANS). The results are compared with similar complexes having anionic sodium dodecyl sulfate (SDS) surfactant (Mehan, S; Chinchalikar, A. J.; Kumar, S.; Aswal, V. K.; Schweins, R. Langmuir 2013, 29, 11290). In both cases (DTAB and SDS), the structure in nanoparticle-protein-surfactant complexes is predominantly determined by the interactions of the individual two-component systems. The nanoparticle-surfactant (mediated through protein-surfactant complex) and protein-surfactant interactions for DTAB, but nanoparticle-protein (mediated through protein-surfactant complex) and protein-surfactant interactions for SDS, are found to be responsible for the resultant structure of nanoparticle-protein-surfactant complexes. Irrespective of the charge on the surfactant, the cooperative binding of surfactant with protein leads to micellelike clusters of surfactant formed along the unfolded protein chain. The adsorption of these protein-surfactant complexes for DTAB on oppositely charged nanoparticles gives rise to the protein-surfactant complex-mediated aggregation of nanoparticles (similar to that of DTAB surfactant). It is unlike that of depletion-induced aggregation of nanoparticles with nonadsorption of protein-surfactant complexes for SDS in similarly charged nanoparticle systems (similar to that of protein alone). The modifications in nanoparticle aggregation as well as unfolding of protein in these systems as compared to the corresponding two-component systems have also been examined by selectively contrast matching the constituents.

  6. Surfactant-enhanced cellulose nanocrystal Pickering emulsions.

    Science.gov (United States)

    Hu, Zhen; Ballinger, Sarah; Pelton, Robert; Cranston, Emily D

    2015-02-01

    The effect of surfactants on the properties of Pickering emulsions stabilized by cellulose nanocrystals (CNCs) was investigated. Electrophoretic mobility, interfacial tension, confocal microscopy and three-phase contact angle measurements were used to elucidate the interactions between anionic CNCs and cationic alkyl ammonium surfactants didecyldimethylammonium bromide (DMAB) and cetyltrimethylammonium bromide (CTAB). Both surfactants were found to adsorb onto CNCs with concentration-dependent morphology. At low concentrations, individual surfactant molecules adsorbed with alkyl tails pointing outward leading to hydrophobic CNCs. At higher concentrations, above the surfactant's apparent critical micelle concentration, surfactant aggregate morphologies on CNCs were inferred and the hydrophobicity of CNCs decreased. DMAB, which has two alkyl tails, rendered the CNCs more hydrophobic than CTAB which has only a single alkyl tail, at all surfactant concentrations. The change in CNC wettability from surfactant adsorption was directly linked to emulsion properties; adding surfactant increased the emulsion stability, decreased the droplet size, and controlled the internal phase of CNC Pickering emulsions. More specifically, a double transitional phase inversion, from oil-in-water to water-in-oil and back to oil-in-water, was observed for emulsions with CNCs and increasing amounts of DMAB (the more hydrophobic surfactant). With CNCs and CTAB, no phase inversion was induced. This work represents the first report of CNC Pickering emulsions with surfactants as well as the first CNC Pickering emulsions that can be phase inverted. The ability to surface modify CNCs in situ and tailor emulsions by adding surfactants may extend the potential of CNCs to new liquid formulations and extruded/spray-dried materials. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Interactions between surfactants and hydrolytic enzymes.

    Science.gov (United States)

    Holmberg, Krister

    2017-12-05

    Hydrolytic enzymes are combined with surfactants in many types of formulations, for instance detergents and personal care products. If the surfactant interacts with the enzyme there may be conformational changes that eventually lead to loss of the enzymatic activity. From a practical point of view it is important to understand the nature and magnitude of these interactions. After an introduction of the topic the review briefly discusses enzyme catalyzed reactions where surfactants are substrates for the enzyme. The rest of the review relates to associations between surfactants and hydrolytic enzymes without the surfactant being a substrate in the reaction. A discussion about general principles for such interactions is followed by a survey of the relevant literature related to four important types of hydrolytic enzymes: lipases, proteases, amylases and cellulases. It is shown in the review that the effect exerted by the surfactant differs between the different types of enzymes; it is therefore difficult to make general statements about which surfactants are most detrimental to the activity of hydrolytic enzymes. However, as a general rule nonionic surfactants can be regarded as more benign to an enzyme than anionic and cationic surfactants. This difference can be ascribed to the difference in binding mode. Whereas a nonionic surfactant only binds to the enzyme through hydrophobic interactions, an ionic surfactant can bind by a combination of electrostatic attraction and hydrophobic interaction. This latter type of binding can be strong and lead to conformational changes already at very low surfactant concentration, often far below its critical micelle concentration. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. 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

  9. Flavonoid-surfactant interactions: A detailed physicochemical study

    Science.gov (United States)

    Singh, Onkar; Kaur, Rajwinder; Mahajan, Rakesh Kumar

    2017-01-01

    The aim of this article is to study the interactions between flavonoids and surfactants with attention of finding the probable location of flavonoids in micellar media that can be used for controlling their antioxidant behavior. In present study, the micellar and interfacial behavior of twin tailed anionic surfactants viz. sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP) in the presence of two flavonoids, namely quercetin (QUE) and kaempferol (KFL) have been studied by surface tension measurements. UV-visible, fluorescence and differential pulse voltammetric (DPV) measurements have been employed to predict the probable location of flavonoids (QUE/KFL) within surfactant (AOT/NaDEHP) aggregates. Dynamic light scattering (DLS) measurements further confirmed the solubilization of QUE/KFL in AOT/NaDEHP aggregates deduced from increased hydrodynamic diameter (Dh) of aggregates in the presence of flavonoids. Both radical scavenging activity (RSA) and degradation rate constant (k) of flavonoids are found to be higher in NaDEHP micelles as compared to AOT micelles.

  10. Impact of model perfumes on surfactant and mixed surfactant self-assembly.

    Science.gov (United States)

    Penfold, J; Tucker, I; Green, A; Grainger, D; Jones, C; Ford, G; Roberts, C; Hubbard, J; Petkov, J; Thomas, R K; Grillo, I

    2008-11-04

    The impact of some model perfumes on surfactant self-assembly has been investigated, using small-angle neutron scattering. A range of different model perfumes, with differing degrees of hydrophilicity/hydrophobicity, have been explored, and in order of increasing hydrophobicity include phenyl ethanol (PE), rose oxide (RO), limonene (LM), linalool (LL), and dihydrogen mercenol (DHM). The effect of their solubilization on the nonionic surfactant micelles of dodecaethylene monododecyl ether (C12EO12) and on the mixed surfactant aggregates of C12EO12 and the cationic dialkyl chain surfactant dihexadecyl dimethyl ammonium bromide (DHDAB) has been quantified. For PE and LL the effect of their solubilization on the micelle, mixed micelle/lamellar and lamellar regimes of the C12EO12/DHDAB mixtures, has also been determined. For the C12EO12 and mixed DHDAB/C12EO12 micelles PE is solubilized predominantly at the hydrophilic/hydrophobic interface, whereas the more hydrophobic perfumes, from RO to DHM, are solubilized predominantly in the hydrophobic core of the micelles. For the C12EO12 micelles, with increasing perfume concentration, the more hydrophobic perfumes (RO to DHM) promote micellar growth. Relatively modest growth is observed for RO and LM, whereas substantial growth is observed for LL and DHM. In contrast, for the addition of PE the C12EO12 micelles remain as relatively small globular micelles, with no significant growth. For the C12EO12/DHDAB mixed micelles, the pattern of behavior with the addition of perfume is broadly similar, except that the micellar growth with increasing perfume concentration for the more hydrophobic perfumes is less pronounced. In the Lbeta (Lv) region of the DHDAB-rich C12EO12/DHDAB phase diagram, the addition of PE results in a less structured (less rigid) lamellar phase, and ultimately a shift toward a structure more consistent with a sponge or bicontinuous phase. In the mixed L1/Lbeta region of the phase diagram PE induces a slight

  11. 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

  12. 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.

  13. Remediation using trace element humate surfactant

    Science.gov (United States)

    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.

  14. Urinary retention in women.

    Science.gov (United States)

    Juma, Saad

    2014-07-01

    This review is a summary of the most pertinent published studies in the literature in the last 18 months that address cause, diagnosis, and management of urinary retention in women. Symptoms, uroflow, and pressure-flow studies have a low predictive value for and do not correlate with elevated postvoid residual urine (PVR). Anterior and posterior colporrhaphy do not cause de-novo bladder outlet obstruction in the majority of patients with elevated PVR, and the cause of elevated PVR may be other factors such as pain or anxiety causing abnormal relaxation of the pelvic floor and contributing to voiding difficulty. The risk of urinary retention in a future pregnancy after mid-urethral sling (MUS) is small. The risk of urinary tract infection and urinary retention after chemodenervation of the bladder with onabotulinumtoxin-A (100 IU) in patients with non-neurogenic urge incontinence is 33 and 5%, respectively. There is a lack of consensus among experts on the timing of sling takedown in the management of acute urinary retention following MUS procedures. There has been a significant progress in the understanding of the causation of urinary retention. Important areas that need further research (basic and clinical) are post-MUS and pelvic organ prolapse repair urinary retention and obstruction, and urinary retention owing to detrusor underactivity.

  15. Physicochemical, morphological and cellular uptake properties of lutein nanodispersions prepared by using surfactants with different stabilizing mechanisms.

    Science.gov (United States)

    Tan, Tai Boon; Chu, Wern Cui; Yussof, Nor Shariffa; Abas, Faridah; Mirhosseini, Hamed; Cheah, Yoke Kqueen; Nehdi, Imededdine Arbi; Tan, Chin Ping

    2016-04-01

    In this study, we prepared a series of lutein nanodispersions via the solvent displacement method, by using surfactants with different stabilizing mechanisms. The surfactants used include Tween 80 (steric stabilization), sodium dodecyl sulfate (SDS; electrostatic stabilization), sodium caseinate (electrosteric stabilization) and SDS-Tween 80 (electrostatic-steric stabilization). We then characterized the resulting lutein nanodispersions in terms of their particle size, particle size distribution, zeta potential, lutein content, flow behavior, apparent viscosity, transmittance, color, morphological properties and their effects on cell viability and cellular uptake. The type of surfactant used significantly (p lutein content) remained unaffected. Transmission electron microscopy (TEM) images obtained from this study demonstrated that the solvent displacement method was capable of producing lutein nanodispersions containing spherical particles with sizes ranging from 66.20-125.25 nm, depending on the type of surfactant used. SDS and SDS-Tween 80 surfactants negatively affected the viability of the HT-29 cells used in this study. Thus, for the cellular uptake determination, only Tween 80 and sodium caseinate surfactants were used. The cellular uptake of the lutein nanodispersion stabilized by sodium caseinate was higher than that which was stabilized by Tween 80. All things considered, the type of surfactant with different stabilizing mechanisms did produce lutein nanodispersions with different characteristics. These findings would aid in future selection of surfactants in order to produce nanodispersions with desirable properties.

  16. Activity coefficients and free energies of nonionic mixed surfactant solutions from vapor-pressure and freezing-point osmometry.

    Science.gov (United States)

    MacNeil, Jennifer A; Ray, Gargi Basu; Leaist, Derek G

    2011-05-19

    The thermodynamic properties of mixed surfactant solutions are widely investigated, prompted by numerous practical applications of these systems and by interest in molecular association and self-organization. General techniques for measuring thermodynamic activities, such as isopiestic equilibration, are well-established for multicomponent solutions. Surprisingly, these techniques have not yet been applied to mixed surfactant solutions, despite the importance of the free energy for micelle stability. In this study, equations are developed for the osmotic coefficients of solutions of nonionic surfactant A + nonionic surfactant B. A mass-action model is used, with virial equations for the activity coefficients of the micelles and free surfactant monomer species. The equations are fitted to osmotic coefficients of aqueous decylsulfobetaine + dodecylsulfobetaine solutions measured by vapor-pressure and freezing-point osmometry. Equilibrium constants for mixed-micelle formation are calculated from the free monomer concentrations at the critical micelle concentrations. The derived activity coefficients of the micelles and free monomers indicate large departures from ideal solution behavior, even for dilute solutions of the surfactants. Stoichiometric activity coefficients of the total surfactant components are evaluated by Gibbs-Duhem integration of the osmotic coefficients. Relatively simple colligative property measurements hold considerable promise for free energy studies of multicomponent surfactant solutions. © 2011 American Chemical Society

  17. Hemolysis by surfactants--A review.

    Science.gov (United States)

    Manaargadoo-Catin, Magalie; Ali-Cherif, Anaïs; Pougnas, Jean-Luc; Perrin, Catherine

    2016-02-01

    An overview of the use of surfactants for erythrocyte lysis and their cell membrane action mechanisms is given. Erythrocyte membrane characteristics and its association with the cell cytoskeleton are presented in order to complete understanding of the erythrocyte membrane distortion. Cell homeostasis disturbances caused by surfactants might induce changes starting from shape modification to cell lysis. Two main mechanisms are hypothesized in literature which are osmotic lysis and lysis by solubilization even if the boundary between them is not clearly defined. Another specific mechanism based on the formation of membrane pores is suggested in the particular case of saponins. The lytic potency of a surfactant is related to its affinity for the membrane and the modification of the lipid membrane curvature. This is to be related to the surfactant shape defined by its hydrophobic and hydrophilic moieties but also by experimental conditions. As a consequence, prediction of the hemolytic potency of a given surfactant is challenging. Several studies are focused on the relation between surfactant erythrolytic potency and their physico-chemical parameters such as the critical micellar concentration (CMC), the hydrophile-lipophile balance (HLB), the surfactant membrane/water partition coefficient (K) or the packing parameter (P). The CMC is one of the most important factors considered even if a lytic activity cut-off effect points out that the only consideration of CMC not enough predictive. The relation K.CMC must be considered in addition to the CMC to predict the surfactant lytic capacity within the same family of non ionic surfactant. Those surfactant structure/lytic activity studies demonstrate the requirement to take into account a combination of physico-chemical parameters to understand and foresee surfactant lytic potency. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. [Chronic monstrous urine retention].

    Science.gov (United States)

    Thomsen, Frederik Gustav; Holm, Mette Lind

    2015-01-26

    A 75-year-old male was diagnosed with renal mass at a computed tomography during an examination for extended abdominal girth. A large mesenterical cyst was also detected. The patient had infrequent voiding, which he had trained over many years as a taxi driver. A basic physical examination led to suspect urinary retention. His creatinine level was normal and he had no hydronephrosis. A renography showed equal function, but prolonged bilateral outflow. The volume extracted by urethral catheter passed 15 l. Absence of hydronephrosis and normal S-creatinine level has not been described in chronic urinary retention of this extent. Hydronephrosis is seen, but in much smaller volume of retention. Infrequent voiding is easily diagnosed. Urinary retention should be suspected when finding median cystic processes.

  19. Liquid Effluent Retention Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Liquid Effluent Retention Facility (LERF) is located in the central part of the Hanford Site. LERF is permitted by the State of Washington and has three liquid...

  20. Drug Retention Times

    Energy Technology Data Exchange (ETDEWEB)

    Center for Human Reliability Studies

    2007-05-01

    The purpose of this monograph is to provide information on drug retention times in the human body. The information provided is based on plausible illegal drug use activities that might be engaged in by a recreational drug user.

  1. Foraging behavior of the mangrove sesarmid crab Neosarmatium trispinosum enhances food intake and nutrient retention in a low-quality food environment

    Science.gov (United States)

    Harada, Yota; Lee, S. Y.

    2016-06-01

    The large sesarmid crab Neosarmatium trispinosum has been reported to actively collect freshly fallen mangrove leaves and store them in its burrow where they are assumed to age prior to consumption. This leaf-catching behavior was hypothesized to improve the palatability and nutritional quality of leaves through leaching of feeding deterrent and microbial enrichment during storage. Earlier studies also hypothesized that N. trispinosum feeds on sediment or animal material to meet their N needs. A series of experiments was carried out to investigate the foraging behavior of N. trispinosum against these hypotheses. Study of foraging behavior using remotely operated cameras indicated that this crab spends the far majority of time (97.5 ± 2.5%, SD) underground and only a small percentage of time outside its burrow foraging (2.2 ± 2.3%). Collection of fresh mangrove litter was swift but no record of predation was evident over 31 h of video records. A field leaf tethering experiment showed that this crab started to consume the leaves immediately after collection rather than storing whole leaves, refuting the leaf-aging hypothesis. N. trispinosum also showed a preference for senescent yellow leaves over decaying brown leaves. This behavior may only aim to stock leaves (i.e. to ensure food availability) rather than conditioning them through decay (i.e. to improve food quality). Analysis of gut contents showed that vascular plant material was the dominant food item (83.3 ± 4.6%), followed by sediment (9.2 ± 4.6%) but no animal materials were recorded. N. trispinosum therefore relies minimally on animal food but are capable of removing 50% of the daily leaf litter production. Elemental C, N analysis shows that sediment inside the burrow is a sufficient potential food source (C/N = 13 to 15). While having a lower C/N ratio than fresh green or yellow leaves, the N content of sediment (∼0.1%) was significantly lower than those of mangrove leaves (0.3-0.9%), and may thus

  2. Study of the formation and solution properties of worm-like micelles formed using both N-hexadecyl-N-methylpiperidinium bromide-based cationic surfactant and anionic surfactant.

    Directory of Open Access Journals (Sweden)

    Zhihu Yan

    Full Text Available The viscoelastic properties of worm-like micelles formed by mixing the cationic surfactant N-hexadecyl-N-methylpiperidinium bromide (C16MDB with the anionic surfactant sodium laurate (SL in aqueous solutions were investigated using rheological measurements. The effects of sodium laurate and temperature on the worm-like micelles and the mechanism of the observed shear thinning phenomenon and pseudoplastic behavior were systematically investigated. Additionally, cryogenic transmission electron microscopy images further ascertained existence of entangled worm-like micelles.

  3. of surfactant replacement therapy at Johannesburg Hospital ...

    African Journals Online (AJOL)

    Objective. To assess the impact of surfactant replacement therapy (SRl) on the outcome of hyaline membrane disease (HMD) and to assess the cost implications of a policy of selective administration of artificial surfactant. Design. The short-term outcome of 103 newborns ventilated for HMD (61 selected for SRT according to ...

  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 effects on soil aggregate tensile strength

    Science.gov (United States)

    Little is known regarding a soil aggregate's tensile strength response to surfactants that may be applied to alleviate soil water repellency. Two laboratory investigations were performed to determine surfactant effects on the tensile strength of 1) Ap horizons of nine wettable, agricultural soils co...

  6. Measuring surfactant concentration in plating solutions

    Science.gov (United States)

    Bonivert, William D.; Farmer, Joseph C.; Hachman, John T.

    1989-01-01

    An arrangement for measuring the concentration of surfactants in a electrolyte containing metal ions includes applying a DC bias voltage and a modulated voltage to a counter electrode. The phase angle between the modulated voltage and the current response to the modulated voltage at a working electrode is correlated to the surfactant concentration.

  7. Surfactant Adsorption: A Revised Physical Chemistry Lab

    Science.gov (United States)

    Bresler, Marc R.; Hagen, John P.

    2008-01-01

    Many physical chemistry lab courses include an experiment in which students measure surface tension as a function of surfactant concentration. In the traditional experiment, the data are fit to the Gibbs isotherm to determine the molar area for the surfactant, and the critical micelle concentration is used to calculate the Gibbs energy of micelle…

  8. Surfactants and submicron sea spray generation

    NARCIS (Netherlands)

    Sellegri, K.; O'Dowd, C.D.; Yoon, Y.J.; Jennings, S.G.; Leeuw, G. de

    2006-01-01

    Laboratory experiments have been carried out to elucidate the role of surfactants on the primary marine aerosol production of submicron marine aerosols. A synthetic surfactant SDS was used in conjunction with artificially generated seawater, and the resultant bubble-mediated aerosol produced was

  9. Structure-property relationship of quinuclidinium surfactants--Towards multifunctional biologically active molecules.

    Science.gov (United States)

    Skočibušić, Mirjana; Odžak, Renata; Štefanić, Zoran; Križić, Ivana; Krišto, Lucija; Jović, Ozren; Hrenar, Tomica; Primožič, Ines; Jurašin, Darija

    2016-04-01

    Motivated by diverse biological and pharmacological activity of quinuclidine and oxime compounds we have synthesized and characterized novel class of surfactants, 3-hydroxyimino quinuclidinium bromides with different alkyl chains lengths (CnQNOH; n=12, 14 and 16). The incorporation of non conventional hydroxyimino quinuclidinium headgroup and variation in alkyl chain length affects hydrophilic-hydrophobic balance of surfactant molecule and thereby physicochemical properties important for its application. Therefore, newly synthesized surfactants were characterized by the combination of different experimental techniques: X-ray analysis, potentiometry, electrical conductivity, surface tension and dynamic light scattering measurements, as well as antimicrobial susceptibility tests. Comprehensive investigation of CnQNOH surfactants enabled insight into structure-property relationship i.e., way in which the arrangement of surfactant molecules in the crystal phase correlates with their solution behavior and biologically activity. The synthesized CnQNOH surfactants exhibited high adsorption efficiency and relatively low critical micelle concentrations. In addition, all investigated compounds showed very potent and promising activity against Gram-positive and clinically relevant Gram-negative bacterial strains compared to conventional antimicrobial agents: tetracycline and gentamicin. The overall results indicate that bicyclic headgroup with oxime moiety, which affects both hydrophilicity and hydrophobicity of CnQNOH molecule in addition to enabling hydrogen bonding, has dominant effect on crystal packing and physicochemical properties. The unique structural features of cationic surfactants with hydroxyimino quinuclidine headgroup along with diverse biological activity have made them promising structures in novel drug discovery. Obtained fundamental understanding how combination of different functionalities in a single surfactant molecule affects its physicochemical

  10. Control of stain geometry by drop evaporation of surfactant containing dispersions.

    Science.gov (United States)

    Erbil, H Yildirim

    2015-08-01

    Control of stain geometry by drop evaporation of surfactant containing dispersions is an important topic of interest because it plays a crucial role in many applications such as forming templates on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials. This paper presents a review of the published articles on the diffusive drop evaporation of pure liquids (water), the surfactant stains obtained from evaporating drops that do not contain dispersed particles and deposits obtained from drops containing polymer colloids and carbon based particles such as carbon nanotubes, graphite and fullerenes. Experimental results of specific systems and modeling attempts are discussed. This review also has some special subtopics such as suppression of coffee-rings by surfactant addition and "stick-slip" behavior of evaporating nanosuspension drops. In general, the drop evaporation process of a surfactant/particle/substrate system is very complex since dissolved surfactants adsorb on both the insoluble organic/inorganic micro/nanoparticles in the drop, on the air/solution interface and on the substrate surface in different extends. Meanwhile, surfactant adsorbed particles interact with the substrate giving a specific contact angle, and free surfactants create a solutal Marangoni flow in the drop which controls the location of the particle deposition together with the rate of evaporation. In some cases, the presence of a surfactant monolayer at the air/solution interface alters the rate of evaporation. At present, the magnitude of each effect cannot be predicted adequately in advance and consequently they should be carefully studied for any system in order to control the shape and size of the final deposit. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Deuterium retention in molten salt electrodeposition tungsten coatings

    International Nuclear Information System (INIS)

    Zhou, Hai-Shan; Xu, Yu-Ping; Sun, Ning-Bo; Zhang, Ying-Chun; Oya, Yasuhisa; Zhao, Ming-Zhong; Mao, Hong-Min; Ding, Fang; Liu, Feng; Luo, Guang-Nan

    2016-01-01

    Highlights: • We investigate D retention in electrodeposition W coatings. • W coatings are exposed to D plasmas in the EAST tokamak. • A cathodic current density dependence on D retention is found. • Electrodeposition W exhibits lower D retention than VPS-W. - Abstract: Molten salt electrodeposition is a promising technology to manufacture the first wall of a fusion reactor. Deuterium (D) retention behavior in molten salt electrodeposition tungsten (W) coatings has been investigated by D-plasma exposure in the EAST tokamak and D-ion implantation in an ion beam facility. Tokamak exposure experiments demonstrate that coatings prepared with lower current density exhibit less D retention and milder surface damage. Deuterium-ion implantation experiments indicate the D retention in the molten salt electrodeposition W is less than that in vacuum plasma spraying W and polycrystalline W.

  12. Surfactant-controlled etching of ion track nanopores and its practical applications in membrane technology

    International Nuclear Information System (INIS)

    Apel, P.Yu.; Blonskaya, I.V.; Dmitriev, S.N.; Mamonova, T.I.; Orelovitch, O.L.; Sartowska, B.; Yamauchi, Yu.

    2008-01-01

    The effect of surfactants on chemical development of ion tracks in polymers has been studied. It has been shown that surface-active agents added to an alkaline etching solution adsorb on the polymer surface at the pore entrances. This reduces the etch rate, which leads to the formation of pores tapered toward the surface. Self-assembly of surfactant molecules at the pore entrance creates a barrier for their penetration into the etched-out nanopores, whereas hydroxide ions diffuse freely. Due to this, the internal pore volume grows faster than the pore surface diameter. The ability to control pore shape is demonstrated with the fabrication of profiled nano- and micropores in polyethylene terephthalate, polycarbonate. Some earlier published data on small track-etched pores in polycarbonate (in particular, the pore diameter vs. etching time curves measured conductometrically) have been revised in light of the above findings. Adding surfactants to chemical etchants makes it possible to optimize the structure of track membranes, thus improving their retention and permeation properties. Asymmetric membranes with thin skin retention layers have been produced and their performance studied

  13. Surfactant-controlled etching of ion track nanopores and its practical applications in membrane technology

    Energy Technology Data Exchange (ETDEWEB)

    Apel, P.Yu. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)], E-mail: apel@nrmail.jinr.ru; Blonskaya, I.V.; Dmitriev, S.N.; Mamonova, T.I.; Orelovitch, O.L. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Sartowska, B. [Institute of Nuclear Chemistry and Technology, Dorodna Street 16, 03-195 Warsaw (Poland); Yamauchi, Yu. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

    2008-08-15

    The effect of surfactants on chemical development of ion tracks in polymers has been studied. It has been shown that surface-active agents added to an alkaline etching solution adsorb on the polymer surface at the pore entrances. This reduces the etch rate, which leads to the formation of pores tapered toward the surface. Self-assembly of surfactant molecules at the pore entrance creates a barrier for their penetration into the etched-out nanopores, whereas hydroxide ions diffuse freely. Due to this, the internal pore volume grows faster than the pore surface diameter. The ability to control pore shape is demonstrated with the fabrication of profiled nano- and micropores in polyethylene terephthalate, polycarbonate. Some earlier published data on small track-etched pores in polycarbonate (in particular, the pore diameter vs. etching time curves measured conductometrically) have been revised in light of the above findings. Adding surfactants to chemical etchants makes it possible to optimize the structure of track membranes, thus improving their retention and permeation properties. Asymmetric membranes with thin skin retention layers have been produced and their performance studied.

  14. American Recovery and Reinvestment Act of 2009: Final Report on Customer Acceptance, Retention, and Response to Time-Based Rates from Consumer Behavior Studies

    Energy Technology Data Exchange (ETDEWEB)

    Cappers, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Analysis and Environmental Impacts Division; Scheer, Rich [Scheer Ventures LLC, Takoma Park, MD (United States)

    2018-03-07

    Time-based rate programs, enabled by utility investments in advanced metering infrastructure (AMI), are increasingly being considered by utilities as tools to reduce peak demand and enable customers to better manage consumption and costs. Under the Smart Grid Investment Grant Program (SGIG), the U.S. Department of Energy (DOE) partnered with several electric utilities to conduct consumer behavior studies (CBS). The goals involved applying randomized and controlled experimental designs for estimating customer responses more precisely and credibly to advance understanding of time-based rates and customer systems, and provide new information for improving program designs, implementation strategies, and evaluations. The intent was to produce more robust and credible analysis of impacts, costs, benefits, and lessons learned and assist utility and regulatory decision makers in evaluating investment opportunities involving time-based rates.

  15. Molecular-thermodynamic theory of micellization of pH-sensitive surfactants.

    Science.gov (United States)

    Goldsipe, Arthur; Blankschtein, Daniel

    2006-04-11

    A predictive, molecular-thermodynamic theory is developed to model the micellization of pH-sensitive surfactants. The theory combines a molecular-thermodynamic description of micellization in binary surfactant mixtures with the protonation equilibrium of the surfactant monomers. The thermodynamic component of the theory models the pH-mediated equilibrium between micelles, surfactant monomers, and counterions. These counterions may originate from the surfactant or from added salt, acid, or base. The molecular component of the theory models the various contributions to the free energy of micellization, which corresponds to the free-energy change associated with forming a mixed micelle from the protonated and deprotonated forms of the surfactant and from the bound counterions. The free energy of micellization includes hydrophobic, interfacial, packing, steric, electrostatic, and entropic contributions, which are all calculated molecularly. The theory also requires knowledge of the surfactant molecular structure and the solution conditions, including the temperature and the amount of any added salt, acid, or base. To account for the pH sensitivity of the surfactant, the theory requires knowledge of the surfactant monomer equilibrium deprotonation constant (pK1), which may be obtained from experimental titration data obtained below the critical micelle concentration (cmc). The theory can be utilized to predict the equilibrium micelle and solution properties, including the cmc, the micelle composition, the micelle shape and aggregation number, the solution pH, and the micelle deprotonation equilibrium constant (pKm). Theoretical predictions of the cmc, the micelle aggregation number, and the pKm compare favorably with the available experimental data for alkyldimethylamine oxide surfactants. This class of pH-sensitive surfactants exhibits a form of self-synergy, which has previously been attributed to hydrogen-bond formation at the micelle interface. Instead, we show that

  16. Evaluation of the presence of major anionic surfactants in marine sediments.

    Science.gov (United States)

    Cantarero, S; Camino-Sánchez, F J; Zafra-Gómez, A; Ballesteros, O; Navalón, A; Vílchez, J L; Verge, C; Reis, M S; Saraiva, P M

    2012-03-01

    The contamination of aquatic environments has become the focus of increasing regulation and public concern due to their potential and unknown negative effects on the ecosystems. The present work develops a monitoring and statistical study, based on the analysis of variance test (ANOVA) and the multivariable analysis, both for insoluble soap and LAS in order to compare the behavior of different anionic surfactants in this environmental compartment. First, a novel and successfully validated methodology to analyze insoluble soap in these samples is developed. The matrix effect and the comparison of different extraction techniques were also performed. The optimized analytical methodologies were applied to 48 representative samples collected from the Almeria Coast (Spain) and then a statistical analysis to correlate anionic surfactant concentration and several variables associated with marine sediment samples was also developed. The results obtained showed relevant conclusions related to the environmental behavior of anionic surfactants in marine sediments. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Solubilization and Interaction Studies of Bile Salts with Surfactants and Drugs: a Review.

    Science.gov (United States)

    Malik, Nisar Ahmad

    2016-05-01

    In this review, bile salt, bile salt-surfactant, and bile salt-drug interactions and their solubilization studies are mainly focused. Usefulness of bile salts in digestion, absorption, and excretion of various compounds and their rare properties in ordering the shape and size of the micelles owing to the presence of hydrophobic and hydrophilic faces are taken into consideration while compiling this review. Bile salts as potential bio-surfactants to solubilize drugs of interest are also highlighted. This review will give an insight into the selection of drugs in different applications as their properties get modified by interaction with bile salts, thus influencing their solution behavior which, in turn, modifies the phase-forming behavior, microemulsion, and clouding phenomenon, besides solubilization. Finally, their future perspectives are taken into consideration to assess their possible uses as bio-surfactants without side effects to human beings.

  18. Surfactant selection principle for reducing critical micelle concentration in mixtures of oppositely charged gemini surfactants.

    Science.gov (United States)

    Liu, Zhang; Fan, Yaxun; Tian, Maozhang; Wang, Ruijuan; Han, Yuchun; Wang, Yilin

    2014-07-15

    Cationic quaternary ammonium gemini surfactants C(n)H(2n+1)(CH3)2N(+)CH2CHCHCH2(CH3)2N(+)C(n)H(2n+1)2Br(-) (C(n)C4C(n), n = 12, 8, 6) with alkyl spacers, C(n)H(2n+1)(CH3)2N(+)CH2CHOHCHOHCH2(CH3)2N(+)C(n)H(2n+1)2Br(-) (C(n)C4(OH)2C(n), n = 12, 8, 6, 4) with two hydroxyl groups in alkyl spacers, and cationic ammonium single-chain surfactants C(n)H(2n+1)(CH3)2N(+)Br(-) (C(n)TAB, n = 12, 8, 6) have been chosen to fabricate oppositely charged surfactant mixtures with anionic sulfonate gemini surfactant C12H25N(CH2CH2CH2SO3(-))CH2CH2CH2(CH3)2N(CH2CH2CH2SO3(-))C12H252Na (C12C3C12(SO3)2). Surface tension, electrical conductivity, and isothermal titration microcalorimetry (ITC) were used to study their surface properties, aggregation behaviors, and intermolecular interactions. The mixtures of C12C3C12(SO3)2/C(n)C4(OH)2C(n) (n = 12, 8) and C12C3C12(SO3)2/C12C4C12 show anomalous larger critical micelle concentration (CMC) than C12C3C12(SO3)2, while the mixtures of C12C3C12(SO3)2/C(n)C4(OH)2C(n) (n = 6, 4), C12C3C12(SO3)2/C(n)C4(OH)2C(n) (n = 6, 4), and C12C3C12(SO3)2/C(n)TAB (n = 12, 8, 6) exhibit much lower CMC than C12C3C12(SO3)2. The results indicate that strong hydrophobic interactions between the alkyl chains assisted by strong electrostatic attractions between the headgroups and hydrogen bonds between the spacers lead to the formation of less surface active premicellar aggregates in bulk solution, resulting in the increase of CMC. If these interactions are weakened or inhibited, less surface active premicellar aggregates are no longer formed in the mixtures, and thus the CMC values are reduced. The work reveals that the combination of two surfactants with great self-assembling ability separately may have strong intermolecular binding interactions; however, their mixtures do not always generate superior synergism properties. Only moderate intermolecular interaction can generate the strongest synergism in CMC reduction.

  19. Spontaneous vesicle phase formation by pseudogemini surfactants in aqueous solutions.

    Science.gov (United States)

    Sun, Nan; Shi, Lijuan; Lu, Fei; Xie, Shuting; Zheng, Liqiang

    2014-08-14

    The phase behavior of a kind of pseudogemini surfactant in aqueous solutions, formed by the mixture of sodium dodecyl benzene sulfonate (SDBS) and butane-1,4-bis (methylimidazolium bromide) ([mim-C4-mim]Br2) or butane-1,4-bis(methylpyrrolidinium bromide) ([mpy-C4-mpy]Br2) in a molar ratio of 2 : 1, is reported in the present work. When [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 is mixed with SDBS in aqueous solutions, one cationic [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 molecule "bridges" two SDBS molecules by noncovalent interactions (e.g. electrostatic, π-π stacking, and σ-π interactions), behaving like a pseudogemini surfactant. Vesicles can be formed by this kind of pseudogemini surfactant, determined by freeze-fracture transmission electron microscopy (FF-TEM) or cryogenic-transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). The mixed system of sodium dodecyl sulfate (SDS) with [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 was also constructed, and only micelles were observed. We infer that a pseudogemini surfactant is formed under the synergic effect of electrostatic, π-π stacking, and σ-π interactions in the SDBS/[mim-C4-mim]Br2/H2O system, while electrostatic attraction and hydrophobic interactions may provide the directional force for vesicle formation in the SDBS/[mpy-C4-mpy]Br2/H2O system.

  20. A technique to train new oculomotor behavior in patients with central macular scotomas during reading related tasks using scanning laser ophthalmoscopy: immediate functional benefits and gains retention

    Directory of Open Access Journals (Sweden)

    Lorincz Erika N

    2006-11-01

    Full Text Available Abstract Background Reading with a central scotoma involves the use of preferred retinal loci (PRLs that enable both letter resolution and global viewing of word. Spontaneously developed PRLs however often privilege spatial resolution and, as a result, visual span is commonly limited by the position of the scotoma. In this study we designed and performed the pilot trial of a training procedure aimed at modifying oculomotor behavior in subjects with central field loss. We use an additional fixation point which, when combined with the initial PRL, allows the fulfillment of both letter resolution and global viewing of words. Methods The training procedure comprises ten training sessions conducted with the scanning laser ophthalmoscope (SLO. Subjects have to read single letters and isolated words varying in length, by combining the use of their initial PRL with the one of an examiner's selected trained retinal locus (TRL. We enrolled five subjects to test for the feasibility of the training technique. They showed stable maculopathy and persisting major reading difficulties despite previous orthoptic rehabilitation. We evaluated ETDRS visual acuity, threshold character size for single letters and isolated words, accuracy for paragraphed text reading and reading strategies before, immediately after SLO training, and three months later. Results Training the use of multiple PRLs in patients with central field loss is feasible and contributes to adapt oculomotor strategies during reading related tasks. Immediately after SLO training subjects used in combination with their initial PRL the examiner's selected TRL and other newly self-selected PRLs. Training gains were also reflected in ETDRS acuity, threshold character size for words of different lengths and in paragraphed text reading. Interestingly, subjects benefited variously from the training procedure and gains were retained differently as a function of word length. Conclusion We designed a new

  1. Exogenous Pulmonary Surfactant as a Vehicle for Antimicrobials: Assessment of Surfactant-Antibacterial Interactions In Vitro

    Directory of Open Access Journals (Sweden)

    Alexei Birkun

    2014-01-01

    Full Text Available Owing to its unique surface-active properties, an exogenous pulmonary surfactant may become a promising drug delivery agent, in particular, acting as a vehicle for antibiotics in topical treatment of pneumonia. The purpose of this study was to assess a mutual influence of natural surfactant preparation and three antibiotics (amikacin, cefepime, and colistimethate sodium in vitro and to identify appropriate combination(s for subsequent in vivo investigations of experimental surfactant/antibiotic mixtures. Influence of antibiotics on surface-active properties of exogenous surfactant was assessed using the modified Pattle method. Effects of exogenous surfactant on antibacterial activity of antimicrobials against Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa were evaluated using conventional microbiologic procedures. Addition of amikacin or cefepime to surfactant had no significant influence on surface-active properties of the latter. Obvious reduction of surface-active properties was confirmed for surfactant/colistimethate composition. When suspended with antibiotics, surfactant either had no impact on their antimicrobial activity (amikacin or exerted mild to moderate influence (reduction of cefepime bactericidal activity and increase of colistimethate bacteriostatic activity against S. aureus and P. aeruginosa. Considering favorable compatibility profile, the surfactant/amikacin combination is advisable for subsequent investigation of joint surfactant/antibacterial therapy in animals with bacterial pneumonia.

  2. Exogenous Pulmonary Surfactant as a Vehicle for Antimicrobials: Assessment of Surfactant-Antibacterial Interactions In Vitro

    Science.gov (United States)

    2014-01-01

    Owing to its unique surface-active properties, an exogenous pulmonary surfactant may become a promising drug delivery agent, in particular, acting as a vehicle for antibiotics in topical treatment of pneumonia. The purpose of this study was to assess a mutual influence of natural surfactant preparation and three antibiotics (amikacin, cefepime, and colistimethate sodium) in vitro and to identify appropriate combination(s) for subsequent in vivo investigations of experimental surfactant/antibiotic mixtures. Influence of antibiotics on surface-active properties of exogenous surfactant was assessed using the modified Pattle method. Effects of exogenous surfactant on antibacterial activity of antimicrobials against Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa were evaluated using conventional microbiologic procedures. Addition of amikacin or cefepime to surfactant had no significant influence on surface-active properties of the latter. Obvious reduction of surface-active properties was confirmed for surfactant/colistimethate composition. When suspended with antibiotics, surfactant either had no impact on their antimicrobial activity (amikacin) or exerted mild to moderate influence (reduction of cefepime bactericidal activity and increase of colistimethate bacteriostatic activity against S. aureus and P. aeruginosa). Considering favorable compatibility profile, the surfactant/amikacin combination is advisable for subsequent investigation of joint surfactant/antibacterial therapy in animals with bacterial pneumonia. PMID:24876994

  3. Different effects of surfactant proteins B and C - implications for development of synthetic surfactants.

    Science.gov (United States)

    Curstedt, Tore; Johansson, Jan

    2010-06-01

    Treatment of premature newborn rabbits with synthetic surfactants containing a surfactant protein C analogue in a simple phospholipid mixture gives similar tidal volumes as treatment with poractant alfa (Curosurf(R)) but ventilation with a positive end-expiratory pressure (PEEP) is needed for this synthetic surfactant to stabilize the alveoli at end-expiration. The effect on lung gas volumes seems to depend on the structure of the peptide since treatment with a synthetic surfactant containing the 21-residue peptide (LysLeu(4))(4)Lys (KL(4)) gives low lung gas volumes in experiments also performed with PEEP. Surfactant preparations containing both surfactant proteins B and C or their analogues prevent alveolar collapse at end-expiration even if ventilated without PEEP. Treatment of premature newborn rabbits with different natural surfactants indicates that both the lipid composition and the proteins are important in order to stabilize the alveoli at end-expiration. Synthetic surfactants containing two peptides may be able to replace natural surfactants within the near future but more trials need to be performed before any conclusion can be drawn about the ideal composition of this new generation of synthetic surfactants. Copyright 2010 S. Karger AG, Basel.

  4. 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 ...

  5. Post-deposition early-phase migration and retention behavior of radiocesium in a litter-mineral soil system in a Japanese deciduous forest affected by the Fukushima nuclear accident.

    Science.gov (United States)

    Koarashi, Jun; Nishimura, Syusaku; Nakanishi, Takahiro; Atarashi-Andoh, Mariko; Takeuchi, Erina; Muto, Kotomi

    2016-12-01

    The fate of radiocesium ( 137 Cs) derived from the Fukushima nuclear accident and associated radiation risks are largely dependent on its migration and retention behavior in the litter-soil system of Japanese forest ecosystems. However, this behavior has not been well quantified. We established field lysimeters in a Japanese deciduous broad-leaved forest soon after the Fukushima nuclear accident to continuously monitor the downward transfer of 137 Cs at three depths: the litter-mineral soil boundary and depths of 5 cm and 10 cm in the mineral soil. Observations were conducted at two sites within the forest from May 2011 to May 2015. Results revealed similar temporal and depth-wise variations in 137 Cs downward fluxes for both sites. The 137 Cs downward fluxes generally decreased year by year at all depths, indicating that 137 Cs was rapidly leached from the forest-floor litter layer and was then immobilized in the upper (0-5 cm) mineral soil layer through its interaction with clay minerals. The 137 Cs fluxes also showed seasonal variation, which was in accordance with variations in the throughfall and soil temperature at the sites. There was no detectable 137 Cs flux at a depth of 10 cm in the mineral soil in the third and fourth years after the accident. The decreased inventory of mobile (or bioavailable) 137 Cs observed during early stages after deposition indicates that the litter-soil system in the Japanese deciduous forest provides only a temporary source for 137 Cs recycling in plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. Impact of model perfume molecules on the self-assembly of anionic surfactant sodium dodecyl 6-benzene sulfonate.

    Science.gov (United States)

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

    2013-03-12

    The impact of two model perfumes with differing degrees of hydrophobicity/hydrophilicity, linalool (LL) and phenylethanol (PE), on the solution structure of anionic surfactant sodium dodecyl 6-benzene sulfonate, LAS-6, has been studied by small angle neutron scattering, SANS. For both types of perfume molecules, complex phase behavior is observed. The phase behavior depends upon the concentration, surfactant/perfume composition, and type of perfume. The more hydrophilic perfume PE promotes the formation of more highly curved structures. At relatively low surfactant concentrations, small globular micelles, L1, are formed. These become perfume droplets, L(sm), stabilized by the surfactant at much higher perfume solution compositions. At higher surfactant concentrations, the tendency of LAS-6 to form more planar structures is evident. The more hydrophobic linalool promotes the formation of more planar structures. Combined with the greater tendency of LAS-6 to form planar structures, this results in the planar structures dominating the phase behavior for the LAS-6/linalool mixtures. For the LAS-6/linalool mixture, the self-assembly is in the form of micelles only at the lowest surfactant and perfume concentrations. Over most of the concentration-composition space explored, the structures are predominantly lamellar, L(α), or vesicle, L(v), or in the form of a lamellar/micellar coexistence. At low and intermediate amounts of LL, a significantly different structure is observed, and the aggregates are in the form of small, relatively monodisperse vesicles (i.e., nanovesicles), L(sv).

  12. Determination of sildenafil by preconcentration on surfactant coated polymeric resin followed by spectrofluorimetry

    Directory of Open Access Journals (Sweden)

    Chien C. Wang

    2013-06-01

    Full Text Available The illicit addition of phosphodiesterase type-5 (PDE-5 inhibitors like sildenafil (Viagra in product offered as herbal medicine or dietary supplement for male erectile dysfunction has concerned authorities in recent times. In this paper, we proposed a sensitive surfactant-coated Amberlite XAD™ resin for sildenafil preconcentration method with spectrofluorimetric detection. Retention capacity of micellar coated XAD resin for sildenafil was studied and the obtained eluate was measured by spectrofluorometer at excitation and emission wavelengths of 350 and 430nm, respectively. This method allowed the detection of sildenafil at 0.15ng/mL with linear range of 0.0003–7.0μg/mL. The method has been successfully applied to the analysis of some local commercially available herbal medicines and urine. Keywords: Sildenafil, Herbal medicines, Spectrofluorimetric analysis, Surfactant

  13. Gemini surfactants from natural amino acids.

    Science.gov (United States)

    Pérez, Lourdes; Pinazo, Aurora; Pons, Ramon; Infante, Mrosa

    2014-03-01

    In this review, we report the most important contributions in the structure, synthesis, physicochemical (surface adsorption, aggregation and phase behaviour) and biological properties (toxicity, antimicrobial activity and biodegradation) of Gemini natural amino acid-based surfactants, and some potential applications, with an emphasis on the use of these surfactants as non-viral delivery system agents. Gemini surfactants derived from basic (Arg, Lys), neutral (Ser, Ala, Sar), acid (Asp) and sulphur containing amino acids (Cys) as polar head groups, and Geminis with amino acids/peptides in the spacer chain are reviewed. © 2013.

  14. Mechanism of bacterial inactivation by cationic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Pavlova, I.B.; Samoylenko, I.I.

    1985-03-01

    The mechanism of bacteriocidal action of the cationic surfactant dimethylbenzylammonium chloride was studied on exposure of Staphylococcus aureus, Streptococcus faecium, Bacillus subtilis and Escherichia coli to different concentrations of the agent and determinations of survival plots. The data showed that the surfactant was bacteriocidal for all the bacteria tested at a concentration of 0.0001%, but more efficient in the case of the gram positives. Electron microscopy showed considerable damage and dissarrangement of the cytoplasmic membrane, indicating that the killing mechanism involved this organelle. It appears that cationic surfactants may constitute effective disinfectant preparations. 9 references, 2 figures.

  15. Surfactant-Assisted Coal Liquefaction

    Science.gov (United States)

    Hickey, Gregory S.; Sharma, Pramod K.

    1993-01-01

    Obtaining liquid fuels from coal which are economically competitive with those obtained from petroleum based sources is a significant challenge for the researcher as well as the chemical industry. Presently, the economics of coal liquefaction are not favorable because of relatively intense processing conditions (temperatures of 430 degrees C and pressures of 2200 psig), use of a costly catalyst, and a low quality product slate of relatively high boiling fractions. The economics could be made more favorable by achieving adequate coal conversions at less intense processing conditions and improving the product slate. A study has been carried out to examine the effect of a surfactant in reducing particle agglomeration and improving hydrodynamics in the coal liquefaction reactor to increase coal conversions...

  16. Sexual Dimorphism in Stature (SDS, Jealousy and Mate Retention

    Directory of Open Access Journals (Sweden)

    Gayle Brewer

    2010-10-01

    Full Text Available Previous research has investigated the manner in which absolute height impacts on jealousy and mate retention. Although relative height is also important, little information exists about the potential influence of sexual dimorphism in stature (SDS within established relationships. The current study investigated the relationship between SDS and the satisfaction, jealousy and mate retention behaviors reported by men and women. Heterosexual men (n = 98 and women (n = 102 completed a questionnaire. Men in high SDS relationships reported the lowest levels of cognitive and behavioral jealousy, although the impact of SDS on relationship satisfaction was less clear. SDS was not associated with the overall use of mate retention strategies; SDS did however affect the use of three specific strategies (vigilance, monopolization of time, love and care. SDS did not affect women's relationship satisfaction, jealousy (cognitive, behavioral, or emotional or the use of mate retention strategies (with the exception of resource display.

  17. Isolation of Surfactant-Resistant Bacteria from Natural, Surfactant-Rich Marine Habitats▿

    OpenAIRE

    Plante, Craig J.; Coe, Kieran M.; Plante, Rebecca G.

    2008-01-01

    Environmental remediation efforts often utilize either biodegradative microbes or surfactants, but not in combination. Coupling both strategies holds the potential to dramatically increase the rate and extent of remediation because surfactants can enhance the bioavailability of contaminants to microbes. However, many surfactants permeabilize bacterial cell membranes and are effective disinfectants. An important goal then is to find or genetically modify microorganisms that possess both desira...

  18. Pulmonary Surfactants for Acute and Chronic Lung Diseases (Part I

    Directory of Open Access Journals (Sweden)

    O. A. Rozenberg

    2014-01-01

    Full Text Available Part 1 of the review gives information on the composition and properties of a pulmonary surfactant and quantitative and qual itative impairments in the pulmonary surfactant system in different neonatal and adult abnormalities and describes the composition of commercial synthetic and natural surfactants. The results of surfactant therapy for respiratory distress syndrome and other lung diseases with secondary surfactant deficiency in the newborns are analyzed.

  19. An Energetic Analysis of the Phase Separation in Non-Ionic Surfactant Mixtures: The Role of the Headgroup Structure

    Directory of Open Access Journals (Sweden)

    José Manuel Hierrezuelo

    2014-08-01

    Full Text Available The main goal of this paper was to examine the effect of the hydrophilic surfactant headgroup on the phase behavior of non-ionic surfactant mixtures. Four mixed systems composed of an ethoxylated plus sugar-based surfactants, each having the same hydrophobic tail, were investigated. We found that the hydrophilicity of the surfactant inhibits the tendency of the system to phase separate, which is sensitive to the presence of NaCl. Applying a classical phase separation thermodynamic model, the corresponding energy parameters were evaluated. In all cases, the parameters were found to depend on the type of nonionic surfactant, its concentration in the micellar solution and the presence of NaCl in the medium. The experimental results can be explained by assuming the phase separation process takes place as a result of reduced hydration of the surfactant headgroup caused by a temperature increase. The enthalpy-entropy compensation plot exhibits excellent linearity. We found that all the mixed surfactant systems coincided on the same straight line, the compensation temperature being lower in the presence of NaCl.

  20. Particle and surfactant interactions effected polar and dispersive components of interfacial energy in nanocolloids

    Science.gov (United States)

    Harikrishnan, A. R.; Das, Sarit K.; Agnihotri, Prabhat K.; Dhar, Purbarun

    2017-08-01

    We segregate and report experimentally for the first time the polar and dispersive interfacial energy components of complex nanocolloidal dispersions. In the present study, we introduce a novel inverse protocol for the classical Owens Wendt method to determine the constitutive polar and dispersive elements of surface tension in such multicomponent fluidic systems. The effect of nanoparticles alone and aqueous surfactants alone are studied independently to understand the role of the concentration of the dispersed phase in modulating the constitutive elements of surface energy in fluids. Surfactants are capable of altering the polar component, and the combined particle and surfactant nanodispersions are shown to be effective in modulating the polar and dispersive components of surface tension depending on the relative particle and surfactant concentrations as well as the morphological and electrostatic nature of the dispersed phases. We observe that the combined surfactant and particle colloid exhibits a similar behavior to that of the particle only case; however, the amount of modulation of the polar and dispersive constituents is found to be different from the particle alone case which brings to the forefront the mechanisms through which surfactants modulate interfacial energies in complex fluids. Accordingly, we are able to show that the observations can be merged into a form of quasi-universal trend in the trends of polar and dispersive components in spite of the non-universal character in the wetting behavior of the fluids. We analyze the different factors affecting the polar and dispersive interactions in such complex colloids, and the physics behind such complex interactions has been explained by appealing to the classical dispersion theories by London, Debye, and Keesom as well as by Derjaguin-Landau-Verwey-Overbeek theory. The findings shed light on the nature of wetting behavior of such complex fluids and help in predicting the wettability and the degree of

  1. 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.

  2. Surface film formation in vitro by infant and therapeutic surfactants: role of surfactant protein B.

    Science.gov (United States)

    Danhaive, Olivier; Chapin, Cheryl; Horneman, Hart; Cogo, Paola E; Ballard, Philip L

    2015-02-01

    Pulmonary surfactant provides an alveolar surface-active film that is critical for normal lung function. Our objective was to determine in vitro film formation properties of therapeutic and infant surfactants and the influence of surfactant protein (SP)-B content. We used a multiwell fluorescent assay measuring maximum phospholipid surface accumulation (Max), phospholipid concentration required for half-maximal film formation (½Max), and time for maximal accumulation (tMax). Among five therapeutic surfactants, calfactant (highest SP-B content) had film formation values similar to natural surfactant, and addition of SP-B to beractant (lowest SP-B) normalized its Max value. Addition of budesonide to calfactant did not adversely affect film formation. In tracheal aspirates of preterm infants with evolving chronic lung disease, SP-B content correlated with ½Max and tMax values, and SP-B supplementation of SP-B-deficient infant surfactant restored normal film formation. Reconstitution of normal surfactant indicated a role for both SP-B and SP-C in film formation. Film formation in vitro differs among therapeutic surfactants and is highly dependent on SP-B content in infant surfactant. The results support a critical role of SP-B for promoting surface film formation.

  3. Data on Retention

    NARCIS (Netherlands)

    van Wanrooij, Ward; Pras, Aiko; Schönwälder, Jürgen; Serrat, Joan

    2005-01-01

    Proposed EU regulations on data retention could require every provider to keep accounting logs of its customers Internet usage. Although the technical consequences of these requirements have been investigated by consultancy companies, this paper investigates what this accounting data could be, how

  4. Tritium retention in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Dylla, H.F.; Wilson, K.L. (eds.)

    1988-04-01

    This report discusses the materials physics related to D-T operation in TFTR. Research activities are described pertaining to basic studies of hydrogenic retention in graphite, hydrogen recycling phenomena, first-wall and limiter conditioning, surface analysis of TFTR first-wall components, and estimates of the tritium inventory.

  5. Wetting kinetics of water nano-droplet containing non-surfactant nanoparticles: A molecular dynamics study

    International Nuclear Information System (INIS)

    Lu, Gui; Hu, Han; Sun, Ying; Duan, Yuanyuan

    2013-01-01

    In this Letter, dynamic wetting of water nano-droplets containing non-surfactant gold nanoparticles on a gold substrate is examined via molecular dynamics simulations. The results show that the addition of non-surfactant nanoparticles hinders the nano-second droplet wetting process, attributed to the increases in both surface tension of the nanofluid and friction between nanofluid and substrate. The droplet wetting kinetics decreases with increasing nanoparticle loading and water-particle interaction energy. The observed wetting suppression and the absence of nanoparticle ordering near the contact line of nano-sized droplets differ from the wetting behaviors reported from nanofluid droplets of micron size or larger

  6. 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)

  7. Controlled hypothermia may improve surfactant function in asphyxiated neonates with or without meconium aspiration syndrome.

    Science.gov (United States)

    Autilio, Chiara; Echaide, Mercedes; De Luca, Daniele; Pérez-Gil, Jesús

    2018-01-01

    Whole-body hypothermia (WBH) is used to improve neurological outcomes in perinatal asphyxia. Recent studies suggested a beneficial effect of hypothermia for some types of acute respiratory failure. However, no data are available about the biophysical function of human surfactant during WBH. We investigated whether WBH improves surfactant biophysical properties in asphyxiated neonates with or without meconium aspiration syndrome (MAS). Non-bronchoscopic bronchoalveolar lavage (BAL) has been collected from 10 asphyxiated neonates (2 with MAS, 8 with no lung disease (NLD)) at different time-points (pre-WBH, 24h, 48h, 72h of WBH and post-WBH). Surfactant was extracted and tested by captive bubble surfactometry (CBS) in triplicate, at 37°C and 33.5°C, through initial adsorption and dynamic compression-expansion cycling. Phosphatidylcholine and cholesterol were assayed using enzymatic methods. Clinical data were recorded in real-time. Minimum surface tension under dynamic testing was significantly improved as assessed at 33.5°C compared with its behavior at 37°C in NLD neonates: the difference was evident after at least 72h of WBH and remained significant at 6h after rewarming (72h: p = 0.009; rewarming: p = 0.040). Similar results were obtained in MAS patients whose surfactant activity improved already at 48h of hypothermia. Total cholesterol showed a trend to increase at the first 24-48h of hypothermia in NLD patients. Conversely, hypothermia seemed to reduce the excess of exogenous cholesterol in MAS surfactant. Surfactant biophysical properties may improve after 48-72h of WBH in asphyxiated neonates and the improvement is maintained shortly after rewarming. Due to study limitations, further studies are warranted to better clarify the effects of hypothermia on surfactant activity.

  8. Controlled hypothermia may improve surfactant function in asphyxiated neonates with or without meconium aspiration syndrome.

    Directory of Open Access Journals (Sweden)

    Chiara Autilio

    Full Text Available Whole-body hypothermia (WBH is used to improve neurological outcomes in perinatal asphyxia. Recent studies suggested a beneficial effect of hypothermia for some types of acute respiratory failure. However, no data are available about the biophysical function of human surfactant during WBH. We investigated whether WBH improves surfactant biophysical properties in asphyxiated neonates with or without meconium aspiration syndrome (MAS.Non-bronchoscopic bronchoalveolar lavage (BAL has been collected from 10 asphyxiated neonates (2 with MAS, 8 with no lung disease (NLD at different time-points (pre-WBH, 24h, 48h, 72h of WBH and post-WBH. Surfactant was extracted and tested by captive bubble surfactometry (CBS in triplicate, at 37°C and 33.5°C, through initial adsorption and dynamic compression-expansion cycling. Phosphatidylcholine and cholesterol were assayed using enzymatic methods. Clinical data were recorded in real-time.Minimum surface tension under dynamic testing was significantly improved as assessed at 33.5°C compared with its behavior at 37°C in NLD neonates: the difference was evident after at least 72h of WBH and remained significant at 6h after rewarming (72h: p = 0.009; rewarming: p = 0.040. Similar results were obtained in MAS patients whose surfactant activity improved already at 48h of hypothermia. Total cholesterol showed a trend to increase at the first 24-48h of hypothermia in NLD patients. Conversely, hypothermia seemed to reduce the excess of exogenous cholesterol in MAS surfactant.Surfactant biophysical properties may improve after 48-72h of WBH in asphyxiated neonates and the improvement is maintained shortly after rewarming. Due to study limitations, further studies are warranted to better clarify the effects of hypothermia on surfactant activity.

  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. phosphorus retention data and metadata

    Data.gov (United States)

    U.S. Environmental Protection Agency — phosphorus retention in wetlands data and metadata. This dataset is associated with the following publication: Lane , C., and B. Autrey. Phosphorus retention of...

  11. Retention Measures and Reporting Systems

    National Research Council Canada - National Science Library

    Ropp, Gary

    2003-01-01

    ...) and performed by the Navy Personnel Research and Development Center (NPRDC) to: (1) review current retention measures in use in the Navy, as well as the system used to distribute retention statistics, and (2...

  12. 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...

  13. Lipoplexes formed from sugar-based gemini surfactants undergo a lamellar-to-micellar phase transition at acidic pH. Evidence for a non-inverted membrane-destabilizing hexagonal phase of lipoplexes

    OpenAIRE

    Wasungu, Luc; Stuart, Marc C. A.; Scarzello, Marco; Engberts, Jan B. F. N.; Hoekstra, Dick

    2006-01-01

    The present study aims at a better understanding of the mechanism of transfection mediated by two sugar-based gemini surfactants GS1 and GS2. Previously, these gemini surfactants have been shown to be efficient gene vectors for transfection both in vitro and in vivo. Here, using Nile Red, a solvatochromic fluorescent probe, we investigated the phase behavior of these gemini surfactants in complexes with plasmid DNA, so-called lipoplexes. We found that these lipoplexes undergo a lamellar-to-no...

  14. [Deficiency of surfactant protein: Case report].

    Science.gov (United States)

    Milet, María Beatriz; Mena N, Patricia; Pérez, Héctor I; Espinoza, Tatiana

    Congenital surfactant deficiency is a condition infrequently diagnosed in newborns. A clinical case is presented of surfactant protein B deficiency. A review is performed on the study, treatment and differential diagnosis of surfactant protein deficiencies and infant chronic interstitial lung disease. The case is presented of a term newborn that developed respiratory distress, recurrent pulmonary opacification, and a transient response to the administration of surfactant. Immunohistochemical and genetic studies confirmed the diagnosis of surfactant protein B deficiency. Pulmonary congenital anomalies require a high index of suspicion. Surfactant protein B deficiency is clinically progressive and fatal in the majority of the cases, similar to that of ATP binding cassette subfamily A member 3 (ABCA3) deficiency. Protein C deficiency is insidious and may present with a radiological pulmonary interstitial pattern. Due to the similarity in the histological pattern, genetic studies help to achieve greater certainty in the prognosis and the possibility of providing adequate genetic counselling. Copyright © 2016 Sociedad Chilena de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

  15. Surfactant-dependent macrophage response to polypyrrole-based coatings electrodeposited on Ti6Al7Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mindroiu, Mihaela [University Polytechnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061, Bucharest (Romania); Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095, Bucharest (Romania); Pirvu, Cristian [University Polytechnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061, Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095, Bucharest (Romania)

    2013-08-01

    In this study, polypyrrole (PPy) films were successfully synthesized on Ti6Al7Nb alloy by potentiostatic polymerization in the presence of poly(sodium 4-styrenesulfonate) (NaPSS), t-octylphenoxy polyethoxyethanol (Triton X-100) and N-dodecyl-β-D-maltoside (DM) surfactants. Atomic force microscopy (AFM) analysis of the PPy/surfactant composite films revealed a granular structure characterized by a lower surface roughness than un-modified PPy films. The results demonstrated that addition of surfactants, namely Triton X-100 and DM, can improve electrochemical film stability and corrosion resistance. Further, Triton X-100 enhanced the adhesive strength of PPy films to the substrate. The surfactant type also showed a great influence on the surface wettability, the highest hydrophilic character being observed in the case of PPy/PSS film. Few studies have been devoted to the elucidation of inflammatory cell response to PPy-based materials. Therefore, RAW 264.7 macrophages were cultured on PPy-surfactant films to determine whether they elicit a differential cell behavior in terms of cell adhesion, proliferation, cellular morphology and cytokine secretion. Our results highlight the dependence of macrophage response on the surfactants used in the pyrrole polymerization process and suggest that the immune response to biomaterials coated with PPy films might be controlled by the choice of surfactant molecules. Highlights: • We electrodeposited polypyrrole films on Ti6Al7Nb alloy using three surfactants. • Differences in electrostability and wettability of polypyrrole films were found. • Triton X increased and NaPSS decreased the adhesion of polypyrrole films to Ti6Al7Nb. • Cytoskeletal architecture and macrophage activation were affected by surfactants. • The hydrophilic PPy/PSS coating elicited the lowest inflammatory response.

  16. Surfactant-dependent macrophage response to polypyrrole-based coatings electrodeposited on Ti6Al7Nb alloy

    International Nuclear Information System (INIS)

    Mindroiu, Mihaela; Ion, Raluca; Pirvu, Cristian; Cimpean, Anisoara

    2013-01-01

    In this study, polypyrrole (PPy) films were successfully synthesized on Ti6Al7Nb alloy by potentiostatic polymerization in the presence of poly(sodium 4-styrenesulfonate) (NaPSS), t-octylphenoxy polyethoxyethanol (Triton X-100) and N-dodecyl-β-D-maltoside (DM) surfactants. Atomic force microscopy (AFM) analysis of the PPy/surfactant composite films revealed a granular structure characterized by a lower surface roughness than un-modified PPy films. The results demonstrated that addition of surfactants, namely Triton X-100 and DM, can improve electrochemical film stability and corrosion resistance. Further, Triton X-100 enhanced the adhesive strength of PPy films to the substrate. The surfactant type also showed a great influence on the surface wettability, the highest hydrophilic character being observed in the case of PPy/PSS film. Few studies have been devoted to the elucidation of inflammatory cell response to PPy-based materials. Therefore, RAW 264.7 macrophages were cultured on PPy-surfactant films to determine whether they elicit a differential cell behavior in terms of cell adhesion, proliferation, cellular morphology and cytokine secretion. Our results highlight the dependence of macrophage response on the surfactants used in the pyrrole polymerization process and suggest that the immune response to biomaterials coated with PPy films might be controlled by the choice of surfactant molecules. Highlights: • We electrodeposited polypyrrole films on Ti6Al7Nb alloy using three surfactants. • Differences in electrostability and wettability of polypyrrole films were found. • Triton X increased and NaPSS decreased the adhesion of polypyrrole films to Ti6Al7Nb. • Cytoskeletal architecture and macrophage activation were affected by surfactants. • The hydrophilic PPy/PSS coating elicited the lowest inflammatory response

  17. 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.

  18. Controlled Clustering in Binary Charged Colloids by Adsorption of Ionic Surfactants.

    Science.gov (United States)

    Nakamura, Yuki; Okachi, Manami; Toyotama, Akiko; Okuzono, Tohru; Yamanaka, Junpei

    2015-12-15

    We report on the controlled clustering of oppositely charged colloidal particles by the adsorption of ionic surfactants, which tunes charge numbers Z of particles. In particular, we studied the heteroclustering of submicron-sized polystyrene (PS) and silica particles, both of which are negatively charged, in the presence of cetylpyridinium chloride (CPC), a cationic surfactant. The surfactant concentration Csurf was selected below the critical micelle concentration. As CPC molecules were adsorbed, Z values of the PS and silica particles decreased, inverting to positive when Csurf exceeded the isoelectric point Ciep. Hydrophobic PS particles exhibited much lower Ciep than hydrophilic silica particles. At Csurf valuess between their Ciep values, the particles were oppositely charged, and clustering was enabled. To explain the clustering behavior, we investigated adsorption isotherms of the CPC and screened-Coulomb-type pair potential. Expected applications of the present findings are the control of colloidal associations and construction of various particle types into heterogeneous colloidal clusters.

  19. A novel explanation for the enhanced colloidal stability of silver nanoparticles in the presence of an oppositely charged surfactant.

    Science.gov (United States)

    Skoglund, Sara; Blomberg, Eva; Wallinder, Inger Odnevall; Grillo, Isabelle; Pedersen, Jan Skov; Bergström, L Magnus

    2017-10-25

    The structural behavior in aqueous mixtures of negatively charged silver nanoparticles (Ag NPs) together with the cationic surfactants cetyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium chloride (DTAC), respectively, has been investigated using SANS and SAXS. From our SANS data analysis we are able to conclude that the surfactants self-assemble into micellar clusters surrounding the Ag NPs. We are able to quantify our results by means of fitting experimental SANS data with a model based on cluster formation of micelles with very good agreement. Based on our experimental results, we propose a novel mechanism for the stabilization of negatively charged Ag NPs in a solution of positively charged surfactants in which cluster formation of micelles in the vicinity of the particles prevents the particles from aggregating. Complementary SAXS and DLS measurements further support this novel way of explaining stabilization of small hydrophilic nanoparticles in surfactant-containing solutions.

  20. Soil Water Retention Curve

    Science.gov (United States)

    Johnson, L. E.; Kim, J.; Cifelli, R.; Chandra, C. V.

    2016-12-01

    Potential water retention, S, is one of parameters commonly used in hydrologic modeling for soil moisture accounting. Physically, S indicates total amount of water which can be stored in soil and is expressed in units of depth. S can be represented as a change of soil moisture content and in this context is commonly used to estimate direct runoff, especially in the Soil Conservation Service (SCS) curve number (CN) method. Generally, the lumped and the distributed hydrologic models can easily use the SCS-CN method to estimate direct runoff. Changes in potential water retention have been used in previous SCS-CN studies; however, these studies have focused on long-term hydrologic simulations where S is allowed to vary at the daily time scale. While useful for hydrologic events that span multiple days, the resolution is too coarse for short-term applications such as flash flood events where S may not recover its full potential. In this study, a new method for estimating a time-variable potential water retention at hourly time-scales is presented. The methodology is applied for the Napa River basin, California. The streamflow gage at St Helena, located in the upper reaches of the basin, is used as the control gage site to evaluate the model performance as it is has minimal influences by reservoirs and diversions. Rainfall events from 2011 to 2012 are used for estimating the event-based SCS CN to transfer to S. As a result, we have derived the potential water retention curve and it is classified into three sections depending on the relative change in S. The first is a negative slope section arising from the difference in the rate of moving water through the soil column, the second is a zero change section representing the initial recovery the potential water retention, and the third is a positive change section representing the full recovery of the potential water retention. Also, we found that the soil water moving has traffic jam within 24 hours after finished first

  1. Nonlinear dynamics in experimental devices with compressed/expanded surfactant monolayers

    International Nuclear Information System (INIS)

    Higuera, M; Perales, J M; Vega, J M

    2014-01-01

    A theory is provided for a common experimental set up that is used to measure surface properties in surfactant monolayers. The set up consists of a surfactant monolayer (over a shallow liquid layer) that is compressed/expanded in a periodic fashion by moving in counter-phase two parallel, slightly immersed solid barriers, which vary the free surface area and thus the surfactant concentration. The simplest theory ignores the fluid dynamics in the bulk fluid, assuming spatially uniform surfactant concentration, which requires quite small forcing frequencies and provides reversible dynamics in the compression/expansion cycles. In this paper, we present a long-wave theory for not so slow oscillations that assumes local equilibrium but takes the fluid dynamics into account. This simple theory uncovers the physical mechanisms involved in the surfactant behavior and allows for extracting more information from each experimental run. The conclusion is that the fluid dynamics cannot be ignored, and that some irreversible dynamics could well have a fluid dynamic origin. (paper)

  2. Effects of radiation and temperature on iodide sorption by surfactant-modified bentonite.

    Science.gov (United States)

    Choung, Sungwook; Kim, Minkyung; Yang, Jung-Seok; Kim, Min-Gyu; Um, Wooyong

    2014-08-19

    Bentonite, which is used as an engineered barrier in geological repositories, is ineffective for sorbing anionic radionuclides because of its negatively charged surface. This study modified raw bentonite using a cationic surfactant (i.e., hexadecyltrimethylammonium [HDTMA]-Br) to improve its sorption capability for radioactive iodide. The effects of temperature and radiation on the iodide sorption of surfactant-modified bentonite (SMB) were also evaluated under alkaline pH condition similar to that found in repository environments. Different amounts of surfactant, equivalent to the 50, 100, and 200% cation-exchange capacity of the bentonite, were used to produce the HDTMA-SMB for iodide sorption. The sorption reaction of the SMB with iodide reached equilibrium rapidly within 10 min regardless of temperature and radiation conditions. The rate of iodide sorption increased as the amount of the added surfactant was increased and nonlinear sorption behavior was exhibited. However, high temperature and γ-irradiation ((60)Co) resulted in significantly (∼2-10 times) lower iodide Kd values for the SMB. The results of FTIR, NMR, and XANES spectroscopy analysis suggested that the decrease in iodide sorption may be caused by weakened physical electrostatic force between the HDTMA and iodide, and by the surfactant becoming detached from the SMB during the heating and irradiation processes.

  3. Magnetically Alignable Bicelles with Unprecedented Stability Using Tunable Surfactants Derived from Cholic Acid.

    Science.gov (United States)

    Matsui, Ryoichi; Uchida, Noriyuki; Ohtani, Masataka; Yamada, Kuniyo; Shigeta, Arisu; Kawamura, Izuru; Aida, Takuzo; Ishida, Yasuhiro

    2016-12-05

    Five novel surfactants were prepared by modifying the three hydroxy groups of sodium cholate with triethylene glycol chains endcapped with an amide (SC-C 1 , SC- n C 4 , and SC- n C 5 ) or a carbamoyl group (SC-O n C 4 and SC-O t C 4 ). The phase behavior of aqueous mixtures of these surfactants with 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) was systematically studied by 31 P NMR spectroscopy. The surfactants endcapped with carbamate groups (SC-O n C 4 and SC-O t C 4 ) formed magnetically alignable bicelles over unprecedentedly wide ranges of conditions, in terms of temperature (from 21-23 to >90 °C), lipid/surfactant ratio (from 5 to 8), total lipid content (5-20 wt %), and lipid type [DMPC, 1,2-dilauroyl-sn-glycero-3-phosphatidylcholine (DLPC), or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC)]. In conjunction with appropriate phospholipids, the carbamate-endcapped surfactants afforded unique bicelles, characterized by exceptional thermal stabilities (from 0 to >90 °C), biomimetic lipid compositions (DMPC/POPC=25:75 to 50:50), and extremely large 2 H quadrupole splittings (up to 71 Hz). © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Design of Agglomerated Crystals of Ibuprofen During Crystallization: Influence of Surfactant

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2011-01-01

    Full Text Available Objective(sIbuprofen is a problematic drug in tableting, and dissolution due to its poor solubility, hydrophobicity, and tendency to stick to surface. Because of the bad compaction behavior ibuprofen has to be granulated usually before tableting. However, it would be more satisfactory to obtain directly during the crystallization step crystalline particles that can be directly compressed and quickly dissolved. Materials and Methods Crystallization of ibuprofen was carried out using the quasi emulsion solvent diffusion method in presence of surfactant (sodium lauryl sulfate (SLS, Tween 80. The particles were characterized by differential scanning calorimetry (DSC, powder X-ray diffraction (XRPD and were evaluated for particle size, flowability, drug release and tableting behavior. ResultsIbuprofen particles obtained in the presence of surfactants consisted of numerous plate- shaped crystals which had agglomerated together as near spherical shape. The obtained agglomerates exhibited significantly improved micromeritic properties as well as tableting behavior than untreated drug crystals. The agglomerates size and size distribution was largely controlled by surfactant concentration, but there was no significant influence found on the tableting properties. The dissolution tests showed that the agglomerates obtained in presence of SLS exhibited enhanced dissolution rate while the agglomerates made in the presence of Tween 80 had no significant impact on dissolution rate of ibuprofen in comparison to untreated sample. The XRPD and DSC results showed that during the agglomeration process, ibuprofen did not undergo any polymorphic changes.Conclusion The study highlights the influence of surfactants on crystallization process leading to modified performance.

  5. Interactions of organic contaminants with mineral-adsorbed surfactants

    Science.gov (United States)

    Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

    2003-01-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  6. Enhancing retention of partial dentures using elastomeric retention rings

    Directory of Open Access Journals (Sweden)

    Kakkirala Revathi

    2015-01-01

    Full Text Available This report presents an alternative method for the retention of partial dentures that relies on the engagement of tooth undercuts by a lining material. The lab procedures are also presented. A new maxillary and mandibular acrylic partial dentures were fabricated using elastomeric retention technique for a partially dentate patient. A partially dentate man reported difficulty in retaining his upper removable partial denture (RPD. The maxillary RPD was designed utilizing elastomeric retention technique. During follow-up, it was necessary to replace the retention rings due to wear. The replacement of the retention rings, in this case, was done through a chairside reline technique. Elastomeric retention technique provides exceptionally good retention can be indicated to stabilize, cushion, splint periodontally involved teeth, no enough undercut for clasps, eliminate extractions, single or isolated teeth.

  7. Characterization and stability of catanionic vesicles formed by pseudo-tetraalkyl surfactant mixtures.

    Science.gov (United States)

    Pucci, Carlotta; Pérez, Lourdes; La Mesa, Camillo; Pons, Ramon

    2014-12-28

    The phase behavior of an ad hoc synthesized surfactant, sodium 8-hexadecylsulfate (8-SHS), and its mixtures with didecyldimethylammonium bromide (DiDAB) in water is reported. We dealt with dilute concentration regimes, at a total surfactant content of <30 mmol kg(-1) where vesicular aggregates may be formed. The high synergistic behavior of such catanionic mixtures is concomitant with strongly negative interaction parameters, β (≈-18 kBT), significant gain in the free energy of association, ΔGagg, and much lower association concentration compared to the pure surfactants. Vesicle size and ζ-potential depend on the mixture composition. Hydrodynamic diameters increase by progressive addition of oppositely charged surfactants to the one in excess. Counter-intuitively, the ζ-potential becomes more negative at DiDAB molar fractions close to 0.2. The same holds in the reverse case, the ζ-potential becomes more positive after small additions of 8-SHS; anyhow, the effect is more significant in anionic-rich mixtures. This phenomenon was explained by assuming a significant release of counterions and an asymmetric distribution of the two surfactants in the inner and outer vesicle leaflets. The equimolar mixtures form a cubic phase rather than the expected lamellar one. The effect of NaBr concentration on the stability of catanionic vesicles was also investigated. At high NaBr concentrations, all systems are destabilized. For DiDAB-rich vesicles, flocculation is observed, while for 8-SHS-rich ones, lamellar domains are formed at the bottom of the samples. The role played by NaBr depends on whether it is added before or after mixing the surfactants. In particular, preformed catanionic vesicles show a great kinetic stability towards addition of NaBr compared to those obtained by other procedures.

  8. Effect of Surfactants on the Deformation and Detachment of Oil Droplets in a Model Laminar Flow Cell

    Directory of Open Access Journals (Sweden)

    Fréville V.

    2013-10-01

    Full Text Available Sugar-based surfactants are increasingly present in the development of eco-friendly detergents due to current regulations and consumer demand. In order to assess the degreasing performance of these new surfactants, the behavior of model oil droplets subjected to the action of a flow of surfactant solutions of different concentrations was studied in a laminar flow cell and related to the physico-chemical properties measured at the liquid/liquid (interfacial tension and solid/liquid/liquid interfaces (contact angle. With the surfactant solutions and the model oils employed in this study, three main behaviors were observed when a critical flow rate was reached: elongation, fragmentation or spontaneous detachment of the droplet. The analysis of the results leads to a correlation between the droplet behavior and the balance of the forces applied on the droplet in its initial position, in particular the gravity force Fg, which tends to move the oil droplet upwards (given the density difference, and the capillary force Fc, which tends to keep the droplet spherical. A state diagram could be established, based on the dimensionless Bond number (Fg/Fc and cosθ, θ being the initial contact angle of the drop on the surface before the establishment of the flow. One can thus predict the droplet behavior as a function of the system initial characteristics. The results allowed the comparison of degreasing performance of the different surfactants used and illustrated the potential of AlkylPolyPentosides (APP for detergent formulations.

  9. Surfactant nebulization versus instillation during high frequency ventilation in surfactant-deficient rabbits

    NARCIS (Netherlands)

    Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

    1998-01-01

    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

  10. Size control of surfactant vesicles made by a mixture of cationic surfactants and organic derivatives.

    Science.gov (United States)

    Kim, Tae-Hwan; Han, Young-Soo; Jang, Jong-Dae; Seong, Baek-Seok

    2014-10-01

    Spontaneous size-controllable vesicles that are prepared by a mixture of surfactants with different alkyl chain lengths (n-alkyltrimethylammonium bromide, C(n)TAB) and an organic derivative (5-methyl salicylic acid, 5mS) in aqueous solution have been investigated. When the organic derivative 5mS is mixed with the C(n)TAB surfactants in aqueous solution, the surfactant vesicles are spontaneously formed above a certain 5mS concentration. Small angle neutron scattering reveals that the core radius of surfactant vesicles is clearly increased from ca. 31 nm to ca. 97 nm with the alkyl chain length of surfactants while the bilayer thickness of the vesicles is nearly constant. The structure of surfactant vesicles maintains against temperature change ranging from 30 degrees C to 45 degrees C, showing no structural change. These results can provide thermally stable surfactant vesicles with various sizes and constant bilayer thickness that may possess a different permeability and may allow the surfactant vesicle to be used in gene or drug delivery for a variety of goods.

  11. Surfactant Delivery into the Lung

    Science.gov (United States)

    Grotberg, James; Filoche, Marcel

    2014-11-01

    We have developed a multiscale, compartmentalized model of surfactant and liquid delivery into the lung. Assuming liquid plug propagation, the airway compartment accounts for the plug's volume deposition (coating) on the airway wall, while the bifurcation compartment accounts for plug splitting from the parent airway to the two daughter airways. Generally the split is unequal due to gravity and geometry effects. Both the deposition ratio RD (deposition volume/airway volume), and the splitting ratio, RS, of the daughters volumes are solved independently from one another. Then they are used in a 3D airway network geometry to achieve the distribution of delivery into the lung. The airway geometry is selected for neonatal as well as adult applications, and can be advanced from symmetric, to stochastically asymmetric, to personalized. RD depends primarily on the capillary number, Ca, while RS depends on Ca, the Reynolds number, Re, the Bond number, Bo, the dose volume, VD, and the branch angles. The model predicts the distribution of coating on the airway walls and the remaining plug volume delivered to the alveolar region at the end of the tree. Using this model, we are able to simulate and test various delivery protocols, in order to optimize delivery and improve the respiratory function.

  12. 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

  13. Role of linker groups between hydrophilic and hydrophobic moieties of cationic surfactants on oligonucleotide-surfactant interactions.

    Science.gov (United States)

    Santhiya, Deenan; Dias, Rita S; Shome, Anshupriya; Das, Prasanta Kumar; Miguel, Maria G; Lindman, Björn; Maiti, Souvik

    2009-12-15

    The interaction between DNA and amino-acid-based surfactants with different linker groups was investigated by gel electrophoresis, ethidium bromide exclusion assays, circular dichroism, and melting temperature determinations. The studies showed that the strength of the interaction between the oligonucleotides and the surfactants is highly dependent on the linker of the surfactant. For ester surfactants, no significant interaction was observed for surfactant-to-DNA charge ratios up to 12. On the other hand, amide surfactants were shown to interact strongly with the oligonucleotides; these surfactants could displace up to 75% of the ethidium bromide molecules bound to the DNA and induced significant changes in the circular dichroism spectra. When comparing the headgroups of the surfactants, it was observed that surfactants with more hydrophobic headgroups (proline vs alanine) interacted more strongly with the DNA, in good agreement with previous studies.

  14. The effects of alkylammonium counterions on the aggregation of fluorinated surfactants and surfactant ionic liquids.

    Science.gov (United States)

    Pottage, Matthew J; Greaves, Tamar L; Garvey, Christopher J; Tabor, Rico F

    2016-08-01

    The effects of organic counterions with varying carbon number on surfactant aggregation have been analysed by coupling perfluorooctanoate surfactant anions with various alkylammonium counterions. Both the degree of substitution (primary to tertiary) and alkyl chain length (0-3 carbons) of the counterions were varied to provide a comprehensive matrix of geometries and lipophilicities. Surface activity was measured using pendant drop tensiometry, while temperature-controlled small-angle neutron scattering was used to probe changes in aggregation morphology. It was found that the use of such alkylammonium counterions resulted in a strong preference for bilayer formation even at low surfactant concentration (surfactant-rich lamellar phase coexists with a dilute micellar phase. The results indicate that aggregation is controlled by a delicate balance of counterion size, hydrophilicity and diffuseness of charge, providing new methods for the subtle control of surfactant solutions. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  15. Redox-induced ion pairing of anionic surfactants with ferrocene-terminated self-assembled monolayers: Faradaic electrochemistry and surfactant aggregation at the monolayer/liquid interface.

    Science.gov (United States)

    Dionne, Eric R; Sultana, Tania; Norman, Lana L; Toader, Violeta; Badia, Antonella

    2013-11-20

    Oxidoreduction of self-assembled monolayers (SAMs) of ferrocenyldodecanethiolate on gold in aqueous solutions of surface-active sodium n-alkyl sulfates (NaCnSO4) of 6, 8, 10, and 12 carbons is investigated by cyclic voltammetry and surface plasmon resonance. The effects of surfactant micellization and alkyl chain length on the redox response of the surface-tethered ferrocenes are examined. The SAM redox electrochemistry is sensitive to the surfactant aggregation state in solution. The nonideal behavior of the sodium alkyl sulfates at concentrations above the critical micelle concentration leads to a non-Nernstian variation of the SAM redox potential with concentration. The presence of micelles in solution results in decreased anodic-to-cathodic peak separations and anodic peak full widths at half-maximum. A longer alkyl chain length results in an increased ability of the alkyl sulfate anion to ion pair with the SAM-bound ferrocenium, resulting in oxidation of the ferrocene at lower potential. A comparison of the SAM redox potential at a fixed surfactant concentration of ideal behavior suggests a 4.5 × 10(4) difference in the ion-pairing abilities of the shorter-chain C6SO4(-) and longer-chain C12SO4(-). One-half of the available SAM-bound ferrocenes are oxidized in the NaCnSO4 electrolyte. Surfactant anions adsorb and assemble onto the SAM surface by specific ion-pairing interactions between the sulfate headgroups and oxidized ferrocenium species, forming an interdigitated monolayer in which the surfactant anions alternate between a heads-down and heads-up orientation with respect to the SAM. The work presented points to applications of ferrocenylalkanethiolate SAMs as anion-selective membranes, probes of micelle formation, and surfaces for the electrochemically switchable assembly of organosulfates.

  16. Surfactants and the Mechanics of Respiration

    Science.gov (United States)

    Jbaily, Abdulrahman; Szeri, Andrew J.

    2016-11-01

    Alveoli are small sacs found at the end of terminal bronchioles in human lungs with a mean diameter of 200 μm. A thin layer of fluid (hypophase) coats the inner face of an alveolus and is in contact with the air in the lungs. The thickness of this layer varies among alveoli, but is in the range of 0.1 to 0.5 μm for many portions of the alveolar network. The interfacial tension σ at the air-hypophase interface tends to favor collapse of the alveolus, and resists its expansion during inhalation. Type II alveolar cells synthesize and secrete a mixture of phospholipids and proteins called pulmonary surfactant. These surfactant molecules adsorb to the interface causing σ of water at body temperature is 70 mN/m and falls to an equilibrium value of 25 mN/m when surfactants are present. Also, in a dynamic sense, it is known that σ is reduced to near 0 during exhalation when the surfactant film compresses. In this work, the authors develop a mechanical and transport model of the alveolus to study the effect of surfactants on various aspects of respiration. The model is composed of three principal parts: (i) air movement into and out of the alveolus; (ii) a balance of linear momentum across the two-layered membrane of the alveolus (hypophase and elastic wall); and (iii) a pulmonary surfactant transport problem in the hypophase. The goal is to evaluate the influence of pulmonary surfactant on respiratory mechanics.

  17. Isolation of surfactant-resistant bacteria from natural, surfactant-rich marine habitats.

    Science.gov (United States)

    Plante, Craig J; Coe, Kieran M; Plante, Rebecca G

    2008-08-01

    Environmental remediation efforts often utilize either biodegradative microbes or surfactants, but not in combination. Coupling both strategies holds the potential to dramatically increase the rate and extent of remediation because surfactants can enhance the bioavailability of contaminants to microbes. However, many surfactants permeabilize bacterial cell membranes and are effective disinfectants. An important goal then is to find or genetically modify microorganisms that possess both desirable degradative capabilities and the ability to thrive in the presence of surfactants. The guts of some marine invertebrates, particularly deposit feeders, have previously been shown to contain high levels of biosurfactants. Our primary aim was to mine these natural, surfactant-rich habitats for surfactant-resistant bacteria. Relative to sediment porewaters, the gut contents of two polychaete deposit feeders, Nereis succinea and Amphitrite ornata, exhibited a significantly higher ratio of bacteria resistant to both cationic and anionic surfactants. In contrast, bacteria in the gut fluids of a holothuroid, Leptosynapta tenuis, showed surfactant susceptibility similar to that of bacteria from sediments. Analyses of 16S rRNA gene sequences revealed that the majority of surfactant-resistant isolates were previously undescribed species of the genus Vibrio or were of a group most closely related to Spongiobacter spp. We also tested a subset of resistant bacteria for the production of biosurfactants. The majority did produce biosurfactants, as demonstrated via the oil-spreading method, but in all cases, production was relatively weak under the culture conditions employed. Novel surfactant-resistant, biosurfactant-producing bacteria, and the habitats from which they were isolated, provide a new source pool for potential microorganisms to be exploited in the in situ bioremediation of marine sediments.

  18. Isolation of Surfactant-Resistant Bacteria from Natural, Surfactant-Rich Marine Habitats▿

    Science.gov (United States)

    Plante, Craig J.; Coe, Kieran M.; Plante, Rebecca G.

    2008-01-01

    Environmental remediation efforts often utilize either biodegradative microbes or surfactants, but not in combination. Coupling both strategies holds the potential to dramatically increase the rate and extent of remediation because surfactants can enhance the bioavailability of contaminants to microbes. However, many surfactants permeabilize bacterial cell membranes and are effective disinfectants. An important goal then is to find or genetically modify microorganisms that possess both desirable degradative capabilities and the ability to thrive in the presence of surfactants. The guts of some marine invertebrates, particularly deposit feeders, have previously been shown to contain high levels of biosurfactants. Our primary aim was to mine these natural, surfactant-rich habitats for surfactant-resistant bacteria. Relative to sediment porewaters, the gut contents of two polychaete deposit feeders, Nereis succinea and Amphitrite ornata, exhibited a significantly higher ratio of bacteria resistant to both cationic and anionic surfactants. In contrast, bacteria in the gut fluids of a holothuroid, Leptosynapta tenuis, showed surfactant susceptibility similar to that of bacteria from sediments. Analyses of 16S rRNA gene sequences revealed that the majority of surfactant-resistant isolates were previously undescribed species of the genus Vibrio or were of a group most closely related to Spongiobacter spp. We also tested a subset of resistant bacteria for the production of biosurfactants. The majority did produce biosurfactants, as demonstrated via the oil-spreading method, but in all cases, production was relatively weak under the culture conditions employed. Novel surfactant-resistant, biosurfactant-producing bacteria, and the habitats from which they were isolated, provide a new source pool for potential microorganisms to be exploited in the in situ bioremediation of marine sediments. PMID:18586977

  19. Behaviorism

    Science.gov (United States)

    Moore, J.

    2011-01-01

    Early forms of psychology assumed that mental life was the appropriate subject matter for psychology, and introspection was an appropriate method to engage that subject matter. In 1913, John B. Watson proposed an alternative: classical S-R behaviorism. According to Watson, behavior was a subject matter in its own right, to be studied by the…

  20. Behavior

    NARCIS (Netherlands)

    Bouwman, L.I.

    2014-01-01

    Health behaviors are people’s actions, some purposefully deployed to promote or protect health; some thoughtlessly undertaken without concern for their potential risk to health; some consciously, even defiantly, deployed regardless of consequences to health. Risk behaviors are specific forms of

  1. Surface active complexes formed between keratin polypeptides and ionic surfactants.

    Science.gov (United States)

    Pan, Fang; Lu, Zhiming; Tucker, Ian; Hosking, Sarah; Petkov, Jordan; Lu, Jian R

    2016-12-15

    Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C 12 TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes. Copyright © 2016. Published by Elsevier Inc.

  2. 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.

  3. 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

  4. Surface shear inviscidity of soluble surfactants.

    Science.gov (United States)

    Zell, Zachary A; Nowbahar, Arash; Mansard, Vincent; Leal, L Gary; Deshmukh, Suraj S; Mecca, Jodi M; Tucker, Christopher J; Squires, Todd M

    2014-03-11

    Foam and emulsion stability has long been believed to correlate with the surface shear viscosity of the surfactant used to stabilize them. Many subtleties arise in interpreting surface shear viscosity measurements, however, and correlations do not necessarily indicate causation. Using a sensitive technique designed to excite purely surface shear deformations, we make the most sensitive and precise measurements to date of the surface shear viscosity of a variety of soluble surfactants, focusing on SDS in particular. Our measurements reveal the surface shear viscosity of SDS to be below the sensitivity limit of our technique, giving an upper bound of order 0.01 μN·s/m. This conflicts directly with almost all previous studies, which reported values up to 10(3)-10(4) times higher. Multiple control and complementary measurements confirm this result, including direct visualization of monolayer deformation, for SDS and a wide variety of soluble polymeric, ionic, and nonionic surfactants of high- and low-foaming character. No soluble, small-molecule surfactant was found to have a measurable surface shear viscosity, which seriously undermines most support for any correlation between foam stability and surface shear rheology of soluble surfactants.

  5. 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

  6. 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

  7. Syntheses of surfactants from oleochemical epoxides

    Directory of Open Access Journals (Sweden)

    Warwel Siegfried

    2001-01-01

    Full Text Available Sugar-based surfactants were obtained in good yields (up to 100% under mild conditions (70°C, methanol or mixtures of methanol and water by ring-opening of terminal epoxides with aminopolyols, derived from glucose. Reaction of N-methyl glucamine with epoxides from even-numbered C4-C18 alpha-olefins or from terminal unsaturated fatty acid methyl esters leads to linear products, while corresponding reactions with N-dodecyl glucamine or glucamine yield surfactants with different Y-structures. Products obtained by conversion of omega-epoxy fatty acid methyl esters were saponificated with NaOH or hydrolyzed enzymatically to sodium salts or free acids respectively, which are amphoteric surfactants. Studies of the surfactants at different pH-values demonstrate different surface active properties in aqueous solutions. Critical micelle concentrations (c.m.c. in a range between 2 and 500mg/l and surface tensions of 25-40mN/m were measured for several of the synthesized sugar-based surfactants. The ring-opening products are rather poor foamers, whereas some of the corresponding hydrobromides show good foaming properties.

  8. Probing nanoparticle effect in protein-surfactant complexes

    Science.gov (United States)

    Mehan, Sumit; Aswal, V. K.; Kohlbrecher, J.

    2015-06-01

    SANS experiments have been carried to probe the role of anionic silica nanoparticles in the anionic BSA protein-cationic DTAB surfactant complexes. In protein-surfactant complex, surfactant molecules aggregate to form micelle-like clusters along the unfolded polypeptide chains of the protein. The nanoparticle aggregation mediated by oppositely charged protein-surfactant complex coexists with the free protein-surfactant complexes in the nanoparticle-protein-surfactant system. There is rearrangement of micelles in adsorbed protein-surfactant complex on nanoparticles in leading to their (nanoparticle) aggregation. On the other hand, the unfolding of protein in free protein-surfactant complex is found to be significantly enhanced in presence of nanoparticles.

  9. 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...

  10. 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.

  11. Enhanced perfume surface delivery to interfaces using surfactant surface multilayer structures.

    Science.gov (United States)

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

    2016-01-01

    Enhanced surface delivery and retention of perfumes at interfaces are the keys to their more effective and efficient deployment in a wide range of home and personal care related formulations. It has been previously demonstrated that the addition of multivalent counterions, notably Ca(2+), induces multilayer adsorption at the air-water interface for the anionic surfactant, sodium dodecyl-6-benzenesulfonate, LAS-6. Neutron reflectivity, NR, measurements are reported here which demonstrate that such surfactant surface multilayer structures are a potentially promising vehicle for enhanced delivery of perfumes to interfaces. The data show that the incorporation of the model perfumes, phenylethanol, PE, and linalool, LL, into the surface multilayer structure formed by LAS-6/Ca(2+) results in the surface structures being retained up to relatively high perfume mole fractions. Furthermore the amount of perfume at the surface is enhanced by at least an order of magnitude, compared to that co-adsorbed with a surfactant monolayer. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Neo-Geometric Copper Nanocrystals by Competitive, Dual Surfactant-Mediated Facet Adsorption Controlling Skin Permeation

    Directory of Open Access Journals (Sweden)

    Karmani Murugan

    2016-11-01

    Full Text Available Neogeometric copper nanoparticles (CuNPs have various applications yet its synthesis still proves to be challenging with regards to self-assembly and uniformity control. This study aimed to synthesize shape-specific CuNPs in the biomedical application of ascertaining skin permeation and retention of the CuNPs as a drug delivery system. The approach to the shape design involved the dual control of two surfactants to direct the shape organisation of the nanoparticles (NPs while an interesting aspect of the study showed the competitive adsorption of the surfactants onto the nanocrystal facets to direct facet growth. The resulting copper nanoparticles were characterised using X-ray diffraction (XRD and electron diffraction spectra analysis (EDS for elemental and crystalline analysis. Thermogravimetric Analysis (TGA identified the degradation of the surfactant coat and the synthesis of a novel copper-polymer complex and extensive transmission electron microscopy (TEM was conducted to determine the nanoparticle morphology. Epidermal skin tissue served as the model for permeation studies of five idealistic nano-geometries and investigated its application in drug delivery with regards to cellular internalisation and transbarrier transport of the geometric CuNPs. A mechanistic consideration for shape control is discussed.

  13. Humidity-Induced Phase Transitions of Surfactants Embedded in Latex Coatings Can Drastically Alter Their Water Barrier and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Juan F. Gonzalez-Martinez

    2018-03-01

    Full Text Available Latex coatings are environmentally friendly i.e., they are formed from aqueous polymer dispersions, are cheap to produce and provide exceptional mechanical properties. Therefore, they are ubiquitous and can be found in a wide range of different applications such as paints and varnishes, pressure-sensitive adhesives, textiles, construction materials, paper coatings and inks. However, they also have weaknesses and their surfactant content is among them. Surfactants are often needed to stabilize polymer particles in the aqueous latex dispersions. These surfactants also form part of the coatings formed from these dispersions, and it is well-known that they can lower their performance. This work further explores this aspect and focuses on the role that embedded surfactant domains play in the response of latex coatings to humid environments. For this purpose, we made use of several experimental techniques where humidity control was implemented: quartz crystal microbalance with dissipation, atomic force microscopy and differential scanning calorimetry. By means of this multimethodological approach, we report that surfactants embedded in latex coatings can undergo humidity-induced transitions towards more hydrated and softer phases, and that this results in a drastic decrease of the mechanical and water barrier properties of the whole coatings. Subsequently, this work highlights the potential of taking into account the phase behavior of surfactants when choosing which ones to use in the synthesis of latex dispersions as this would help in predicting their performance under different environmental conditions.

  14. Recent food applications of microbial surfactants.

    Science.gov (United States)

    Nitschke, Marcia; Silva, Sumária Sousa E

    2016-07-20

    Owing to their natural origin and environmental compatibility, interest in microbial surfactants or biosurfactants has gained attention during last few years. These characteristics fulfill the demand of regulatory agencies and society to use more sustained and green chemicals. Microbial-derived surfactants can replace synthetic surfactants in a great variety of industrial applications as detergents, foaming, emulsifiers, solubilizers, and wetting agents. Change in the trend of consumers toward natural from synthetic additives and the increasing health and environmental concerns have created demand for new "green" additives in foods. Apart from their inherent surface-active properties, biosurfactants have shown antimicrobial and anti-biofilm activities against food pathogens; therefore, biosurfactants can be versatile additives or ingredients of food processing. These interesting applications will be discussed in this review.

  15. 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.

  16. Nanotube Dispersions Made With Charged Surfactant

    Science.gov (United States)

    Kuper, Cynthia; Kuzma, Mike

    2006-01-01

    Dispersions (including monodispersions) of nanotubes in water at relatively high concentrations have been formulated as prototypes of reagents for use in making fibers, films, and membranes based on single-walled carbon nanotubes (SWNTs). Other than water, the ingredients of a dispersion of this type include one or more charged surfactant(s) and carbon nanotubes derived from the HiPco(TradeMark) (or equivalent) process. Among reagents known to be made from HiPco(TradeMark)(or equivalent) SWNTs, these are the most concentrated and are expected to be usable in processing of bulk structures and materials. Test data indicate that small bundles of SWNTs and single SWNTs at concentrations up to 1.1 weight percent have been present in water plus surfactant. This development is expected to contribute to the growth of an industry based on applied carbon nanotechnology. There are expected to be commercial applications in aerospace, avionics, sporting goods, automotive products, biotechnology, and medicine.

  17. Surfactant studies for bench-scale operation

    Science.gov (United States)

    Hickey, Gregory S.; Sharma, Pramod K.

    1993-01-01

    A phase 2 study has been initiated to investigate surfactant-assisted coal liquefaction, with the objective of quantifying the enhancement in liquid yields and product quality. This report covers the second quarter of work. The major accomplishments were: completion of coal liquefaction autoclave reactor runs with Illinois number 6 coal at processing temperatures of 300, 325, and 350 C, and pressures of 1800 psig; analysis of the filter cake and the filtrate obtained from the treated slurry in each run; and correlation of the coal conversions and the liquid yield quality to the surfactant concentration. An increase in coal conversions and upgrading of the liquid product quality due to surfactant addition was observed for all runs.

  18. Brine-resistant sulfonate surfactants for enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Stournas, S.

    1983-01-01

    One of the most severe limitations of surfactant waterflooding is the instability of the commonly employed surfactants in the usual ionic environments of oil reservoirs. A specific modification to the usual structure of sulfonate surfactants not only makes them immune to high concentrations of monovalent and divalent cations, but also enables them to act as stabilizer of the common surfactants and to displace tertiary oil in brines of high salinity and divalent ion content.

  19. A Review on Progress in QSPR Studies for Surfactants

    OpenAIRE

    Zhengwu Wang; Xiaoyi Zhang; Jiwei Hu

    2010-01-01

    This paper presents a review on recent progress in quantitative structure-property relationship (QSPR) studies of surfactants and applications of various molecular descriptors. QSPR studies on critical micelle concentration (cmc) and surface tension (γ) of surfactants are introduced. Studies on charge distribution in ionic surfactants by quantum chemical calculations and its effects on the structures and properties of the colloids of surfactants are also reviewed. The trends of QSPR studies o...

  20. Xylem Surfactants Introduce a New Element to the Cohesion-Tension Theory1[OPEN

    Science.gov (United States)

    Espino, Susana; Nima, Neda; Do, Aissa Y.T.; Michaud, Joseph M.; Papahadjopoulos-Sternberg, Brigitte; Yang, Jinlong; Steppe, Kathy

    2017-01-01

    Vascular plants transport water under negative pressure without constantly creating gas bubbles that would disable their hydraulic systems. Attempts to replicate this feat in artificial systems almost invariably result in bubble formation, except under highly controlled conditions with pure water and only hydrophilic surfaces present. In theory, conditions in the xylem should favor bubble nucleation even more: there are millions of conduits with at least some hydrophobic surfaces, and xylem sap is saturated or sometimes supersaturated with atmospheric gas and may contain surface-active molecules that can lower surface tension. So how do plants transport water under negative pressure? Here, we show that angiosperm xylem contains abundant hydrophobic surfaces as well as insoluble lipid surfactants, including phospholipids, and proteins, a composition similar to pulmonary surfactants. Lipid surfactants were found in xylem sap and as nanoparticles under transmission electron microscopy in pores of intervessel pit membranes and deposited on vessel wall surfaces. Nanoparticles observed in xylem sap via nanoparticle-tracking analysis included surfactant-coated nanobubbles when examined by freeze-fracture electron microscopy. Based on their fracture behavior, this technique is able to distinguish between dense-core particles, liquid-filled, bilayer-coated vesicles/liposomes, and gas-filled bubbles. Xylem surfactants showed strong surface activity that reduces surface tension to low values when concentrated as they are in pit membrane pores. We hypothesize that xylem surfactants support water transport under negative pressure as explained by the cohesion-tension theory by coating hydrophobic surfaces and nanobubbles, thereby keeping the latter below the critical size at which bubbles would expand to form embolisms. PMID:27927981

  1. Xylem Surfactants Introduce a New Element to the Cohesion-Tension Theory.

    Science.gov (United States)

    Schenk, H Jochen; Espino, Susana; Romo, David M; Nima, Neda; Do, Aissa Y T; Michaud, Joseph M; Papahadjopoulos-Sternberg, Brigitte; Yang, Jinlong; Zuo, Yi Y; Steppe, Kathy; Jansen, Steven

    2017-02-01

    Vascular plants transport water under negative pressure without constantly creating gas bubbles that would disable their hydraulic systems. Attempts to replicate this feat in artificial systems almost invariably result in bubble formation, except under highly controlled conditions with pure water and only hydrophilic surfaces present. In theory, conditions in the xylem should favor bubble nucleation even more: there are millions of conduits with at least some hydrophobic surfaces, and xylem sap is saturated or sometimes supersaturated with atmospheric gas and may contain surface-active molecules that can lower surface tension. So how do plants transport water under negative pressure? Here, we show that angiosperm xylem contains abundant hydrophobic surfaces as well as insoluble lipid surfactants, including phospholipids, and proteins, a composition similar to pulmonary surfactants. Lipid surfactants were found in xylem sap and as nanoparticles under transmission electron microscopy in pores of intervessel pit membranes and deposited on vessel wall surfaces. Nanoparticles observed in xylem sap via nanoparticle-tracking analysis included surfactant-coated nanobubbles when examined by freeze-fracture electron microscopy. Based on their fracture behavior, this technique is able to distinguish between dense-core particles, liquid-filled, bilayer-coated vesicles/liposomes, and gas-filled bubbles. Xylem surfactants showed strong surface activity that reduces surface tension to low values when concentrated as they are in pit membrane pores. We hypothesize that xylem surfactants support water transport under negative pressure as explained by the cohesion-tension theory by coating hydrophobic surfaces and nanobubbles, thereby keeping the latter below the critical size at which bubbles would expand to form embolisms. © 2017 American Society of Plant Biologists. All Rights Reserved.

  2. Rheological Properties of Silica Nanoparticles in Brine and Brine-Surfactant Systems

    Science.gov (United States)

    Pales, Ashley; Kinsey, Erin; Li, Chunyan; Mu, Linlin; Bai, Lingyun; Clifford, Heather; Darnault, Christophe

    2016-04-01

    Rheological Properties of Silica Nanoparticles in Brine and Brine-Surfactant Systems Ashley R. Pales, Erin Kinsey, Chunyan Li, Linlin Mu, Lingyun Bai, Heather Clifford, and Christophe J. G. Darnault Department of Environmental Engineering and Earth Sciences, Laboratory of Hydrogeoscience and Biological Engineering, L.G. Rich Environmental Laboratory, Clemson University, Clemson, SC, USA Nanofluids are suspensions of nanometer sized particles in any fluid base, where the nanoparticles effect the properties of the fluid base. Commonly, nanofluids are water based, however, other bases such as ethylene-glycol, glycerol, and propylene-glycol, have been researched to understand the rheological properties of the nanofluids. This work aims to understand the fundamental rheological properties of silica nanoparticles in brine based and brine-surfactant based nanofluids with temperature variations. This was done by using variable weight percent of silica nanoparticles from 0.001% to 0.1%. Five percent brine was used to create the brine based nanofluids; and 5% brine with 2CMC of Tween 20 nonionic surfactant (Sigma-Aldrich) was used to create the brine-surfactant nanofluid. Rheological behaviors, such as shear rate, shear stress, and viscosity, were compared between these nanofluids at 20C and at 60C across the varied nanoparticle wt%. The goal of this work is to provide a fundamental basis for future applied testing for enhanced oil recovery. It is hypothesized that the addition of surfactant will have a positive impact on nanofluid properties that will be useful for enhance oil recovery. Differences have been observed in preliminary data analysis of the rheological properties between these two nanofluids indicating that the surfactant is having the hypothesized effect.

  3. Novel surfactant-selective membrane electrode based on polyelectrolyte-surfactant complex.

    Science.gov (United States)

    Zorin, Ivan; Scherbinina, Tatiana; Fetin, Petr; Makarov, Ivan; Bilibin, Alexander

    2014-12-01

    Novel class of active ionophores for surfactant selective electrodes is proposed. PVC membrane doped with polyelectrolyte-surfactant stoichiometric complex is used for ion-selective electrode construction responsive to cetyltrimethyl ammonium bromide and related surfactants. New ionophore is quite stable and completely insoluble in aqueous media in wide range of pH. The electrode displays nearly Nernstian slope in CTAB concentration range 10(-6)-10(-3)M. Polyelectrolyte platform allows to design wide range of different ionophores responsive to cationic organic substances. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Recycling retention functions

    International Nuclear Information System (INIS)

    Skrable, K.W.; Chabot, G.E.; Johnson, M.H.

    1981-01-01

    Beginning with the concept of any number of physiologically meaningful compartments that recycle material with a central extracellular fluid compartment and considering various excretion pathways, we solve the differential equations describing the kinetics by the method of Laplace to obtain concise algebraic expressions for the retentions. These expressions contain both fundamental and eigenvalue rate constants; the eigenvalue rate constants are obtained from the solution of a polynomial incorporating the fundamental rate constants. Mathematically exact expressions that predict the biodistribution resulting from continuous uptakes are used to obtain very simple mathematically exact steady state expressions as well as approximate expressions applicable to any time. These steady state and approximate expressions contain only the fundamental rate constants; also, they include a recycling factor that describes the increase in the biodistributions because of recycling. To obtain the values of the fundamental rate constants, short term kinetics studies along with data on the long term distributions are suggested. Retention functions obtained in this way predict both the short term and long term distributions; they therefore are useful in the interpretation of bioassay data and in the estimation of internal doses

  5. 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

  6. INTERACTIONS BETWEEN WATER-SOLUBLE NONIONIC POLYMERS AND SURFACTANT AGGREGATES

    NARCIS (Netherlands)

    BRACKMAN, JC; ENGBERTS, JBFN; Herb, CA; Prudhomme, RK

    1994-01-01

    The influence of the chemical structure and charge of the surfactant on polymer-micelle interaction has been studied using various ionic and non-ionic surfactants, and surfactants of which the charge can be varied by (de)protonation. Octylthioglucoside, dodecyldimethylamine-oxide, alkylphosphates,

  7. Phenanthrene partitioning in sediment-surfactant-fresh/saline water systems

    International Nuclear Information System (INIS)

    Sun Hongwen; Wu Wenling; Wang Lei

    2009-01-01

    The objective of this study was to investigate the influence of salinity on the effectiveness of surfactants in the remediation of sediments contaminated with phenanthrene (PHE). This is an example of a more general application of surfactants in removing hydrophobic organic compounds (HOCs) from contaminated soil/sediment in saline environments via in-situ enhanced sorption or ex-situ soil washing. Salinity effects on surfactant micelle formation and PHE partitioning into solution surfactant micelles and sorbed surfactant were investigated. The critical micelle concentration of surfactants decreased, and PHE partition between surfactant micelles and water increased with increasing salinity. Carbon-normalized partition coefficients (K ss ) of PHE onto the sorbed cationic surfactant increased significantly with increasing salinity, which illustrates a more pronounced immobilization of PHE by cationic surfactant in a saline system. Reduction of PHE sorption by anionic surfactant was more pronounced in the saline system, indicating that the anionic surfactant has a higher soil washing effectiveness in saline systems. - The effectiveness of surfactant-enhanced remediation technology was promoted when applying it in estuarine environment with a higher salinity.

  8. The Inhibiting or Accelerating Effect of Different Surfactants on ...

    African Journals Online (AJOL)

    NICO

    The course of differential capacity curves of the electric double layer at the mercury electrode/surfactant solution interface was described for three different surfactants from different groups. Using square-wave voltammetry (SWV) it was found that the surfactants had a varying effect on the kinetics of electroreduction of Zn2+ ...

  9. Micellization of a Cationic Surfactant in Mixed Aqueous and Non ...

    African Journals Online (AJOL)

    Reception

    surfactant molecules arrange themselves in bulk solutions into aggregates otherwise called micelles when the interface is fully saturated with the surfactant molecules. Micelle formation is driven by hydrophobic effect but opposed by electrostatic repulsion of the ionic head group (Jiang et al., 2009). Cationic surfactants like ...

  10. Effects of selected surfactants on soil microbial activity

    Science.gov (United States)

    Surfactants (surface-active agents) facilitate and accentuate the emulsifying, dispersing, spreading, and wetting properties of liquids. Surfactants are used in industry to reduce the surface tension of liquid and to solubilize compounds. For agricultural pest management, surfactants are an import...

  11. Cost Effective Surfactant Formulations for Improved Oil Recovery in Carbonate Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    William A. Goddard; Yongchun Tang; Patrick Shuler; Mario Blanco; Yongfu Wu

    2007-09-30

    This report summarizes work during the 30 month time period of this project. This was planned originally for 3-years duration, but due to its financial limitations, DOE halted funding after 2 years. The California Institute of Technology continued working on this project for an additional 6 months based on a no-cost extension granted by DOE. The objective of this project is to improve the performance of aqueous phase formulations that are designed to increase oil recovery from fractured, oil-wet carbonate reservoir rock. This process works by increasing the rate and extent of aqueous phase imbibition into the matrix blocks in the reservoir and thereby displacing crude oil normally not recovered in a conventional waterflood operation. The project had three major components: (1) developing methods for the rapid screening of surfactant formulations towards identifying candidates suitable for more detailed evaluation, (2) more fundamental studies to relate the chemical structure of acid components of an oil and surfactants in aqueous solution as relates to their tendency to wet a carbonate surface by oil or water, and (3) a more applied study where aqueous solutions of different commercial surfactants are examined for their ability to recover a West Texas crude oil from a limestone core via an imbibition process. The first item, regarding rapid screening methods for suitable surfactants has been summarized as a Topical Report. One promising surfactant screening protocol is based on the ability of a surfactant solution to remove aged crude oil that coats a clear calcite crystal (Iceland Spar). Good surfactant candidate solutions remove the most oil the quickest from the surface of these chips, plus change the apparent contact angle of the remaining oil droplets on the surface that thereby indicate increased water-wetting. The other fast surfactant screening method is based on the flotation behavior of powdered calcite in water. In this test protocol, first the calcite

  12. Development of cost-effective surfactant flooding technology. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pope, G.A.; Sepehrnoori, K.

    1996-11-01

    Task 1 of this research was the development of a high-resolution, fully implicit, finite-difference, multiphase, multicomponent, compositional simulator for chemical flooding. The major physical phenomena modeled in this simulator are dispersion, heterogeneous permeability and porosity, adsorption, interfacial tension, relative permeability and capillary desaturation, compositional phase viscosity, compositional phase density and gravity effects, capillary pressure, and aqueous-oleic-microemulsion phase behavior. Polymer and its non-Newtonian rheology properties include shear-thinning viscosity, permeability reduction, inaccessible pore volume, and adsorption. Options of constant or variable space grids and time steps, constant-pressure or constant-rate well conditions, horizontal and vertical wells, and multiple slug injections are also available in the simulator. The solution scheme used in this simulator is fully implicit. The pressure equation and the mass-conservation equations are solved simultaneously for the aqueous-phase pressure and the total concentrations of each component. A third-order-in-space, second-order-in-time finite-difference method and a new total-variation-diminishing (TVD) third-order flux limiter are used that greatly reduce numerical dispersion effects. Task 2 was the optimization of surfactant flooding. The code UTCHEM was used to simulate surfactant polymer flooding.

  13. Surfactant-Bound Monolithic Columns for Capillary Electrochromatography

    Science.gov (United States)

    Gu, Congying; He, Jun; Jia, Jinping; Fang, Nenghu; Shamsi, Shahab A.

    2010-01-01

    A novel anionic surfactant bound monolithic stationary phase based on 11-acrylaminoundecanoic acid (AAUA) is designed for capillary electrochromatography (CEC). The monolith possessing bonded undecanoyl groups (hydrophobic sites) and carboxyl groups (weak cationic ion-exchange sites) was evaluated as a mixed-mode stationary phase in CEC for the separation of neutral and polar solutes. Using a multivariate D-optimal design the composition of the polymerization mixture was modeled and optimized with five alkylbenzenes (ABs) and seven alkyl phenyl ketones (APKs) as test solutes. The D-optimal design indicates a strong dependence of electrochromatographic parameters on the concentration of AAUA monomer and porogen (water) in the polymerization mixture. A difference of 6%, 8% and 13% RSD between the predicted and the experimental values in terms of efficiency, resolution, and retention time, respectively, indeed confirmed that the proposed approach is practical. The physical (i.e., morphology, porosity and permeability) and chromatographic properties of the monolithic columns were thoroughly investigated. With the optimized monolithic column, high efficiency separation of N-methylcarbamates (NMCs) pesticides and positional isomers was successfully achieved. It appears that this type of mixed-mode monolith (containing both chargeable and hydrophobic sites) may have a great potential as a new generation of CEC stationary phase. PMID:19885887

  14. Consideration of Cosmetic Surgery As Part of Women's Benefit-Provisioning Mate Retention Strategy.

    Science.gov (United States)

    Atari, Mohammad; Barbaro, Nicole; Sela, Yael; Shackelford, Todd K; Chegeni, Razieh

    2017-01-01

    Individuals perform mate retention behaviors to minimize the risk of partner infidelity and relationship dissolution. The current study investigates whether consideration of cosmetic surgery can be conceptualized as part of a broader strategy of mate retention for women, but not men. We hypothesized that women's consideration of cosmetic surgery would be positively associated with performance frequencies of Benefit-Provisioning and Cost-Inflicting mate retention behaviors. We recruited 203 individuals (54% women) in committed heterosexual relationships from Tehran, Iran. Results indicate a positive association between consideration of cosmetic surgery and Benefit-Provisioning mate retention behaviors for women, but not men. There was no association between consideration of cosmetic surgery and Cost-Inflicting mate retention behaviors. Women therefore may consider cosmetic surgery to improve their physical attractiveness as part of a Benefit-Provisioning strategy to retain a long-term mate. We discuss limitations of the study and highlight future directions for research from an evolutionary perspective.

  15. Re-dissolution and de-compaction of DNA-cationic surfactant complexes using non-ionic surfactants.

    Science.gov (United States)

    Corbyn, Conrad P; Fletcher, Paul D I; Gemici, Rabia; Dias, Rita S; Miguel, Maria G

    2009-12-28

    Addition of a cationic surfactant to a solution of DNA causes the formation of compacted DNA-cationic surfactant complexes which precipitate from aqueous solution. It has been shown previously that addition of anionic surfactant will re-dissolve and de-compact the DNA-cationic surfactant complexes and we find that addition of non-ionic surfactants of the alkylpolyoxyethylene type can be used similarly. In principle, these de-compaction and re-dissolution processes could occur either by stripping of the cationic surfactant from the DNA into mixed micelles with the non-ionic surfactant or by solubilisation of the DNA-cationic surfactant complexes within the non-ionic micelles. Solubility phase-boundary measurements, fluorescence microscopy observations of the de-compaction process and light scattering results indicate that de-compaction and re-dissolution occur by the stripping mechanism, even for non-ionic surfactants where the favourable attractive electrostatic interaction between the two surfactants is absent. Using measurements of critical micelle concentrations and calculations based on regular solution mixed micelle theory, we show that re-dissolution and de-compaction of the DNA-cationic surfactant complexes occurs when the concentration of free monomeric cationic surfactant is reduced (by incorporation into mixed micelles) below a critical value.

  16. Particle retention during long discharges in Tore Supra and JET

    International Nuclear Information System (INIS)

    Loarer, T.; Tsitrone, E.; Brosset, C.; Bucalossi, J.; Gunn, J.; Joffrin, E.; Monier-Garbet, P.; Pegourie, B.; Thomas, P.; Lomas, P.; Ongena, J.

    2003-01-01

    The particle balances and the associated particle retentions for the long discharge experiments performed in Tore-Supra and for the L and H mode discharges carried out in JET are reported in this paper. From the reported experiments, the same particle retention behaviors are observed in Tore-Supra and JET in spite of the differences between the plasma geometry and the confinement mode (respectively limiter L-mode and divertor H-mode). A particle retention up to 70-80% of Γ(puff) for the larger gas injection has been obtained in JET. The particle retention behavior observed with the gas puff appears to be strongly dominant in the particle retention process. Indeed, no influence has been noticed from the active pumping, the saturation of the recycling area (0.4 D/C), the precedent discharges history (in terms of total 'particles retained' in the vessel) and even from the disruptions (conditioning). Also, the outgassing between discharges becomes negligible in terms of particle recovering when Γ(puff) and/or the discharge duration are increased. Finally, neither the edge localized modes (ELMs type-I or III) nor the disruptions modify the reported behaviour. For ITER, the particle retention is strictly limited and from the presented results it seems that strong gas injection should be avoided. (A.C.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Batigoec, Cigdem [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey); Akbas, Halide, E-mail: hakbas34@yahoo.com [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey); Boz, Mesut [Department of Chemistry, Faculty of Sciences, Trakya University, 22030 Edirne (Turkey)

    2011-12-15

    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 {Delta}G{sub cp}{sup 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-{alpha}-{omega}-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{sub 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 ({Delta}G{sub cp}{sup 0}), the enthalpy ({Delta}H{sub cp}{sup 0}) and the entropy ({Delta}S{sub cp}{sup 0}) of the clouding phenomenon were found positive in all cases. The standard free energy ({Delta}G{sub cp}{sup 0}) increased with increasing hydrophobic alkyl chain for both gemini and conventional cationic

  18. Pulmonary surfactant proteins and polymer combinations reduce surfactant inhibition by serum

    Science.gov (United States)

    Lu, Karen W.; Pérez-Gil, Jesús; Echaide, Mercedes; Taeusch, H. William

    2011-01-01

    Acute respiratory distress syndrome (ARDS) is an inflammatory condition that can be associated with capillary leak of serum into alveoli causing inactivation of surfactant. Resistance to inactivation is affected by types and concentrations of surfactant proteins, lipids, and polymers. Our aim was to investigate the effects of different combinations of these three components. A simple lipid mixture (DPPC/POPG) or a more complex lipid mixture (DPPC/POPC/POPG/cholesterol) was used. Native surfactant proteins SP-B and SP-C obtained from pig lung lavage were added either singly or combined at two concentrations. Also, non-ionic polymers polyethylene glycol and dextran and the anionic polymer hyaluronan were added either singly or in pairs with hyaluronan included. Non-ionic polymers work by different mechanisms than anionic polymers, thus the purpose of placing them together in the same surfactant mixture was to evaluate if the combination would show enhanced beneficial effects. The resulting surfactant mixtures were studied in the presence or absence of serum. A modified bubble surfactometer was used to evaluate surface activities. Mixtures that included both SP-B and SP-C plus hyaluronan and either dextran or polyethylene glycol were found to be the most resistant to inhibition by serum. These mixtures, as well as some with either SP-B or SP-C with combined polymers were as or more resistant to inactivation than native surfactant. These results suggest that improved formulations of lung surfactants are possible and may be useful in reducing some types of surfactant inactivation in treating lung injuries. PMID:21741354

  19. Structural study of surfactant-dependent interaction with protein

    Energy Technology Data Exchange (ETDEWEB)

    Mehan, Sumit; Aswal, Vinod K., E-mail: vkaswal@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kohlbrecher, Joachim [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen (Switzerland)

    2015-06-24

    Small-angle neutron scattering (SANS) has been used to study the complex structure of anionic BSA protein with three different (cationic DTAB, anionic SDS and non-ionic C12E10) surfactants. These systems form very different surfactant-dependent complexes. We show that the structure of protein-surfactant complex is initiated by the site-specific electrostatic interaction between the components, followed by the hydrophobic interaction at high surfactant concentrations. It is also found that hydrophobic interaction is preferred over the electrostatic interaction in deciding the resultant structure of protein-surfactant complexes.

  20. Physicochemical characteristics of PFC surfactants for dry decontamination

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Won Jin; Lee, Chi Woo [Korea University, Seoul (Korea)

    2001-04-01

    Even the trace amount of the used nuclear fuels of high radioactivity are hazardous to the earth and humans. Perfluorocarbons and perfluorocarbon surfactants are emerging to be efficient chemicals in the dry decontamination process of the used fuels of high radioactivity. The theme was undertaken to increase the knowledge on perfluorocarbon surfactants to develop the perfluorocarbon system in the dry decontamination process in Korea. Several cationic and anionic pfc surfactants were synthesized. Effects of pfc surfactants on electrochemical etching of silicon were investigated to form porous silicons. Forces were measured between silicon surfaces and AFM tip in the absence and presence of pfc surfactants. 7 refs., 10 figs. (Author)

  1. Thermally stable surfactants and compositions and methods of use thereof

    Science.gov (United States)

    Chaiko, David J [Woodridge, IL

    2008-09-02

    There are provided novel thermally stable surfactants for use with fillers in the preparation of polymer composites and nanocomposites. Typically, surfactants of the invention are urethanes, ureas or esters of thiocarbamic acid having a hydrocarbyl group of from 10 to 50 carbons and optionally including an ionizable or charged group (e.g., carboxyl group or quaternary amine). Thus, there are provided surfactants having Formula I: ##STR00001## wherein the variables are as defined herein. Further provided are methods of making thermally stable surfactants and compositions, including composites and nanocomposites, using fillers coated with the surfactants.

  2. Drug Retention Times

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2007-05-01

    The purpose of this monograph is to provide information on drug retention times in the human body. The information provided is based on plausible illegal drug use activities that might be engaged in by a recreational drug user. Based on anecdotal evidence, most people “party” during extended time away from the work environment. Therefore, the following scenarios were envisioned: (1) a person uses an illicit drug at a party on Saturday night (infrequent user); (2) a person uses a drug one time on Friday night and once again on Saturday night (infrequent user); and (3) a person uses a drug on Friday night, uses a drug twice on Saturday night, and once again on Sunday (frequent user).

  3. Study of polyacrylamide-surfactant system on the water–oil interface properties and rheological properties for EOR

    Directory of Open Access Journals (Sweden)

    S.Z. Mahdavi

    2017-12-01

    Full Text Available Nowadays, due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR techniques have been considered by a large number of scientists and company. Situ oil extraction is normally done by these techniques with high efficiency. In this particular study, five different surface active agents (surfactant, two kinds of oil with various API, two kinds of sulfonated polyacrylamide, two different electrolyte solutions with various TDS and two distinctive alcohols were tested and evaluated. An optimal formulation in terms of the properties and quantity of materials has to be used in order to enhance oil recovery, achieved by investigation of surface tension and the phase behavior of mentioned substances. Rheological behavior of polymer flooding and surfactant was studied. Employing this formulation, the maximum micro emulsion of oil in water occurred. Due to the synergy between surfactant and alcohol (as a co-surfactant, relatively lower amounts of surfactants were used which led to the dip in the cost of operation, and ultimately the efficiency of operation improved.

  4. Surfactant enhanced non-classical extraction

    International Nuclear Information System (INIS)

    Szymanowski, J.

    1999-01-01

    Surfactant enhanced non-classical extractions are presented and discussed. They include micellar enhanced ultrafiltration and cloud point extraction. The ideas of the processes are given and the main features are presented. They are compared to the classical solvent extraction. The fundamental of micellar solutions and their solubilization abilities are also discussed. (author)

  5. 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...

  6. Surfactant protein D is proatherogenic in mice

    DEFF Research Database (Denmark)

    Sorensen, Grith L; Madsen, Jens; Kejling, Karin

    2006-01-01

    Surfactant protein D (SP-D) is an important innate immune defense molecule that mediates clearance of pathogens and modulates the inflammatory response. Moreover, SP-D is involved in lipid homeostasis, and pulmonary accumulation of phospholipids has previously been observed in SP-D-deficient (Spd...

  7. Lung Surfactant - The Indispensable Component of Respiratory ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 8. Lung Surfactant - The Indispensable Component of Respiratory Mechanics. Shweta Saxena. Research News Volume 10 Issue 8 August 2005 pp 91-96. Fulltext. Click here to view fulltext PDF. Permanent link:

  8. Topological transformation of a surfactant bilayer

    DEFF Research Database (Denmark)

    Le, T.D.; Olsson, U.; Mortensen, K.

    2000-01-01

    Surfactant lamellar phases are often complicated by the formation of multilamellar (onions) under shear, which can originate simply by shaking the sample. A systematic study has been performed on the C10E3-D2O system in which different bilayer structures under a steady shear flow were investigated...

  9. EFFECT OF SURFACTANTS ON THE MECHANICAL PROPERTIES ...

    African Journals Online (AJOL)

    The purpose of this study was to investigate the effect of non ionic surfactant on the mechanical properties of acetaminophen-wax matrix tablet and hence its implication on dissolution profile. Acetaminophen-wax matrix granules were prepared by melt granulation technique. This was formed by triturating acetaminophen ...

  10. Molecular dynamics of surfactant protein C

    DEFF Research Database (Denmark)

    Ramírez, Eunice; Santana, Alberto; Cruz, Anthony

    2006-01-01

    Surfactant protein C (SP-C) is a membrane-associated protein essential for normal respiration. It has been found that the alpha-helix form of SP-C can undergo, under certain conditions, a transformation from an alpha-helix to a beta-strand conformation that closely resembles amyloid fibrils, which...

  11. Influence of surfactant concentration on nanohydroxyapatite growth

    Indian Academy of Sciences (India)

    Nanohydroxyapatite particles with different morphologies were synthesized through a microwave coupled hydrothermal method using CTAB as a template. A successful synthesis of nanosized HAP spheres, rods and fibres is achieved through this method by controlling the concentration of the surfactant. The concentration ...

  12. Surfactant free metal chalcogenides microparticles consisting of ...

    Indian Academy of Sciences (India)

    SANYASINAIDU GOTTAPU

    2017-11-11

    Nov 11, 2017 ... Abstract. A versatile methodology for the production of organic surfactant-free metal chalcogenide microparticles consisting of nano crystallites at room temperature in a short time is described. The reaction of various metal sources with LiBH4 in the presence of either S or Se yielded their corresponding ...

  13. Influence of surfactant concentration on nanohydroxyapatite growth

    Indian Academy of Sciences (India)

    Abstract. Nanohydroxyapatite particles with different morphologies were synthesized through a microwave cou- pled hydrothermal method using CTAB as a template. A successful synthesis of nanosized HAP spheres, rods and fibres is achieved through this method by controlling the concentration of the surfactant.

  14. Influence of surfactant concentration on nanohydroxyapatite growth

    Indian Academy of Sciences (India)

    4Corrosion Science and Technology Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 012, India. MS received 17 ... fibres is achieved through this method by controlling the concentration of the surfactant. The concentration of the ... shown that many clinical applications of HAp mainly depend on shape ...

  15. Intratracheal atomized surfactant provides similar outcomes as bolus surfactant in preterm lambs with respiratory distress syndrome.

    Science.gov (United States)

    Milesi, Ilaria; Tingay, David G; Zannin, Emanuela; Bianco, Federico; Tagliabue, Paolo; Mosca, Fabio; Lavizzari, Anna; Ventura, Maria Luisa; Zonneveld, C Elroy; Perkins, Elizabeth J; Black, Don; Sourial, Magdy; Dellacá, Raffaele L

    2016-07-01

    Aerosolization of exogenous surfactant remains a challenge. This study is aimed to evaluate the efficacy of atomized poractant alfa (Curosurf) administered with a novel atomizer in preterm lambs with respiratory distress syndrome. Twenty anaesthetized lambs, 127 ± 1 d gestational age, (mean ± SD) were instrumented before birth and randomized to receive either (i) positive pressure ventilation without surfactant (Control group), (ii) 200 mg/kg of bolus instilled surfactant (Bolus group) at 10 min of life or (iii) 200 mg/kg of atomized surfactant (Atomizer group) over 60 min from 10 min of life. All lambs were ventilated for 180 min with a standardized protocol. Lung mechanics, regional lung compliance (electrical impedance tomography), and carotid blood flow (CBF) were measured with arterial blood gas analysis. Dynamic compliance and oxygenation responses were similar in the Bolus and Atomizer groups, and both better than Control by 180 min (all P < 0.05; two-way ANOVA). Both surfactant groups demonstrated more homogeneous regional lung compliance throughout the study period. There were no differences in CBFConclusion:In a preterm lamb model, atomized surfactant resulted in similar gas exchange and mechanics as bolus administration. This study suggests evaluation of supraglottic atomization with this system when noninvasive support is warranted.

  16. Research Synopsis: Spring 1983 Retention.

    Science.gov (United States)

    Peralta Community Coll. District, Oakland, CA. Office of Research, Planning and Development.

    An analysis of spring 1983 retention rates and grade distributions within the Peralta Community College District (PCCD) revealed: (1) College of Alameda had the highest successful retention rate in the PCCD, defined as the total of all students who completed the term with a grade of A, B, C, D, or CR (credit); (2) the PCCD's successful retention…

  17. Lung surfactants and different contributions to thin film stability.

    Science.gov (United States)

    Hermans, Eline; Bhamla, M Saad; Kao, Peter; Fuller, Gerald G; Vermant, Jan

    2015-11-07

    The surfactant lining the walls of the alveoli in the lungs increases pulmonary compliance and prevents collapse of the lung at the end of expiration. In premature born infants, surfactant deficiency causes problems, and lung surfactant replacements are instilled to facilitate breathing. These pulmonary surfactants, which form complex structured fluid-fluid interfaces, need to spread with great efficiency and once in the alveolus they have to form a thin stable film. In the present work, we investigate the mechanisms affecting the stability of surfactant-laden thin films during spreading, using drainage flows from a hemispherical dome. Three commercial lung surfactant replacements Survanta, Curosurf and Infasurf, along with the phospholipid dipalmitoylphosphatidylcholine (DPPC), are used. The surface of the dome can be covered with human alveolar epithelial cells and experiments are conducted at the physiological temperature. Drainage is slowed down due to the presence of all the different lung surfactant replacements and therefore the thin films show enhanced stability. However, a scaling analysis combined with visualization experiments demonstrates that different mechanisms are involved. For Curosurf and Infasurf, Marangoni stresses are essential to impart stability and interfacial shear rheology does not play a role, in agreement with what is observed for simple surfactants. Survanta, which was historically the first natural surfactant used, is rheologically active. For DPPC the dilatational properties play a role. Understanding these different modes of stabilization for natural surfactants can benefit the design of effective synthetic surfactant replacements for treating infant and adult respiratory disorders.

  18. Influence of stability of polymer surfactant on oil displacement mechanism

    Science.gov (United States)

    Liu, Li; Li, Chengliang; Pi, Yanming; Wu, Di; He, Ying; Geng, Liang

    2018-02-01

    At present, most of the oilfields of China have entered the late stage of high water-cut development, and three oil recovery technique has become the leading technology for improving oil recovery. With the improvement of three oil recovery techniques, the polymer surfactant flooding technology has been widely promoted in oil fields in recent years. But in the actual field experiment, it has been found that the polymer surfactant has chromatographic separation at the extraction end, which indicates that the property of the polymer surfactant has changed during the displacement process. At present, there was few literature about how the stability of polymer surfactant affects the oil displacement mechanism. This paper used HuaDing-I polymer surfactant to conduct a micro photolithography glass flooding experiment, and then compared the oil displacement law of polymer surfactant before and after static setting. Finally, the influence law of stability of polymer surfactant on the oil displacement mechanism is obtained by comprehensive analysis.

  19. Military Retention. A Comparative Outlook

    Directory of Open Access Journals (Sweden)

    Vasile Sminchise

    2016-06-01

    Full Text Available One of the main goals for human resources management structures and for armed forces leaders is to maintain all necessary personnel, both qualitatively and quantitatively for operational needs or for full required capabilities. The retention of military personnel is essential to keep morale and unit readiness and to reduce the costs for recruiting, training, replacement of manpower. Retention rates depend not only on money or other social measures. The goal for retention is to keep in use the most valuable resource that belongs to an organization: the human beings and their knowledge. The aim pf this paper is to provide a comparative analysis of retention measures in various countries based on Research and Technology Organisation report released in 2007 and, thus, provide more examples of retention measures as far as the Romanian military system is concerned.

  20. Optimizing the surfactant for the aqueous processing of LiFePO{sub 4} composite electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Porcher, W.; Jouanneau, S. [Commissariat a l' Energie Atomique, 38054 Grenoble Cedex 9 (France); Lestriez, B.; Guyomard, D. [Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes, CNRS, 44322 Nantes Cedex 3 (France)

    2010-05-01

    Aqueous processing would reduce the costs associated with the making of the composite electrode. To achieve the incorporation and the dispersion of the carbon black (CB) conductive agent in aqueous slurries, a surfactant is needed. In this paper, three surfactants are compared, an anionic one, the sodium dodecyle sulphate (SDS), a non-ionic one, the isooctylphenylether of polyoxyethylene called commercially Triton X-100 and a cationic one, the hexadecyltrimethylammonium bromide (CTAB), by using rheology and laser granulometry measurements on electrode slurries on one hand, and SEM observations, porosity and adhesion measurements and electrochemical testing on composite electrodes on the other hand. Ionic surfactants were found to be not suitable because a corrosion of the aluminium current collector occurred. The utilization of Triton X-100 favoured a more homogeneous CB distribution, resulted in a better electronic wiring of the active material particles and higher rate behavior of the electrode. Optimal electrochemical performances are obtained for an optimal surfactant concentration which depends on the BET surface area of the CB powder. (author)

  1. Hydrate crystallization at oil-water interface, the effect of nonionic surfactants

    Science.gov (United States)

    Rosenfeld, Liat; Dann, Kevin; Rosenfeld Team

    2017-11-01

    Gas hydrates pose economic and environmental risks to the oil and gas industry when plug formation occurs in pipelines. A novel approach using interfacial rheology and visualization techniques was applied to understand cyclopentane clathrate hydrate formation in the presence of nonionic surfactant to achieve hydrate inhibition at low percent weight compared to thermodynamic inhibitors. The hydrate-inhibiting performance of various surfactants on a manually nucleated 2 μL droplet showed a morphological shift in crystallization from planar shell growth to conical growth. Monitoring the internal pressure of the water droplet undergoing hydrate crystallization provides information on the change of interfacial tension during crystallization process. At low surfactant concentrations, planar hydrate crystal was formed and decreasing interfacial tension was observed. At high surfactant concentration, crystal morphology was shifted to conical. Interfacial tension measurements reveal oscillations of interfacial tension during the crystallization process. The oscillatory behavior of the interfacial tension is a result of the growth and release of the hydrate cones from the surface of the droplet.

  2. The effect of surfactants on path instability of a rising bubble

    Science.gov (United States)

    Tagawa, Yoshiyuki; Takagi, Shu; Matsumoto, Yoichiro

    2013-11-01

    We experimentally investigate the surfactant effect on path instability of an air bubble rising in quiescent water. An addition of surfactant varies the gas-water boundary condition from zero shear stress to non-zero shear stress. We report three main findings: firstly, while the drag force acting on the bubble increases with the surfactant concentration as expected, the lift force shows a non-monotonic behavior; secondly, the transient trajectory starting from helical to zigzag is observed, which has never been reported in the case of purified water; lastly, a bubble with the intermediate slip conditions between free-slip and no-slip show a helical motion for a broad range of the Reynolds number. Aforementioned results are rationalized by considering the adsorption-desorption kinetics of the surfactants on gas-water interface and the wake dynamics. Y.T. thanks for financial support from Grant-in-Aid for JSPS Fellows (20-10701). We also thank for Grant-in-Aid for Scientific Research (B) (21360079).

  3. Synergistic effect of non-ionic surfactants Tween 80 and PEG6000 on cytotoxicity of insecticides.

    Science.gov (United States)

    Li, Diqiu; Wu, Xiwei; Yu, Xiaoqin; Huang, Qingchun; Tao, Liming

    2015-03-01

    The use of surfactants in the development of a suitable formulation for insecticides should improve the solubility behavior, the permeability and the efficiency against pests meanwhile decrease the toxic risks of insecticides on human health. Cytotoxicity of insecticides including abamectin, chlorfluazuron, hexaflumuron, chlorpyrifos, and tebufenozide was assessed on human HepG2 and lepidopteran Tn5B1-4 cells utilizing insecticide alone and in combination with nontoxic concentrations of nonionic surfactants Tween 80 and PEG6000. The results showed avermection revealed high cytotoxicity, chlorfluazuron and hexaflumuron possessed median cytotoxicity, and chlorpyrifos and tebufenozide had little cytotoxicity on HepG2 and Tn5B1-4 cells. The co-incubation with Tween 80 and PEG6000 powerfully counteracted the cytotoxicity of avermectin. Tween 80 enhanced, whereas PEG6000 compressed, the cytotoxicity of chlorfluazuron on Tn5B1-4 cells, and also improved a bit of the cytotoxicity of chlorpyrifos or tebufenozide on HepG2 cells. PEG6000 was more suitable to be used as surfactant in improving insecticide solubility and reducing the cytotoxicity. The present investigation demonstrates the necessity of utilizing surfactants to weaken the cytotoxicity of insecticides. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Influence of Surfactants on Sodium Chloride Crystallization in Confinement.

    Science.gov (United States)

    Qazi, Mohsin J; Liefferink, Rinse W; Schlegel, Simon J; Backus, Ellen H G; Bonn, Daniel; Shahidzadeh, Noushine

    2017-05-02

    We study the influence of different surfactants on NaCl crystallization during evaporation of aqueous salt solutions. We found that at concentrations of sodium chloride close to saturation, only the cationic surfactant CTAB and the nonionic surfactant Tween 80 remain stable. For the nonionic surfactant, the high concentration of salt does not significantly change either the critical micellar concentration (CMC) or the surface tension at the CMC; for the cationic surfactant, the CMC is reduced by roughly 2 orders of magnitude upon adding the salt. The presence of both types of surfactants in the salt solution delays the crystallization of sodium chloride with evaporation. This, in turn, leads to high supersaturation which induces the rapid precipitation of a hopper crystal in the bulk. The crystallization inhibitor role of these surfactants is shown to be mainly due to the passivation of nucleation sites at both liquid/air and solid/liquid interfaces rather than a change in the evaporation rate which is found not to be affected by the presence of the surfactants. The adsorption of surfactants at the liquid/air interface prevents the crystallization at this location which is generally the place where the precipitation of sodium chloride is observed. Moreover, sum frequency generation spectroscopy measurements show that the surfactants are also present at the solid/liquid interface. The incorporation of the surfactants into the salt crystals is investigated using a novel, but simple, method based on surface tension measurements. Our results show that the nonionic surfactant Tween 80 is incorporated in the NaCl crystals but the cationic surfactant CTAB is not. Taken together, these results therefore allow us to establish the effect of the presence of surfactants on sodium chloride crystallization.

  5. Husband's Esteem Predicts his Mate Retention Tactics

    Directory of Open Access Journals (Sweden)

    Christopher J. Holden

    2014-07-01

    Full Text Available delity or prevent their defection from the relationship. These tactics include low-risk acts that render the current relationship more attractive by bestowing benefits on the woman, as well as cost-inflicting acts that render defection from the relationship risky or dangerous for her. Previous research has linked men's mate retention behavior with men's mate value (value as a current or potential partner using women's reports. The current research addresses limitations of that research using self-reports and cross-spousal reports from 107 married couples concerning their self-esteem and their esteem for their partner. The results indicate that the level of esteem that wives have for their husbands is positively associated with their perception of their husband's use of positive inducements and negatively associated with their husband's self-reported use of cost-inflicting mate retention behaviors (i.e., Direct Guarding, Intersexual Negative Inducements, and Intrasexual Negative Inducements. The level of self-esteem reported by men was negatively associated with their self-reported direct guarding behavior. Discussion explores the possibility that esteem—both self-esteem and esteem from one's partner—functions as an internal gauge of relative mate value.

  6. Effect of the cationic surfactant moiety on the structure of water entrapped in two catanionic reverse micelles created from ionic liquid-like surfactants.

    Science.gov (United States)

    Villa, Cristian C; Silber, Juana J; Correa, N Mariano; Falcone, R Darío

    2014-10-06

    The behavior of water entrapped in reverse micelles (RMs) formed by two catanionic ionic liquid-like surfactants, benzyl-n-hexadecyldimethylammonium 1,4-bis-2-ethylhexylsulfosuccinate (AOT-BHD) and cetyltrimethylammonium 1,4-bis-2-ethylhexylsulfosuccinate (AOT-CTA), was investigated by using dynamic (DLS) and static (SLS) light scattering, FTIR, and (1)H NMR spectroscopy techniques. To the best of our knowledge, this is the first report in which AOT-CTA has been used to create RMs and encapsulate water. DLS and SLS results revealed the formation of RMs in benzene and the interaction of water with the RM interface. From FTIR and (1)H NMR spectroscopy data, a difference in the magnitude of the water-catanionic surfactant interaction at the interface is observed. For the AOT-BHD RMs, a strong water-surfactant interaction can be invoked whereas for AOT-CTA this interaction seems to be weaker. Consequently, more water molecules interact with the interface in AOT-BHD RMs with a completely disrupted hydrogen-bond network, than in AOT-CTA RMs in which the water structure is partially preserved. We suggest that the benzyl group present in the BHD(+) moiety in AOT-BHD is responsible for the behavior of the catanionic interface in comparison with the interface created in AOT-CTA. These results show that a simple change in the cationic component in the catanionic surfactant promotes remarkable changes in the RMs interface with interesting consequences, in particular when using the systems as nanoreactors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. The impact of nonionic surfactant additives on the nonequilibrium association between oppositely charged polyelectrolytes and ionic surfactants.

    Science.gov (United States)

    Fegyver, Edit; Mészáros, Róbert

    2014-03-28

    The effect of uncharged surfactant additives on the oppositely charged polyion/ionic surfactant complexation is usually described as a direct equilibrium association between the polyelectrolyte molecules and free mixed micelles analogous to the polyion/colloidal particle interactions. This approach predicts that the binding of the ionic surfactant to the polyelectrolyte molecules can be completely suppressed by increasing the nonionic-to-ionic surfactant ratio. In the present work, it is shown that the addition of nonionic surfactants to poly(diallyldimethylammonium chloride)/sodium dodecyl sulfate mixtures considerably enhances the binding of the anionic surfactant to the polycation in the dilute surfactant concentration regime. The dynamic light scattering, turbidity, electrophoretic mobility and fluorescence spectroscopic measurements are consistent with the synergic binding of the ionic and nonionic surfactants to the polyelectrolyte molecules. The enhanced surfactant binding could be utilized for the preparation of stable colloidal dispersions of novel polyion/mixed surfactant nanoparticles over a wide composition range provided that adequate mixing protocols are used. These results clearly indicate that the nonionic surfactant additives can be successfully used to tune the nonequilibrium association of oppositely charged macromolecules and amphiphiles.

  8. Effect of counterions on properties of micelles formed by alkylpyridinium surfactants .1. Conductometry and H-1-NMR chemical shifts

    NARCIS (Netherlands)

    Bijma, K; Engberts, J.B.F.N.

    1997-01-01

    This paper delineates the influence of counterions on the aggregation behavior of 1-methyl-4-n-dodecylpyridinium surfactants, using conductometry and H-1-NMR spectroscopy. Three types of counterions have been studied: (i) halides, (ii) alkanesulfonates, and (iii) aromatic counterions. The critical.

  9. Structure and Conformational Dynamics of DMPC/Dicationic Surfactant and DMPC/Dicationic Surfactant/DNA Systems

    Science.gov (United States)

    Pietralik, Zuzanna; Krzysztoń, Rafał; Kida, Wojciech; Andrzejewska, Weronika; Kozak, Maciej

    2013-01-01

    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. PMID:23571492

  10. Interactions in mixed micellar systems of an amphoteric chelating surfactant and ionic surfactants.

    Science.gov (United States)

    Svanedal, Ida; Persson, Gerd; Norgren, Magnus; Edlund, Håkan

    2014-02-11

    Mixtures of ionic surfactants and the chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of interactions in mixed micellar systems. The amphoteric 4-C12-DTPA is zwitterionic with a negative net charge at the studied pH levels. The investigated ionic surfactants were the cationic dodecyltrimethylammonium chloride (DoTAC), the anionic sodium dodecyl sulfate (SDS), and the zwitterionic dimethyldodecylamine-N-oxide (DDAO). The surfactants all have the same hydrophobic chain lengths, and the results are evaluated in terms of headgroup interactions. 4-C12-DTPA interacts with different ionic surfactants by accepting or donating protons to the aqueous solution to increase the attractive interactions between the two surfactants; i.e., the protonation equilibrium of 4-C12-DTPA is shifted in different directions depending on whether there are predominant repulsions between positively or negatively charged groups in the mixed micelles. This was monitored by measuring pH vs concentration in the mixed systems. By measuring the pH, it was also possible to study the shift in the protonation equilibrium at increasing concentration, as the composition in the micelles approaches the composition in the total solution. Following the approach of Rubingh's regular solution theory, the interaction parameter β for mixed micelle formation was calculated from the cmc values determined by NMR diffusometry. Synergism in mixed micelle formation and negative β parameters were found in all of the investigated systems. As expected, the most negative β parameter was found in the mixture with DoTAC, followed by DDAO and SDS. The self-diffusion in the 4-C12-DTPA/DoTAC system was also discussed. The self-diffusion coefficient vs concentration plots show two distinctly different curves, depending on the surfactant that is present in excess.

  11. Job embeddedness and nurse retention.

    Science.gov (United States)

    Reitz, O Ed; Anderson, Mary Ann; Hill, Pamela D

    2010-01-01

    Nurse retention is a different way of conceptualizing the employer-employee relationship when compared with turnover. Job embeddedness (JE), a construct based on retention, represents the sum of reasons why employees remain at their jobs. However, JE has not been investigated in relation to locale (urban or rural) or exclusively with a sample of registered nurses (RNs). The purpose of this study was to determine what factors (JE, age, gender, locale, and income) help predict nurse retention. A cross-sectional mailed survey design was used with RNs in different locales (urban or rural). Job embeddedness was measured by the score on the composite, standardized instrument. Nurse retention was measured by self-report items concerning intent to stay. A response rate of 49.3% was obtained. The typical respondent was female (96.1%), white, non-Hispanic (87.4%), and married (74.9%). Age and JE were predictive of nurse retention and accounted for 26% of the explained variance in intent to stay. Although age was a significant predictor of intent to stay, it accounted for only 1.4% of the variance while JE accounted for 24.6% of the variance of nurse retention (as measured by intent to stay). Older, more "embedded" nurses are more likely to remain employed in their current organization. Based on these findings, JE may form the basis for the development of an effective nurse retention program.

  12. Surfactant Based Enhanced Oil Recovery and Foam Mobility Control

    Energy Technology Data Exchange (ETDEWEB)

    George J. Hirasaki; Clarence A. Miller

    2006-09-09

    Surfactant flooding has the potential to significantly increase recovery over that of conventional waterflooding. The availability of a large number of surfactant structures makes it possible to conduct a systematic study of the relation between surfactant structure and its efficacy for oil recovery. A mixture of two surfactants was found to be particularly effective for application in carbonate formations at low temperature. The mixture is single phase for higher salinity or calcium concentrations than that for either surfactant used alone. This makes it possible to inject the surfactant slug with polymer close to optimal conditions and yet be single phase. A formulation has been designed for a particular field application. It uses partially hydrolyzed polyacrylamide for mobility control. The addition of an alkali such as sodium carbonate makes possible in situ generation of naphthenic soap and significant reduction of synthetic surfactant adsorption. The design of the process to maximize the region of ultra-low IFT takes advantage of the observation that the ratio of soap to synthetic surfactant is a parameter in the conditions for optimal salinity. Even for a fixed ratio of soap to surfactant, the range of salinity for low IFT was wider than that reported for surfactant systems in the literature. Low temperature, forced displacement experiments in dolomite and silica sandpacks demonstrate that greater than 95% recovery of the waterflood remaining oil is possible with 0.2% surfactant concentration, 0.5 PV surfactant slug, with no alcohol. Compositional simulation of the displacement process demonstrates the role of soap/surfactant ratio on passage of the profile through the ultralow IFT region, the importance of a wide salinity range of low IFT, and the importance of the viscosity of the surfactant slug. Mobility control is essential for surfactant EOR. Foam is evaluated to improve the sweep efficiency of surfactant injected into fractured reservoirs as well as a

  13. Payload retention device

    Science.gov (United States)

    Monford, Leo G., Jr.

    1992-06-01

    A payload retention device for grappling and retaining a payload in docked position on a supporting structure in the cargo bay of a space vehicle is presented. The device comprises a two-fault tolerant electromagnetic grappling system comprising electromagnets for attracting and grappling a grapple strike plate affixed to the payload when in proximity thereto and an electromechanical latching assembly comprising a pair of independent latching subassemblies. Each subassembly comprises a set of latching pawls which are driven into latching and unlatching positions relative to a grappled payload by a pair of gearmotors, each equipped with a ratchet clutch drive mechanism which is two-fault tolerant with respect to latching such that only one gearmotor of the four needs to be operational to effect a latch of the payload but is single fault tolerant with respect to release of a latched payload. Sensors are included for automatically sensing the magnetic grappling of a payload and for automatically de-energizing the gearmotors of the latching subassemblies when a latch condition is achieved.

  14. Small-angle neutron-scattering studies of mixed micellar structures made of dimeric surfactants having imidazolium and ammonium headgroups.

    Science.gov (United States)

    Pal, Asish; Datta, Sougata; Aswal, V K; Bhattacharya, Santanu

    2012-11-08

    Planar imidazolium cation based gemini surfactants [16-Im-n-Im-16], 2Br(-) (where n = 2, 3, 4, 5, 6, 8, 10, and 12), exhibit different morphologies and internal packing arrangements by adopting different supramolecular assemblies in aqueous media depending on their number of spacer methylene units (CH(2))(n). Detailed measurements of the small-angle neutron-scattering (SANS) cross sections from different imidazolium-based surfactant micelles in aqueous media (D(2)O) are reported. The SANS data, containing the information of aggregation behavior of such surfactants in the molecular level, have been analyzed on the basis of the Hayter and Penfold model for the macro ion solution to compute the interparticle structure factor S(Q) taking into account the screened Coulomb interactions between the dimeric surfactant micelles. The characteristic changes in the SANS spectra of the dimeric surfactant with n = 4 due to variation of temperature have also been investigated. These data are then compared with the SANS characterization data of the corresponding gemini micelles containing tetrahedral ammonium ion based polar headgroups. The critical micellar concentration of each surfactant micelle (cmc) has been determined using pyrene as an extrinsic fluorescence probe. The variation of cmc as a function of spacer chain length has been explained in terms of conformational variation and progressive looping of the spacer into the micellar interior upon increasing the n values. Small-angle neutron-scattering (SANS) cross sections from different mixed micelles composed of surfactants with ammonium headgroups, 16-A(0), [16-Am-n-Am-16], 2Br(-) (where n = 4), 16-I(0), and [16-Im-n-Im-16], 2Br(-) (where n = 4), in aqueous media (D(2)O) have also been analyzed. The aggregate composition matches with that predicted from the ideal mixing model.

  15. Cycle-Induced Flow and Surfactant Transport in an Alveolus

    Science.gov (United States)

    Wei, H. H.

    2002-11-01

    The flow and transport in an alveolus are of fundamental importance to partial liquid ventilation, surfactant transport, pulmonary drug administration, cell-cell signaling pathways and gene therapy. We model the system in which an alveolus is partially filled with liquid in the presence of surfactants. Assuming a circular interface due to sufficiently strong surface tension, we can apply two-dimensional bipolar coordinates to describe the system. We then combine analytical and numerical techniques to solve the Stokes flow and the surfactant concentration. In the absence of surfactants, there is no steady streaming because of reversibility of the Stokes flow. The presence of surfactants however induces a non-trivial cycle-averaged surfactant concentration gradient along the interface that generates steady streaming. The steady streaming patterns (e.g., number of vortices) depend on the parameters, especially on the ratio of inspiration to expiration periods (I:E ratio). Either smaller or larger I:E ratio exhibits two primary vortices but the direction of primary vortices for small I:E is opposite to large I:E. Extension to soluble surfactants is also discussed. For sufficiently high surfactant bulk concentration, the surfactant transport is sorption-controlled and soluble surfactants diminish the size of steady vortices near the alveolar opening. For the estimated steady velocity u 10-5 cm/s, the corresponding Peclet number is 10-7/ D_m. Therefore, for Dm <= 10-7 cm^2/s, the convective transport dominates.

  16. Tuning of nanoparticle-surfactant interactions in aqueous system

    Science.gov (United States)

    Kumar, Sugam; Aswal, V. K.

    2011-01-01

    The interaction of charged (anionic) silica nanoparticles with ionic and nonionic surfactants has been studied using small-angle neutron scattering (SANS). The surfactants used are anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB) and nonionic decaoxyethylene n-dodecylether (C12E10). The measurements are carried out at fixed concentration (1 wt%) of silica nanoparticles and with surfactant concentration varied in the range 0-2 wt%. It is found that there is no direct interaction between the nanoparticles and the surfactant (SDS) when they both are similarly charged. Both the silica nanoparticles and micelles coexist individually with no significant change in the structure of the micelles with respect to that in the pure surfactant solution. On the other hand, the presence of oppositely charged surfactant (DTAB) leads to the aggregation of silica nanoparticles even with very low surfactant concentration. The aggregation of silica nanoparticles is characterized by fractal structure and its fractal dimension remains constant with the increase in the surfactant concentration. In the case of nonionic surfactant, it interacts with the individual silica nanoparticles. The interaction is examined using two models: one that considers the surfactant layer coating on silica nanoparticles and a second one where the surface of the nanoparticles is decorated by the micelles. Contrast variation SANS measurements confirm the uniform decoration of nonionic micelles on the nanoparticles.

  17. Tuning of nanoparticle-surfactant interactions in aqueous system

    International Nuclear Information System (INIS)

    Kumar, Sugam; Aswal, V K

    2011-01-01

    The interaction of charged (anionic) silica nanoparticles with ionic and nonionic surfactants has been studied using small-angle neutron scattering (SANS). The surfactants used are anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB) and nonionic decaoxyethylene n-dodecylether (C 12 E 10 ). The measurements are carried out at fixed concentration (1 wt%) of silica nanoparticles and with surfactant concentration varied in the range 0-2 wt%. It is found that there is no direct interaction between the nanoparticles and the surfactant (SDS) when they both are similarly charged. Both the silica nanoparticles and micelles coexist individually with no significant change in the structure of the micelles with respect to that in the pure surfactant solution. On the other hand, the presence of oppositely charged surfactant (DTAB) leads to the aggregation of silica nanoparticles even with very low surfactant concentration. The aggregation of silica nanoparticles is characterized by fractal structure and its fractal dimension remains constant with the increase in the surfactant concentration. In the case of nonionic surfactant, it interacts with the individual silica nanoparticles. The interaction is examined using two models: one that considers the surfactant layer coating on silica nanoparticles and a second one where the surface of the nanoparticles is decorated by the micelles. Contrast variation SANS measurements confirm the uniform decoration of nonionic micelles on the nanoparticles.

  18. How to overcome surfactant dysfunction in meconium aspiration syndrome?

    Science.gov (United States)

    Mokra, Daniela; Calkovska, Andrea

    2013-06-01

    Surfactant dysfunction in meconium aspiration syndrome (MAS) is caused by meconium components, by plasma proteins leaking through the injured alveolocapillary membrane and by substances originated in meconium-induced inflammation. Surfactant inactivation in MAS may be diminished by several ways. Firstly, aspirated meconium should be removed from the lungs to decrease concentrations of meconium inhibitors coming into the contact with surfactant in the alveolar compartment. Once the endogenous surfactant becomes inactivated, components of surfactant should be substituted by exogenous surfactant at a sufficient dose, and surfactant administration should be repeated, if oxygenation remains compromised. To delay the inactivation by inhibitors, exogenous surfactants may be enriched with surfactant proteins, phospholipids, or other substances such as polymers. Finally, to diminish an adverse action of products of meconium-induced inflammation on both endogenous and exogenously delivered surfactant, anti-inflammatory drugs may be administered. A combined therapeutic approach may result in better outcome in patients with MAS and in lower costs of treatment. Copyright © 2013. Published by Elsevier B.V.

  19. [ANTIMICROBIAL ACTION OF NOCARDIA VACCINII IMV B-7405 SURFACTANTS].

    Science.gov (United States)

    Pirog, T P; Beregova, K A; Savenko, I V; Shevchuk, T A; Iutynska, G O

    2015-01-01

    To study the effect of Nocardia vaccinii IMV B-7405 surfactants on some bacteria (including pathogens of genera Proteus, Staphylococcus, Enterobacter), yeast of Candida species and fungi (Aspergillus niger R-3, Fusarium culmorum T-7). The antimi- crobial properties of surfactant were determined in suspension culture by Koch method and also by index of the minimum inhibitory concentration. Surfactants were extracted from supernatant of cultural liquid by mixture of chloroform and methanol (2:1). It is shown that the antimicrobial properties of N. vaccinii IMV B-7405 surfactant depended on the degree of purification (supernatant, solution of surfactant), concentration and exposure. Survival of Escherichia coli IEM-1 and Bacillus subtilis BT-2 (both vegetative cells and spores) after treatment for 1-2 hours with surfactants solution and the supernatant (the surfactant concentration 21 µg/ml) was 3-28%. Minimum inhibitory concentrations of N. vaccinii IMV B-7405 surfactants on studied bacteria, yeast and micromycetes were 11.5-85.0; 11.5-22.5 and 165.0-325.0 µ/ml respectively. Minimum inhibitory concentrations of N. vaccinii IMV B-7405 surfactants are comparable to those of the known microbial surfactants. The possibility of using the supernatant of culture liquid as an effective antimicrobial agent noticeably simplifies and reduces the cost of the technology of its obtaining.

  20. Data Retention and Anonymity Services

    Science.gov (United States)

    Berthold, Stefan; Böhme, Rainer; Köpsell, Stefan

    The recently introduced legislation on data retention to aid prosecuting cyber-related crime in Europe also affects the achievable security of systems for anonymous communication on the Internet. We argue that data retention requires a review of existing security evaluations against a new class of realistic adversary models. In particular, we present theoretical results and first empirical evidence for intersection attacks by law enforcement authorities. The reference architecture for our study is the anonymity service AN.ON, from which we also collect empirical data. Our adversary model reflects an interpretation of the current implementation of the EC Directive on Data Retention in Germany.

  1. Next Generation Surfactants for Improved Chemical Flooding Technology

    Energy Technology Data Exchange (ETDEWEB)

    Laura Wesson; Prapas Lohateeraparp; Jeffrey Harwell; Bor-Jier Shiau

    2012-05-31

    The principle objective of this project was to characterize and test current and next generation high performance surfactants for improved chemical flooding technology, focused on reservoirs in the Pennsylvanian-aged (Penn) sands. In order to meet this objective the characteristic curvatures (Cc) of twenty-eight anionic surfactants selected for evaluation for use in chemical flooding formulations were determined. The Cc values ranged from -6.90 to 2.55 with the majority having negative values. Crude oil samples from nine Penn sand reservoirs were analyzed for several properties pertinent to surfactant formulation for EOR application. These properties included equivalent alkane carbon numbers, total acid numbers, and viscosity. The brine samples from these same reservoirs were analyzed for several cations and for total dissolved solids. Surfactant formulations were successfully developed for eight reservoirs by the end of the project period. These formulations were comprised of a tertiary mixture of anionic surfactants. The identities of these surfactants are considered proprietary, but suffice to say the surfactants in each mixture were comprised of varying chemical structures. In addition to the successful development of surfactant formulations for EOR, there were also two successful single-well field tests conducted. There are many aspects that must be considered in the development and implementation of effective surfactant formulations. Taking into account these other aspects, there were four additional studies conducted during this project. These studies focused on the effect of the stability of surfactant formulations in the presence of polymers with an associated examination of polymer rheology, the effect of the presence of iron complexes in the brine on surfactant stability, the potential use of sacrificial agents in order to minimize the loss of surfactant to adsorption, and the effect of electrolytes on surfactant adsorption. In these last four studies

  2. Interactions of Phospholipid Vesicles with Cationic and Anionic Oligomeric Surfactants.

    Science.gov (United States)

    Chen, Yao; Qiao, Fulin; Fan, Yaxun; Han, Yuchun; Wang, Yilin

    2017-07-27

    This work studied the interactions of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) with cationic ammonium surfactants and anionic sulfate or sulfonate surfactants of different oligomeric degrees, including cationic monomeric DTAB, dimeric C 12 C 3 C 12 Br 2 , and trimeric DDAD as well as anionic monomeric SDS, dimeric C 12 C 3 C 12 (SO 3 ) 2 , and trimeric TED-(C 10 SO 3 Na) 3 . The partition coefficient P of these surfactants between the DOPC vesicles and water was determined with isothermal titration microcalorimetry (ITC) by titrating concentrated DOPC solution into the monomer solution of these surfactants. It was found that the P value increases with the increase of the surfactant oligomeric degree. Moreover, the enthalpy change and the Gibbs free energy for the transition of these surfactants from water into the DOPC bilayer become more negative with increasing the oligomeric degree. Meanwhile, the calcein release experiment proves that the surfactant with a higher oligomeric degree shows stronger ability of changing the permeability of the DOPC vesicles. Furthermore, the solubilization of the DOPC vesicles by these oligomeric surfactants was studied by ITC, turbidity, and dynamic light scattering, and thus the phase boundaries for the surfactant/lipid mixtures have been determined. The critical surfactant to lipid ratios for the onset and end of the solubilization for the DOPC vesicles derived from the phase boundaries decrease remarkably with increasing the oligomeric degree. Overall, the surfactant with a larger oligomerization degree shows stronger ability in incorporating into the lipid bilayer, altering the membrane permeability and solubilizing lipid vesicles, which provides comprehensive understanding about the effects of structure and shape of oligomeric surfactant molecules on lipid-surfactant interactions.

  3. Micellization and microstructural studies between amphiphilic drug ibuprofen with non-ionic surfactant in aqueous urea solution

    International Nuclear Information System (INIS)

    Rub, Malik Abdul; Azum, Naved; Kumar, Dileep; Asiri, Abdullah M.; Marwani, Hadi M.

    2014-01-01

    Highlights: • Micellization behavior of (ibuprofen + non-ionic surfactant) mixtures has been investigated. • Ion–dipole type of interaction between ibuprofen drug and non-ionic surfactant. • The negative β values propose attractive interactions between the components. • Stern–Volmer binding constants (K sv ) and dielectric constant of mixed systems have also been evaluated. • The results have applicability in drug delivery. - Abstract: Herein, we have accounted for the interaction between a non-steroidal anti-inflammatory drug ibuprofen (IBF) and non-ionic surfactant polyethoxyglycol t-octylphenyl ether (TX-100 (4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol) and TX-114 ((1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol)), in aqueous urea solutions using tensiometric and fluorimetric techniques at T = 298.15 K. Surface tension measurements were carried out to evaluate the critical micelle concentrations (cmc) of the drug and surfactant as well as their mixtures of varying compositions. An increase in the surface charge of the micelles was observed with the addition of urea followed by halt of micelles formation. Various physicochemical parameters, such as, cmc values of the mixture, micellar mass fraction (X 1 Rub ) of surfactants (TX-100/TX-114), interaction parameters (β) at the monolayer air–water interface and in bulk solutions, different thermodynamic parameters and activity coefficients (f 1 m ,f 2 m ) for the non-ionic surfactant and drug in the mixed micelles, were determined by using the approach of Clint, of Rubingh, and of Rosen. All results identified synergism and attractive interactions in the mixed systems of (drug–surfactant) mixtures and showed effective involvement of the non-ionic surfactant (TX-100/TX-114) component in the mixture. Micelle aggregation numbers (N agg ), evaluated by using steady-state fluorescence quenching studies, suggest that the contribution of non-ionic surfactant was always more than that of

  4. Retention of in-situ surface modified silica nanoparticles for carbon dioxide foam stabilization in sandpack

    Science.gov (United States)

    Adil, Muhammad

    2014-10-01

    Nanoparticle-stabilized CO2 foams have been used for mobility control for CO2 flooding; however, raw nanosilica particles which are hydrophilic in nature tend to develop unstable CO2 foam under certain reservoir conditions. The unstable foam leads to particles aggregation resulting in complete retention while propagating in a long distance, deep into the reservoir. This can be avoided by the application of a particular coating of a specific surfactant, polymer or their combination to the surface of the nanoparticles. The in-situ surface activation of unmodified SiO2 nanoparticles by interaction with mixed surfactant (TX100:SDBS) in aqueous media has been studied with extensive experiments using variable volumetric ratios. The retention of in-situ surface-modified nanoparticles was evaluated by the injection of the dispersion of nanoparticles through a sandpack. The loading of nanoparticles in dispersion was ranging from concentrated (5 wt %) to dilute (0.1 wt %). Effluent nanoparticles concentration histories were measured to determine the retained particles in the sandpack. Little retention (injected over two pore volumes) was attained for 0.5% SiO2 and volumetric ratio of 2:1 (TX100:SDBS). These results were concluded in terms of surface charges, adsorption isotherm, surface adsorption, and DLVO theory between particles and rock.

  5. African American College Student Retention and the Ecological Psychology of Historically Black Colleges.

    Science.gov (United States)

    Brown, M. Christopher, II

    1998-01-01

    Discusses the dominant historic, economic, political, and social issues which affect the retention of African American college students through studies on ecological psychology. Considers the behaviors demonstrated by historically Black colleges which translate into effective retention policies or practices for predominantly White institutions.…

  6. Surfactant protein B inhibits secretory phospholipase A2 hydrolysis of surfactant phospholipids

    Science.gov (United States)

    Grier, Bonnie L.; Waite, B. Moseley; Veldhuizen, Ruud A.; Possmayer, Fred; Yao, Li-Juan; Seeds, Michael C.

    2012-01-01

    Hydrolysis of surfactant phospholipids (PL) by secretory phospholipases A2 (sPLA2) contributes to surfactant damage in inflammatory airway diseases such as acute lung injury/acute respiratory distress syndrome. We and others have reported that each sPLA2 exhibits specificity in hydrolyzing different PLs in pulmonary surfactant and that the presence of hydrophilic surfactant protein A (SP-A) alters sPLA2-mediated hydrolysis. This report tests the hypothesis that hydrophobic SP-B also inhibits sPLA2-mediated surfactant hydrolysis. Three surfactant preparations were used containing varied amounts of SP-B and radiolabeled tracers of phosphatidylcholine (PC) or phosphatidylglycerol (PG): 1) washed ovine surfactant (OS) (pre- and postorganic extraction) compared with Survanta (protein poor), 2) Survanta supplemented with purified bovine SP-B (1–5%, wt/wt), and 3) a mixture of dipalmitoylphosphatidylcholine (DPPC), 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), and 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) (DPPC:POPC:POPG, 40:40:20) prepared as vesicles and monomolecular films in the presence or absence of SP-B. Hydrolysis of PG and PC by Group IB sPLA2 (PLA2G1A) was significantly lower in the extracted OS, which contains SP-B, compared with Survanta (P = 0.005), which is SP-B poor. Hydrolysis of PG and PC in nonextracted OS, which contains all SPs, was lower than both Survanta and extracted OS. When Survanta was supplemented with 1% SP-B, PG and PC hydrolysis by PLA2G1B was significantly lower (P hydrolysis by both PLA2G1B and Group IIA sPLA2 (PLA2G2A). In films, PLA2G1B hydrolyzed surfactant PL monolayers at surface pressures ≤30 mN/m (P hydrolysis can occur. These results suggest the hydrophobic SP, SP-B, protects alveolar surfactant PL from hydrolysis mediated by multiple sPLA2 in both vesicles (alveolar subphase) and monomolecular films (air-liquid interface). PMID:22037357

  7. Biocompatible microemulsions of dicephalic aldonamide-type surfactants: formulation, structure and temperature influence.

    Science.gov (United States)

    Wilk, Kazimiera A; Zielińska, Katarzyna; Hamerska-Dudra, Agnieszka; Jezierski, Adam

    2009-06-01

    The temperature effects upon microemulsion systems composed of dicephalic N-dodecyl-N,N-bis[(3-D-aldonylamido)propyl]amines C12-DX (gluconyl GA or lactobionyl LA)/iso-butanol/hydrophilic (diethylene glycol monoethyl ether) or hydrophobic (iso-octane) oils/water were investigated by evaluating isotropic area magnitudes in the pseudoternary phase diagrams, as well as droplet characteristics by electron paramagnetic resonance (EPR) and dynamic light scattering (DLS) spectroscopies at 25, 40 and 55 degrees C. We concluded that in the examined systems a cosurfactant, such as middle-chain alcohol, was needed to obtain large mesophase isotropic areas. The phase behavior and structure of the examined systems were temperature insensitive but they were intimately determined by the nature of the C12-DX and the polarity of the oil phase. By adjusting the nature of the oil, as well as the surfactant hydrophilicity, the performed isotropic systems containing low amounts of nonaggressive surfactant could be formulated successfully. Interfacial properties and the dynamic structure of the surfactant/cosurfactant monolayer were studied by the spin probe technique using the 16-doxylstearic acid methyl ester (16-DSE) as the appropriate probe. The polarity of the interface was not affected by temperature but the interface rigidity was dependent upon the nature of the surfactant and oil as well as on temperature. The size of the dispersed domains, evaluated by dynamic light scattering (DLS), was found to be a function of temperature, surfactant content and type of additives. The investigated o/w microemulsions (i.e., ranging from 3.0 to 8.8 nm) constituted promising templates for a variety of syntheses of nanostructures with small size and high-capacity solubilizing media.

  8. Moving liquid surfactant as a way of assessing the properties of surfactant, liquids and surfaces

    Science.gov (United States)

    Titov, A. O.; Titov, O. P.; Titov, M. O.; Karbainov, A. N.

    2011-04-01

    In the study of surface phenomena of the main and only instrumentally-defined parameters are surface tension and wetting angle, including in the field of nanotechnology. These indicators were introduced more than 200 years ago, and any new inventions in this field was no more. The university developed a new method and device for determining the surface activity. The basis of the method and device is the use of video cameras to record the droplet size and changes on the surface of the liquid layer of known thickness from the impact of drops of surfactant (surfactant). Committed changes are then processed using computer software and calculated parameters, which can be characterized by a surfactant and surface properties, which is fluid and very liquid. Determine the surface tension or contact angle is not necessary. Measures of surface activity using the method and device are: The amount of fluid that can move one kilogram of surfactant. The value of this index varies from tens of nanometers to hundreds of thousands of units. The indicator can be converted to energy units, joules. The amount of fluid confined by a surface per unit time is calculated based on the first indicator, complements the characterization of surfactant and may be an indicator of surface characteristics and fluid. Propagation speed of the capillary and microwaves. This indicator complements the first two.

  9. Hydrogels of sodium alginate in cationic surfactants: Surfactant dependent modulation of encapsulation/release toward Ibuprofen.

    Science.gov (United States)

    Jabeen, Suraya; Chat, Oyais Ahmad; Maswal, Masrat; Ashraf, Uzma; Rather, Ghulam Mohammad; Dar, Aijaz Ahmad

    2015-11-20

    The interaction of cetyltrimethylammoium bromide (CTAB) and its gemini homologue (butanediyl-1,4-bis (dimethylcetylammonium bromide), 16-4-16 with biocompatible polymer sodium alginate (SA) has been investigated in aqueous medium. Addition of K2CO3 influences viscoelastic properties of surfactant impregnated SA via competition between electrostatic and hydrophobic interactions. Viscosity of these polymer-surfactant systems increases with increase in concentration of K2CO3, and a cryogel is formed at about 0.5M K2CO3 concentration. The thermal stability of gel (5% SA+0.5M K2CO3) decreases with increase in surfactant concentration, a minimum is observed with increase in 16-4-16 concentration. The impact of surfactant addition on the alginate structure vis-à-vis its drug loading capability and release thereof was studied using Ibuprofen (IBU) as the model drug. The hydrogel with 16-4-16 exhibits higher IBU encapsulation and faster release in comparison to the one containing CTAB. This higher encapsulation-cum-faster release capability has been related to micelle mediated solubilization and greater porosity of the hydrogel with gemini surfactant. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Identification of novel fluorinated surfactants in aqueous film forming foams and commercial surfactant concentrates.

    Science.gov (United States)

    D'Agostino, Lisa A; Mabury, Scott A

    2014-01-01

    Recent studies comparing the results of total organofluorine-combustion ion chromatography (TOF-CIC) to targeted analysis of perfluoroalkyl and polyfluoroalkyl substances (PFASs) by liquid chromatography tandem mass spectrometry (LC-MS/MS) have shown that a significant yet variable portion of the total organofluorine in environmental and biological samples is in the form of unknown PFASs. A portion of this unknown organofluorine likely originates in proprietary fluorinated surfactants not included in LC-MS/MS analyses and not fully characterized by the environmental science community, which may enter the environment through use in aqueous film forming foams (AFFFs) for firefighting. Contamination of water, biota, and soils with various PFASs due to AFFF deployment has been documented. Ten fluorinated AFFF concentrates, 9 of which were obtained from fire sites in Ontario, Canada, and two commercial fluorinated surfactant concentrates were characterized in order to identify novel fluorinated surfactants. Mixed-mode ion exchange solid phase extraction (SPE) fractionated fluorinated surfactants based on ionic character. High resolution mass spectrometry assigned molecular formulas to fluorinated surfactant ions, while collision induced dissociation (CID) spectra assisted structural elucidation. LC-MS/MS detected isomers and low abundance fluorinated chain lengths. In total, 12 novel and 10 infrequently reported PFAS classes were identified in fluorinated chain lengths from C3 to C15 for a total of 103 compounds. Further research should examine the environmental fate and toxicology of these PFASs, especially their potential as perfluoroalkyl acid (PFAA) precursors.

  11. Skill Retention and Relearning--A Proposed Cyclical Model.

    Science.gov (United States)

    Ginzburg, S.; Dar-El, E. M.

    2000-01-01

    The relationship between relearning and retention was examined during refresher training for 53 Israeli soldiers operating an electronic system. The longer the training interval, the lower the operator's performance level. Partial simulation was suitable for retraining in complex tasks. A cyclical behavior model of learning, forgetting, and…

  12. Increased preventive practices lead to greater tooth retention.

    Science.gov (United States)

    Kressin, N R; Boehmer, U; Nunn, M E; Spiro, A

    2003-03-01

    Prior research has rarely examined the impact of ADA-recommended preventive practices on tooth retention. We hypothesized that better oral hygiene leads to increased tooth retention. We examined the association of cross-sectional and long-term assessments of preventive practices, as well as various combinations of hygiene practices, with tooth retention. Among 736 male participants in the VA Dental Longitudinal Study, we utilized cross-sectional and longitudinal self-reports of toothbrushing, dental floss use, annual prophylaxis, and combinations of such behaviors, and examined their association with clinically assessed numbers of teeth. Baseline and long-term hygiene behaviors (except brushing) were associated with an increased baseline number of teeth and decreased subsequent tooth loss. Use of multiple hygiene behaviors was associated with greater tooth retention, cross-sectionally and longitudinally. Adherence to ADA recommendations for preventive care leads to better oral health, and consistently practicing preventive behaviors over the long term confers greater benefits than doing so over the short term.

  13. Fission gas retention and axial expansion of irradiated metallic fuel

    International Nuclear Information System (INIS)

    Fenske, G.R.; Emerson, J.E.; Savoie, F.E.; Johanson, E.W.

    1986-05-01

    Out-of-reactor experiments utilizing direct electrical heating and infrared heating techniques were performed on irradiated metallic fuel. The results indicate accelerated expansion can occur during thermal transients and that the accelerated expansion is driven by retained fission gases. The results also demonstrate gas retention and, hence, expansion behavior is a function of axial position within the pin

  14. O/W emulsions stabilised by both low molecular weight surfactants and colloidal particles: The effect of surfactant type and concentration.

    Science.gov (United States)

    Pichot, R; Spyropoulos, F; Norton, I T

    2010-12-01

    The stability against coalescence of O/W emulsions in the presence of both surfactants and colloidal particles was investigated. In particular the effect of the surfactant type and concentration in these emulsifier mixtures on the O/W emulsions' stability was studied. Two types of surfactants were selected; those that have the ability to stabilise O/W emulsions on their own (O/W surfactants) and those that cannot (W/O surfactants). Tween 60 and Sodium Caseinate were selected as the O/W surfactants and lecithin as the W/O surfactant. Oil-in-water emulsions prepared with both particles and any of the three surfactants were stable against coalescence but, depending on the type of surfactant, the behaviour of the systems was found to depend on surfactant concentration. The droplet sizes of emulsions stabilised by mixed emulsifier systems containing low concentrations of O/W surfactants (Tween 60 or Sodium Caseinate) were smaller than those solely stabilised by either the surfactant or particles alone. At intermediate O/W surfactants concentrations, the droplet sizes of the emulsions increased. Further increases in the O/W surfactants' concentration, resulted in the complete removal of particles from the interface with the system now behaving as a surfactant-only stabilised emulsion. The behaviour of emulsions stabilised by emulsifier mixtures containing W/O surfactants was not dependent on the concentration of surfactant: no removal of particles was observed. Copyright © 2010 Elsevier Inc. All rights reserved.

  15. On the formation of new reverse micelles: a comparative study of benzene/surfactants/ionic liquids systems using UV-visible absorption spectroscopy and dynamic light scattering.

    Science.gov (United States)

    Falcone, R Darío; Correa, N Mariano; Silber, Juana J

    2009-09-15

    The microenvironment of the polar core generated in different ionic liquid reverse micelle (IL RM) systems were investigated using the solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) as an absorption probe and dynamic light scattering (DLS) technique. The novel RM systems consist of two different ILs--1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmimTf2N)--sequestrated by two different surfactants--Triton X-100 (TX-100) and benzyl-n-hexadecyldimethylammonium chloride (BHDC)--in order to make IL/surfactant/benzene RMs. The effect of the variation of Ws (Ws=[IL]/[surfactant]) on the QB spectroscopy was used to characterize these nonaqueous RMs. DLS results confirm the formation of these IL RM systems because increasing Ws increases the droplet sizes. Moreover it is demonstrated that the structure of the sequestrated ILs depends strongly on the type of surfactant use to create the RMs.

  16. Interactions of bovine serum albumin with cationic imidazolium and quaternary ammonium gemini surfactants: effects of surfactant architecture.

    Science.gov (United States)

    Zhou, Ting; Ao, Mingqi; Xu, Guiying; Liu, Teng; Zhang, Juan

    2013-01-01

    The interactions of BSA with a series of cationic imidazolium gemini surfactants ([C(n)-s-C(n)im]Br(2), n=10, 12, 14, s=2, 4, 6), quaternary ammonium surfactants (C(12)C(2)C(12)), and their corresponding monomers ([C(12)mim]Br and DTAB) are investigated by fluorescence using pyrene as a molecular probe, synchronous fluorescence, circular dichroism (CD), and UV-visible absorption spectra. These surfactants are used to elucidate the effects of surfactant hydrophilic head group, spacer length, and hydrophobic chain length on the conformation of BSA. The results of fluorescence spectra and CD show that the imidazolium gemini surfactants with shorter spacers or with longer hydrophobic chains have a larger effect on BSA unfolding, and the imidazolium gemini surfactant interacts with BSA more strongly than its corresponding monomer and the quaternary ammonium gemini surfactant. These conclusions have been confirmed by the binding constants (K(a)) and binding sites (n) for the BSA/surfactant system. Stern-Volmer quenching constants K(SV) of cationic surfactants binding to BSA are obtained, indicating that the probable quenching mechanism is initiated by ground-state complex formation rather than by dynamic collision. Moreover, the synchronous fluorescence spectra show that the surfactants mainly interact with tryptophan residues of BSA. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Equilibrium and nonequilibrium behaviour of surfactant systems

    OpenAIRE

    Reissig, Louisa

    2010-01-01

    In binary systems, surfactant molecules can self-assemble into a large variety of structures depending on their chemical structure, concentration and temperature. The properties and stability of the phases, their coexistence regions and the formation of metastable structures is of great importance not only for fundamental understanding, but also for applications in many fields including industry and medicine. This thesis presents studies of the equilibrium and non-equilibrium b...

  18. Rheological Study on ATBS-AM Copolymer-Surfactant System in High-Temperature and High-Salinity Environment

    Directory of Open Access Journals (Sweden)

    Muhammad Shahzad Kamal

    2013-01-01

    Full Text Available Experimental studies were conducted to evaluate the rheological properties of surfactant-polymer (SP system. This SP system consists of a copolymer of acrylamide (AM and acrylamido tertiary butyl sulfonate (ATBS and sodium dodecyl sulphate (SDS surfactant. Effects of surfactant concentration, temperature, polymer concentration, and salinity on rheological properties of SP system were investigated by means of oscillation and shear measurements. Comparison with classical partially hydrolyzed polyacrylamide (HPAM was made. For the same temperature range, the viscosity drop for HPAM was about four times higher than the viscosity drop for ATBS-AM copolymer. In deionized water, viscosity of both polymers and SP systems was very high as compared to viscosity in saline water. Viscosity reduction of ATBS-AM copolymer was higher for salts having divalent cations. The SP system showed precipitation in presence of divalent cations. It worked well with monovalent cations even at relatively high salinities. The addition of 0.1% surfactant to the polymer resulted in a 60% decrease in the viscosity. Some interfacial rheological experiments were also carried out to investigate the behaviors on the interface between SP solutions and oil. Addition of 0.1% surfactant showed a 65% decrease in G′ at SP solution-oil interface. SP system consisting of ATBS-AM and SDS showed better performance at high temperature compared to HPAM-SDS system. Due to precipitation, the SP system should be restricted to environment having low divalent cations.

  19. Role of anionic and cationic surfactants on the structural and dielectric properties of ZrO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, Gaganpreet Kaur; Kumar, Rajesh, E-mail: rajeshbaboria@gmail.com

    2017-01-15

    Highlights: • Synthesis of Zirconia nanoparticles with and without surfactants by co- precipitation method. • Surface modification of ZrO{sub 2} nanoparticles. • Phase transition with different concentration of surfactants. • Dielectric behavior of bare, CTAB assisted and SDS assisted ZrO{sub 2} nanoparticles. - Abstract: In the present paper, we report the synthesis of Cetyltrimethylammonium Bromide (CTAB) and Sodium dodecyl sulfate (SDS) assisted Zirconia (ZrO{sub 2}) nanoparticles by co-precipitation method. The effect of surfactant concentration on the structural and dielectric properties has been extensively studied. X-ray diffraction studies reveal the formation of tetragonal phase in the ZrO{sub 2} nanoparticles prepared by lower CTAB concentration. However, for higher concentration of CTAB some traces of monoclinic phase appeared along with tetragonal phase. SDS assisted nanoparticles shows crystalline tetragonal phase with lower concentration of SDS and amorphous nature with higher concentrations of SDS. FTIR results show the presence of Zr–O symmetrical stretching vibrations at tetrahedral site. The dielectric properties of all samples have been studied from 10 Hz to 1 MHz, revealing the low value of dielectric constant with CTAB and very high value with SDS as compared to bare ZrO{sub 2} nanoparticles. The dielectric behaviour of the bare and surfactant assisted nanoparticles has been correlated with the phase transition, size of nanoparticles and the nature of surfactants.

  20. Rosin Surfactant QRMAE Can Be Utilized as an Amorphous Aggregate Inducer: A Case Study of Mammalian Serum Albumin.

    Directory of Open Access Journals (Sweden)

    Mohd Ishtikhar

    Full Text Available Quaternary amine of diethylaminoethyl rosin ester (QRMAE, chemically synthesized biocompatible rosin based cationic surfactant, has various biological applications including its use as a food product additive. In this study, we examined the amorphous aggregation behavior of mammalian serum albumins at pH 7.5, i.e., two units above their isoelectric points (pI ~5.5, and the roles played by positive charge and hydrophobicity of exogenously added rosin surfactant QRMAE. The study was carried out on five mammalian serum albumins, using various spectroscopic methods, dye binding assay, circular dichroism and electron microscopy. The thermodynamics of the binding of mammalian serum albumins to cationic rosin modified surfactant were established using isothermal titration calorimetry (ITC. It was observed that a suitable molar ratio of protein to QRMAE surfactant enthusiastically induces amorphous aggregate formation at a pH above two units of pI. Rosin surfactant QRMAE-albumins interactions revealed a unique interplay between the initial electrostatic and the subsequent hydrophobic interactions that play an important role towards the formation of hydrophobic interactions-driven amorphous aggregate. Amorphous aggregation of proteins is associated with varying diseases, from the formation of protein wine haze to the expansion of the eye lenses in cataract, during the expression and purification of recombinant proteins. This study can be used for the design of novel biomolecules or drugs with the ability to neutralize factor(s responsible for the aggregate formation, in addition to various other industrial applications.

  1. Transit ridership, reliability, and retention.

    Science.gov (United States)

    2008-10-01

    This project explores two major components that affect transit ridership: travel time reliability and rider : retention. It has been recognized that transit travel time reliability may have a significant impact on : attractiveness of transit to many ...

  2. EA Shuttle Document Retention Effort

    Science.gov (United States)

    Wagner, Howard A.

    2010-01-01

    This slide presentation reviews the effort of code EA at Johnson Space Center (JSC) to identify and acquire databases and documents from the space shuttle program that are adjudged important for retention after the retirement of the space shuttle.

  3. Dynamics of contracting surfactant-covered filaments

    Science.gov (United States)

    Kamat, Pritish; Thete, Sumeet; Xu, Qi; Basaran, Osman

    2013-11-01

    When drops are produced from a nozzle, a thin liquid thread connects the primary drop that is about to form to the rest of the liquid in the nozzle. Often, the thread becomes disconnected from both the primary drop and the remnant liquid mass hanging from the nozzle and thereby gives rise to a free filament. Due to surface tension, the free filament then contracts or recoils. During recoil, the filament can either contract into a single satellite droplet or break up into several small satellites. Such satellite droplets are undesirable in applications where they can, for example, cause misting in a manufacturing environment and mar product quality in ink-jet printing. In many applications, the filaments are coated with a monolayer of surfactant. In this work, we study the dynamics of contraction of slender filaments of a Newtonian fluid that are covered with a monolayer of surfactant when the surrounding fluid is a passive gas. Taking advantage of the fact that the filaments are long and slender, we use a 1D-slender-jet approximation of the governing system of equations consisting of the Navier-Stokes system and the convection-diffusion equation for surfactant transport. We solve the 1D system of equations by a finite element based numerical method.

  4. phosphorus retention data and metadata

    Science.gov (United States)

    phosphorus retention in wetlands data and metadataThis dataset is associated with the following publication:Lane , C., and B. Autrey. Phosphorus retention of forested and emergent marsh depressional wetlands in differing land uses in Florida, USA. Wetlands Ecology and Management. Springer Science and Business Media B.V;Formerly Kluwer Academic Publishers B.V., GERMANY, 24(1): 45-60, (2016).

  5. Grade Retention and Unobserved Heterogeneity

    OpenAIRE

    Robert J. Gary-Bobo; Marion Gousse; Jean-Marc Robin

    2014-01-01

    We study the treatment effect of grade retention using a panel of French junior high-school students, taking unobserved heterogeneity and the endogeneity of grade repetitions into account. We specify a multistage model of human-capital accumulation with a finite number of types representing unobserved individual characteristics. Class-size and latent student-performance indices are assumed to follow finite mixtures of normal distributions. Grade retention may increase or decrea...

  6. Influence of metacide - surfactant complexes on agricultural crops

    Directory of Open Access Journals (Sweden)

    Orynkul Esimova

    2014-12-01

    Full Text Available The complexes based on surfactants and polyhexamethyleneguanidine hydrochloride (metacide are important for agriculture. This paper considers compositions of known bactericidal metacide with different surfactants: anionic surfactant sodium dodecylsulphate (DDSNa and nonionic surfactant Tween 80 (monooleate of oxyethylenated anhydrosorbitols. The effect of individual components and associates of metacide and surfactants on productivity and infection of cereals was studied. According to the study, the highest productivity and infection rate were shown by the associate of metacide and Tween-80. At concentration of Tween-80 in aqueous solution equal to 0.001% in combination with metacide, efficiency was 98% at 0% infection. The surface tension and the wetting of metacide, DDSNa, Tween-80, and associates of metacide with surfactants were studied. In comparison with individual components, metacide-DDSNa and metacide-Tween-80 associates have higher surface activity.

  7. Surfactant protein A and surfactant protein D variation in pulmonary disease

    DEFF Research Database (Denmark)

    Sørensen, Grith Lykke; Husby, Steffen; Holmskov, Uffe

    2007-01-01

    Surfactant proteins A (SP-A) and D (SP-D) have been implicated in pulmonary innate immunity. The proteins are host defense lectins, belonging to the collectin family which also includes mannan-binding lectin (MBL). SP-A and SP-D are pattern-recognition molecules with the lectin domains binding...... lavage and blood have indicated associations with a multitude of pulmonary inflammatory diseases. In addition, accumulating evidence in mouse models of infection and inflammation indicates that recombinant forms of the surfactant proteins are biologically active in vivo and may have therapeutic potential...... in controlling pulmonary inflammatory disease. The presence of the surfactant collectins, especially SP-D, in non-pulmonary tissues, such as the gastrointestinal tract and genital organs, suggest additional actions located to other mucosal surfaces. The aim of this review is to summarize studies on genetic...

  8. Antibacterial Activities of Surfactants in the Laundry Detergents and Isolation of the Surfactant Resistant Aquatic Bacteria.

    Science.gov (United States)

    Maehara, Yoko; Miyoshi, Shin-Ichi

    2017-01-01

     Linear alkylbenzene sulfonate (LAS) and polyoxyethylene lauryl ether (POLE) are major surfactants contained in the laundry detergents. In the present study, the antibacterial activities of the surfactants to aquatic microorganisms were compared. When freshwater samples from a small river in Okayama city were treated with each of the surfactants, only LAS showed the significant antibacterial activity. Several strains, which survived after the treatment with 2.0% LAS, were isolated and identified by sequencing of 16S rDNA. All strains were classified into the family Enterobacteriaceae. However, this family was not a major member of the aquatic microflora, suggesting that the bacteria in Enterobacteriaceae have a common property of LAS-resistance in the river water.

  9. Micelle-vesicle-micelle transition in aqueous solution of anionic surfactant and cationic imidazolium surfactants: Alteration of the location of different fluorophores.

    Science.gov (United States)

    Dutta, Rupam; Ghosh, Surajit; Banerjee, Pavel; Kundu, Sangita; Sarkar, Nilmoni

    2017-03-15

    The presence of different surfactants can alter the physicochemical behaviors of aqueous organized assemblies. In this article, we have investigated the location of hydrophobic molecule (Coumarin 153, C153) and hydrophilic molecule (Rhodamine 6G perchlorate, R6G) during micelle-vesicle-micelle transition in aqueous medium in presence of anionic surfactant, sodium dodecylbenzenesulfonate (SDBS) and cationic imidazolium-based surfactant, 1-alkyl-3-methylimidazolium chloride (C n mimCl; n=12, 16). Initially, the physicochemical properties of anionic micellar solution of SDBS has been investigated in presence of imidazolium-based surfactant, C n mimCl (n=12, 16) in aqueous medium by visual observation, turbidity measurement, zeta potential (ζ), dynamics light scattering (DLS), and transmission electron microscopy (TEM). Zeta potential (ζ) measurement clearly indicates that the incorporation efficiency of C 16 mimCl in SDBS micelle is better than the other one due to the involvement of strong hydrophobic as well as electrostatic interaction between the two associated molecules. Turbidity and DLS measurements clearly suggest the formation of vesicles over a wide range of concentration. Finally, the rotational motion of C153 and R6G has also been monitored at different mole fractions of C n mimCl in SDBS-C n mimCl (n=12, 16) solution mixtures. The hydrophobic C153 molecules preferentially located in the bilayer region of vesicle, whereas hydrophilic R6G can be solubilized at surface of the bilayer, inner water pool or outer surface of vesicles. It is observed that rotational motion of R6G is altered significantly in SDBS-C n mimCl solution mixtures in presence of different mole fractions of C n mimCl. Additionally, the translational diffusion motion of R6G is monitored using fluorescence correlation spectroscopy (FCS) techniques to get a complete scenario about the location and translational diffusion of R6G. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. The Role of Surfactant in Respiratory Distress Syndrome

    OpenAIRE

    Ma, Christopher Cheng-Hwa; Ma, Sze

    2012-01-01

    The key feature of respiratory distress syndrome (RDS) is the insufficient production of surfactant in the lungs of preterm infants. As a result, researchers have looked into the possibility of surfactant replacement therapy as a means of preventing and treating RDS. We sought to identify the role of surfactant in the prevention and management of RDS, comparing the various types, doses, and modes of administration, and the recent development. A PubMed search was carried out up to March 2012 u...

  11. Molecular characterization of water and surfactant AOT at nanoemulsion surfaces.

    Science.gov (United States)

    Hensel, Jennifer K; Carpenter, Andrew P; Ciszewski, Regina K; Schabes, Brandon K; Kittredge, Clive T; Moore, Fred G; Richmond, Geraldine L

    2017-12-19

    Nanoemulsions and microemulsions are environments where oil and water can be solubilized in one another to provide a unique platform for many different biological and industrial applications. Nanoemulsions, unlike microemulsions, have seen little work done to characterize molecular interactions at their surfaces. This study provides a detailed investigation of the near-surface molecular structure of regular (oil in water) and reverse (water in oil) nanoemulsions stabilized with the surfactant dioctyl sodium sulfosuccinate (AOT). Vibrational sum-frequency scattering spectroscopy (VSFSS) is used to measure the vibrational spectroscopy of these AOT stabilized regular and reverse nanoemulsions. Complementary studies of AOT adsorbed at the planar oil-water interface are conducted with vibrational sum-frequency spectroscopy (VSFS). Jointly, these give comparative insights into the orientation of interfacial water and the molecular characterization of the hydrophobic and hydrophilic regions of AOT at the different oil-water interfaces. Whereas the polar region of AOT and surrounding interfacial water molecules display nearly identical behavior at both the planar and droplet interface, there is a clear difference in hydrophobic chain ordering even when possible surface concentration differences are taken into account. This chain ordering is found to be invariant as the nanodroplets grow by Ostwald ripening and also with substitution of different counterions (Na:AOT, K:AOT, and Mg:AOT) that consequently also result in different sized nanoparticles. The results paint a compelling picture of surfactant assembly at these relatively large nanoemulsion surfaces and allow for an important comparison of AOT at smaller micellar (curved) and planar oil-water interfaces.

  12. Investigation of Polymer-Surfactant and Polymer-Drug-Surfactant Miscibility for Solid Dispersion.

    Science.gov (United States)

    Gumaste, Suhas G; Gupta, Simerdeep Singh; Serajuddin, Abu T M

    2016-09-01

    In a solid dispersion (SD), the drug is generally dispersed either molecularly or in the amorphous state in polymeric carriers, and the addition of a surfactant is often important to ensure drug release from such a system. The objective of this investigation was to screen systematically polymer-surfactant and polymer-drug-surfactant miscibility by using the film casting method. Miscibility of the crystalline solid surfactant, poloxamer 188, with two commonly used amorphous polymeric carriers, Soluplus® and HPMCAS, was first studied. Then, polymer-drug-surfactant miscibility was determined using itraconazole as the model drug, and ternary phase diagrams were constructed. The casted films were examined by DSC, PXRD and polarized light microscopy for any crystallization or phase separation of surfactant, drug or both in freshly prepared films and after exposure to 40°C/75% RH for 7, 14, and 30 days. The miscibility of poloxamer 188 with Soluplus® was <10% w/w, while its miscibility with HPMCAS was at least 30% w/w. Although itraconazole by itself was miscible with Soluplus® up to 40% w/w, the presence of poloxamer drastically reduced its miscibility to <10%. In contrast, poloxamer 188 had minimal impact on HPMCAS-itraconazole miscibility. For example, the phase diagram showed amorphous miscibility of HPMCAS, itraconazole, and poloxamer 188 at 54, 23, and 23% w/w, respectively, even after exposure to 40°C/75% RH for 1 month. Thus, a relatively simple and practical method of screening miscibility of different components and ultimately physical stability of SD is provided. The results also identify the HPMCAS-poloxamer 188 mixture as an optimal surface-active carrier system for SD.

  13. [Retention and biomechanics of retentive complexes. 3. The Kratochvil school and current retentive complexes].

    Science.gov (United States)

    Enrique Fernández, M; Jacques Grimonster, L

    1989-04-01

    The authors analyse the biomechanical bases of the Kratochvil "retentive complex" and show how they have induced the nowadays north-american propositions (RPI & RPA). They compare them to the european ones (Nally-Martinet).

  14. The Pulmonary Surfactant: Impact of Tobacco Smoke and Related Compounds on Surfactant and Lung Development

    Directory of Open Access Journals (Sweden)

    Scott J Elliott

    2004-03-01

    Full Text Available Abstract Cigarette smoking, one of the most pervasive habits in society, presents many well established health risks. While lung cancer is probably the most common and well documented disease associated with tobacco exposure, it is becoming clear from recent research that many other diseases are causally related to smoking. Whether from direct smoking or inhaling environmental tobacco smoke (ETS, termed secondhand smoke, the cells of the respiratory tissues and the lining pulmonary surfactant are the first body tissues to be directly exposed to the many thousands of toxic chemicals in tobacco. Considering the vast surface area of the lung and the extreme attenuation of the blood-air barrier, it is not surprising that this organ is the primary route for exposure, not just to smoke but to most environmental contaminants. Recent research has shown that the pulmonary surfactant, a complex mixture of phospholipids and proteins, is the first site of defense against particulates or gas components of smoke. However, it is not clear what effect smoke has on the surfactant. Most studies have demonstrated that smoking reduces bronchoalveolar lavage phospholipid levels. Some components of smoke also appear to have a direct detergent-like effect on the surfactant while others appear to alter cycling or secretion. Ultimately these effects are reflected in changes in the dynamics of the surfactant system and, clinically in changes in lung mechanics. Similarly, exposure of the developing fetal lung through maternal smoking results in postnatal alterations in lung mechanics and higher incidents of wheezing and coughing. Direct exposure of developing lung to nicotine induces changes suggestive of fetal stress. Furthermore, identification of nicotinic receptors in fetal lung airways and corresponding increases in airway connective tissue support a possible involvement of nicotine in postnatal asthma development. Finally, at the level of the alveoli of the lung

  15. Nanoparticle-enabled delivery of surfactants in porous media.

    Science.gov (United States)

    Nourafkan, Ehsan; Hu, Zhongliang; Wen, Dongsheng

    2018-06-01

    The adsorption of surfactants on the reservoir rocks surface is a serious issue in many energy and environment related areas. Learning from the concept of drug delivery in the nano-medicine field, this work proposes and validates the concept of using nanoparticles to deliver a mixture of surfactants into a porous medium. TiO 2 nanoparticles (NPs) are used as carriers for a blend of surfactants mixtures including anionic alkyl aryl sulfonic acid (AAS) and nonionic alcohol ethoxylated (EA) at the optimum salinity and composition conditions. The transport of NPs through a core sample of crushed sandstone grains and the adsorption of surfactants are evaluated. By using TiO 2 NPs, the adsorption of surfactant molecules can be significantly reduced, i.e. half of the initial adsorption value. The level of surfactant adsorption reduction is related to the NPs transport capability through the porous medium. An application study shows that comparing to surfactant flooding alone, the total oil recovery can be increased by 7.81% of original oil in place (OOIP) by using nanoparticle bonded surfactants. Such work shows the promise of NP as an effective surfactant carrier for sandstone reservoirs, which could have many potential applications in enhanced oil recovery (EOR) and environmental remediation. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Fractal Aggregation in Silica Nanoparticle and Surfactant Composites

    Science.gov (United States)

    Kumar, Sugam; Aswal, V. K.

    2011-07-01

    The role of cationic surfactant on particle aggregation of anionic silica nanoparticles has been studied by small-angle neutron scattering (SANS). We show that the aggregation is characterized by the fractal structure. The fractal dimension is found to be same irrespective of varying the surfactant and its concentration. These results are explained on the basis of that the aggregation of particles mediated by the oppositely charged surfactant micelles between them and governed by the diffusion limited aggregation. Both adsorbed and free micelles coexists and the number of adsorbed micelles does not change with varying surfactant concentration however decreases with the increase in the size of the micelle.

  17. Surfactants have multi-fold effects on skin barrier function.

    Science.gov (United States)

    Lemery, Emmanuelle; Briançon, Stéphanie; Chevalier, Yves; Oddos, Thierry; Gohier, Annie; Boyron, Olivier; Bolzinger, Marie-Alexandrine

    2015-01-01

    The stratum corneum (SC) is responsible for the barrier properties of the skin and the role of intercorneocyte skin lipids, particularly their structural organization, in controlling SC permeability is acknowledged. Upon contacting the skin, surfactants interact with the SC components leading to barrier damage. To improve knowledge of the effect of several classes of surfactant on skin barrier function at three different levels. The influence of treatments of human skin explants with six non-ionic and four ionic surfactant solutions on the physicochemical properties of skin was investigated. Skin surface wettability and polarity were assessed through contact angle measurements. Infrared spectroscopy allowed monitoring the SC lipid organization. The lipid extraction potency of surfactants was evaluated thanks to HPLC-ELSD assays. One anionic and one cationic surfactant increased the skin polarity by removing the sebaceous and epidermal lipids and by disturbing the organization of the lipid matrix. Another cationic surfactant displayed a detergency effect without disturbing the skin barrier. Several non-ionic surfactants disturbed the lipid matrix organization and modified the skin wettability without any extraction of the skin lipids. Finally two non-ionic surfactants did not show any effect on the investigated parameters or on the skin barrier. The polarity, the organization of the lipid matrix and the lipid composition of the skin allowed describing finely how surfactants can interact with the skin and disturb the skin barrier function.

  18. Inactivation of Herpes Simplex Viruses by Nonionic Surfactants

    Science.gov (United States)

    Asculai, Samuel S.; Weis, Margaret T.; Rancourt, Martha W.; Kupferberg, A. B.

    1978-01-01

    Nonionic surface-active agents possessing ether or amide linkages between the hydrophillic and hydrophobic portions of the molecule rapidly inactivated the infectivity of herpes simplex viruses. The activity stemmed from the ability of nonionic surfactants to dissolve lipid-containing membranes. This was confirmed by observing surfactant destruction of mammalian cell plasma membranes and herpes simplex virus envelopes. Proprietary vaginal contraceptive formulations containing nonionic surfactants also inactivated herpes simplex virus infectivity. This observation suggests that nonionic surfactants in appropriate formulation could effectively prevent herpes simplex virus transmission. Images PMID:208460

  19. Joint project. Retention of radionuclides relevant for final disposal in natural clay rock and saline systems. Subproject 2. Geochemical behavior and transport of radionuclides in saline systems in the presence of repository-relevant organics. Final report

    International Nuclear Information System (INIS)

    Schmeide, Katja; Fritsch, Katharina; Lippold, Holger

    2016-01-01

    The objective of this project was to study the influence of increased salinities on interaction processes in the system radionuclide - organics - clay - aquifer. For this purpose, complexation, redox, sorption, and diffusion studies were performed under variation of the ionic strength (up to 4 mol kg -1 ) and the background electrolyte. The U(VI) complexation by propionate was studied in dependence on ionic strength (up to 4 mol kg -1 NaClO 4 ) by TRLFS, ATR FT-IR spectroscopy, and DFT calculations. An influence of ionic strength on stability constants was detected, depending on the charge of the respective complexes. The conditional stability constants, determined for 1:1, 1:2, and 1:3 complexes at specific ionic strengths, were extrapolated to zero ionic strength. The interaction of the bacteria Sporomusa sp. MT-2.99 and Paenibacillus sp. MT-2.2 cells, isolated from Opalinus Clay, with Pu was studied. The experiments can be divided into such without an electron donor where biosorption is favored and such with addition of Na-pyruvate as an electron donor stimulating also bioreduction processes. Moreover, experiments were performed to study the interactions of the halophilic archaeon Halobacterium noricense DSM-15987 with U(VI), Eu(III), and Cm(III) in 3 M NaCl solutions. Research for improving process understanding with respect to the mobility of multivalent metals in systems containing humic matter was focused on the reversibility of elementary processes and on their interaction. Kinetic stabilization processes in the dynamics of humate complexation equilibria were quantified in isotope exchange studies. The influence of high salinity on the mobilizing potential of humic-like clay organics was systematically investigated and was described by modeling. The sorption of Tc(VII)/Tc(IV) onto the iron(II)-containing minerals magnetite and siderite was studied by means of batch sorption experiments, ATR FT-IR and X-ray absorption spectroscopy. The strong Tc retention at

  20. Perfluorinated surfactants in surface and drinking waters.

    Science.gov (United States)

    Skutlarek, Dirk; Exner, Martin; Färber, Harald

    2006-09-01

    In this paper recent results are provided of an investigation on the discovery of 12 perfluorinated surfactants (PS) in different surface and drinking waters (Skutlarek et al. 2006 a, Skutlarek et al. 2006 b). In the last years, many studies have reported ubiquitous distribution of this group of perfluorinated chemicals, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in the environment, particularly in wildlife animal and human samples (Giesy and Kannan 2001, Houde et al. 2006, Prevedouros et al. 2006). Perfluorinated surfactants (e.g. PFOS and PFOA) have shown different potentials for reproductory interference and carcinogenity in animal experiments as well as partly long half-lives in humans (Guruge et al. 2006, FSA UK 2006a, FSA UK 2006b, 3M 2005, OECD 2002, Yao and Zhong 2005). They possess compound-dependent extreme recalcitrance against microbiological and chemical degradation and, in addition, they show variable potentials for bioaccumulation in animals and humans (Houde et al. 2006). Surface and drinking water samples were collected from different sampling sites: Surface waters: samples taken from the rivers Rhine, Ruhr, Moehne and some of their tributaries. Further samples were taken from the Rhine-Herne-Canal and the Wesel-Datteln-Canal. Drinking waters: samples taken in public buildings of the Rhine-Ruhr area. After sample clean-up and concentration by solid-phase extraction, the perfluorinated surfactants were determined using HPLC-MS/MS. All measured concentrations (sum of seven mainly detected components) in the Rhine river and its main tributaries (mouths) were determined below 100 ng/L. The Ruhr river (tributary of the Rhine) showed the highest concentration (94 ng/L), but with a completely different pattern of components (PFOA as major component), as compared with the other tributaries and the Rhine river. Further investigations along the Ruhr river showed remarkably high concentrations of PS in the upper reaches of

  1. Influences and mechanisms of surfactants on pyrene biodegradation based on interactions of surfactant with a Klebsiella oxytoca strain.

    Science.gov (United States)

    Zhang, Dong; Zhu, Lizhong; Li, Feng

    2013-08-01

    Surfactant-enhanced bioremediation has been proposed as a promising technology for the treatment of organic polluted soils; however its application has been hindered by the controversial influences and mechanisms of surfactants on the biodegradation of hydrophobic organic compounds. To address this problem, effects of five surfactants on the sorption and biodegradation of pyrene by Klebsiella oxytoca PYR-1, as well as their interactions with bacterial cell surface and membrane lipids were investigated. We found that surfactants enhanced or inhibited pyrene biodegradation depending on their effects on the sorption of pyrene onto bacterial cell, which occurred mainly through modifying cell surface hydrophobicity (such as Tween series surfactants) or disrupting bacterial membrane (such as Triton X-100), respectively. A relatively high positive correlation (Psurfactant, indicating that surfactant-induced sorption played the dominant role during pyrene biodegradation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Individual and group-based learning from complex cognitive tasks: Effects on retention and transfer efficiency

    NARCIS (Netherlands)

    Kirschner, Femke; Paas, Fred; Kirschner, Paul A.

    2009-01-01

    Kirschner, F., Paas, F., & Kirschner, P. (2009). Individual and group-based learning from complex cognitive tasks: Effects on retention and transfer efficiency. Computers in Human Behavior, 25, 306-314.

  3. TOXICITY COMPARISON OF BIOSURFACTANTS AND SYNTHETIC SURFACTANTS USED IN OIL SPILL REMEDIATION TO TWO ESTUARINE SPECIES

    Science.gov (United States)

    The relative environmental toxicities of synthetic and biogenic surfactants used in oil spill remediation efforts are not well understood. Acute and chronic toxicities of three synthetic surfactants and three microbially produced surfactants were determined and compared in this s...

  4. Influence of pulmonary surfactant on in vitro bactericidal activities of amoxicillin, ceftazidime, and tobramycin

    NARCIS (Netherlands)

    A. van 't Veen (Annemarie); J.W. Mouton (Johan); D.A.M.P.J. Gommers (Diederik); J.A.J.W. Kluytmans (Jan); P. Dekkers; B.F. Lachmann (Burkhard)

    1995-01-01

    textabstractThe influence of a natural pulmonary surfactant on antibiotic activity was investigated to assess the possible use of exogenous surfactant as a vehicle for antibiotic delivery to the lung. The influence of surfactant on the bactericidal activity of

  5. Polyoxyethylene alkyl ether carboxylic acids: An overview of a neglected class of surfactants with multiresponsive properties.

    Science.gov (United States)

    Chiappisi, Leonardo

    2017-12-01

    In this work, an overview on aqueous solutions of polyoxyethylene alkyl ether carboxylic acids is given. Unique properties arise from the combination of the nonionic, temperature-responsive polyoxyethylene block with the weakly ionic, pH-responsive carboxylic acid termination in a single surfactant headgroup. Accordingly, this class of surfactant finds broad application across very different sectors. Despite their large use on an industrial and a technical scale, the literature lacks a systematic and detailed characterization of their physico-chemical properties which is provided herein. In addition, a comprehensive overview is given of their self-assembly and interfacial behavior, of their use as colloidal building blocks and for large-scale applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Registered nurse retention strategies in nursing homes: a two-factor perspective.

    Science.gov (United States)

    Hunt, Selina R; Probst, Janice C; Haddock, Kathlyn S; Moran, Robert; Baker, Samuel L; Anderson, Ruth A; Corazzini, Kirsten

    2012-01-01

    As the American population ages and the proportion of individuals over the age of 65 expands, the demand for high-quality nursing home care will increase. However, nursing workforce instability threatens care quality and sustainability in this sector. Despite increasing attention to nursing home staff turnover, far less is known about registered nurse (RN) retention. In this study, the relationships between retention strategies, employee benefits, features of the practice environment, and RN retention were explored. Further, the utility of Herzberg's two-factor theory of motivation as a framework for nursing home retention studies was evaluated. This study was a secondary analysis of the nationally representative 2004 National Nursing Home Survey. The final sample of 1,174 participating nursing homes were either certified by Medicare or Medicaid or licensed by state agencies. We used a weighted multinomial logistic regression using an incremental approach to model the relationships. Although most nursing homes offered some combination of retention programs, the majority of strategies did not have a significant association with the level of RN retention reported by facilities. Director of nursing tenure and other extrinsic factors had the strongest association with RN retention in adjusted analyses. To improve RN retention, organizations may benefit greatly from stabilizing nursing home leadership, especially the director of nursing position. Second, managers of facilities with poor retention may consider adding career ladders for advancement, awarding attendance, and improving employee benefits. As a behavioral outcome of motivation and satisfaction, retention was not explained as expected using Herzberg's two-factor theory.

  7. Experimental contribution to the understanding of the dynamics of spreading of Newtonian fluids: effect of volume, viscosity and surfactant.

    Science.gov (United States)

    Roques-Carmes, Thibault; Mathieu, Vincent; Gigante, Alexandra

    2010-04-01

    The dynamics of drop spreading of glycerol-water mixtures with and without surfactant on hydrophilic glass surfaces has been investigated. The influence of different factors, such as viscosity, drop volume and non-ionic alkyl (8-16) glucoside (Plantacare) surfactant concentration on the number and the nature of the spreading regimes is systematically investigated. More than 25 spreading experiments have been performed in order to obtain clear trends. The results confirm the existence of several spreading regimes for the duration of an experiment (200 s). For each regime, the radius can be expressed by a power law of the form R=Kt(n). Both n and K are necessary to identify the regime. The experimental data are compared with the analytical predictions of the combined theory of spreading. One of the main results of this study is that the nature of the regimes is strongly affected by the drop volume, the viscosity and the surfactant concentration. This behavior is not predicted by the theory. For drop volume less than or equal to 15 microL, a succession of two different regimes which depend on the viscosity and surfactant concentration are observed in the following order: a molecular-kinetic regime followed by a hydrodynamic regime (for high viscosity in the presence of surfactant) or a hydrodynamic regime and lastly a final asymptotic regime corresponding to a long relaxation time to equilibrium (for high viscosity in absence of surfactant and for low viscosity regardless of the presence of surfactant). The spreading follows quantitatively the predictions of the theory. Our results demonstrate that the theory is still valid for low viscosity liquids and in the presence of surfactant. The contact angle for which the crossover between molecular-kinetic regime and hydrodynamic regime occurs is thoroughly estimated since the theories do not allow the exact calculation of this value. Here for the first time, an empirical power law exponent (n=0.08+/-0.05) is proposed for

  8. Self-Assembly in Aqueous Oppositely Charged Gemini Surfactants: A Correlation between Morphology and Solubilization Efficacy.

    Science.gov (United States)

    Singh, Sneha; Bhadoria, Arti; Parikh, Kushan; Yadav, Sanjay Kumar; Kumar, Sugam; Aswal, V K; Kumar, Sanjeev

    2017-09-21

    Micellization behavior of oppositely charged gemini surfactants (anionic surfactant; phosphoric acid, P,P'-1,4-butanedieyl, P,P'-didodecylester, disodium salt (12-4-12A), and cationic surfactant; butanediyl-1,4, bis (N,N-hexadecyl ammonium) dibromide (16-4-16) or (D-isosorbate-1,4-diyl bis(N,N-dimethyl-N-hexadecylammonium acetoxy) dichloride (16-Isb-16)) has been studied (individually or of a gemini mixture) by conductivity and surface tension measurements. Critical micelle concentration (CMC) data show both synergistic (for 12-4-12A + 16-Isb-16) and antagonistic (for 12-4-12A + 16-4-16) interactions between the two components. Small angle neutron scattering (SANS) measurement shows formation of various aggregates, spherical (or ellipsoidal), rod-shaped, and vesicular, by changing the mole fraction (at fixed total surfactant concentration, 10 mM). Viscosity, zeta (ζ)-potential, and transmission electron microscopy (TEM) data are found in conformity of SANS results. Surprisingly, two morphologies (vesicles and rod-shaped micelles) show stability in a wide temperature range (303-343 K). The behavior has been explained on the basis of temperature induced dehydration and depletion of micellar charge. Aqueous gemini mixtures, of different morphologies, have been used for the determination of solubilization efficacy (using UV-visible spectrophotometer) toward polycyclic aromatic hydrocarbons (PAHs: anthracene; pyrene or fluorene). Molar solubilization ratio (MSR) data suggest that vesicles enhance the solubilization efficacy. SANS analysis shows that vesicle bilayer thickness increases upon PAH solubilization. The order of bilayer thickness increase is found to be anthracene > pyrene > fluorene, which is in the same order as the aqueous solubility of PAHs. This is the first report which correlates morphology to the solubilization efficacy.

  9. Measuring air-water interfacial area for soils using the mass balance surfactant-tracer method.

    Science.gov (United States)

    Araujo, Juliana B; Mainhagu, Jon; Brusseau, Mark L

    2015-09-01

    There are several methods for conducting interfacial partitioning tracer tests to measure air-water interfacial area in porous media. One such approach is the mass balance surfactant tracer method. An advantage of the mass-balance method compared to other tracer-based methods is that a single test can produce multiple interfacial area measurements over a wide range of water saturations. The mass-balance method has been used to date only for glass beads or treated quartz sand. The purpose of this research is to investigate the effectiveness and implementability of the mass-balance method for application to more complex porous media. The results indicate that interfacial areas measured with the mass-balance method are consistent with values obtained with the miscible-displacement method. This includes results for a soil, for which solid-phase adsorption was a significant component of total tracer retention. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Transport and Development of Microemulsionand Surfactant Stabilized Iron Nanoparticles for In Situ Remediation

    Science.gov (United States)

    Hsu, Dennis

    This work describes the mobility assessments of microemulsion-stabilized iron oxide nanoparticles and anionic surfactant sodium diethyl hexyl phosphate (SDEHP)-stabilized nanoscale zero valent iron (NZVI) particles in laboratory porous media. The two formulations tested in this work achieved stable iron nanoparticle suspensions for months and prepared via a simple "one-pot" synthesis method developed by Wang et al. Both formulations were tested under field scale velocity of 5 m/day with no mechanical aid during the injection. A three-compartment model, involving colloid diffusion theory, diffusion theory and tailing was applied to describe the breakthrough curves of the studies. The obtained breakthrough curves of both formulations implied excellent transport in porous media with steady plateau C/Co at 0.8-0.9 and recovery of up to 0.95 for SDEHP stabilized NZVI. Post analysis on the retention of iron on the porous media implied ideal transport with consistent data to the breakthrough curves.

  11. Surfactant-enhanced control of track-etch pore morphology

    International Nuclear Information System (INIS)

    Apel', P.Yu.; Blonskaya, I.V.; Didyk, A.Yu.; Dmitriev, S.N.; Orelovich, O.L.; Samojlova, L.I.; Vutsadakis, V.A.; Root, D.

    2000-01-01

    The influence of surfactants on the process of chemical development of ion tracks in polymers is studied. Based on the experimental data, a mechanism of the surfactant effect on the track-etch pore morphology is proposed. In the beginning of etching the surfactant is adsorbed on the surface and creates a layer that is quasi-solid and partially protects the surface from the etching agent. However, some etchant molecules diffuse through the barrier and react with the polymer surface. This results in the formation of a small hole at the entrance to the ion track. After the hole has attained a few annometers in diameter, the surfactant molecules penetrate into the track and cover its walls. Further diffusion of the surfactant into the growing pore is hindered. The adsorbed surfactant layer is not permeable for large molecules. In contrast, small alkali molecules and water molecules diffuse into the track and provide the etching process enlarging the pore. At this stage the transport of the surfactant into the pore channel can proceed only due to the lateral diffusion in the adsorbed layer. The volume inside the pore is free of surfactant molecules and grows at a higher rate than pore entrance. After a more prolonged etching the bottle-like (or 'cigar-like') pore channels are formed. The bottle-like shape of the pore channels depends on the etching conditions such as alkali and surfactant concentration, temperature, and type of the surfactant. The use of surfactants enables one to produce track-etch membranes with improved flow rate characteristics compared with those having cylindrical pores with the same nominal pore diameters

  12. Identifying the Imprint of Surfactant Stabilisation in Whitecap Foam Evolution

    Science.gov (United States)

    Callaghan, A. H.; Deane, G. B.; Stokes, D.

    2016-02-01

    Surfactants are ubiquitous in the world's oceans and can affect climatically-relevant processes such as air-sea gas exchange, sea spray aerosol (SSA) flux, and air-sea momentum transfer. Surfactants are amphiphilic and help form the physically and chemically distinct ocean surface microlayer (SML), however, the spatial distribution, concentration and composition of the SML is not well understood, especially under conditions of vigorous wave breaking. Like the SML, breaking waves also influence physical exchange processes at the air-sea interface, and oceanic whitecap foam coverage is commonly used to quantify bubble-mediated exchange processes. However, surfactants can increase the lifetime of foam over clean water conditions, potentially complicating the use of whitecap coverage to parameterise air-sea gas exchange and SSA production flux. A better understanding of how surfactants affect the evolution of whitecap foam is needed to improve whitecap parameterisations of bubble-mediated processes, and may also provide a remote sensing approach to map the spatial distribution of surfactants at the water surface. Here we present results from a laboratory study that looked at whitecap foam evolution in "clean" and "surfactant-added" seawater regimes. We find that the whitecap foam area growth timescale is largely insensitive to the presence of surfactants, but that surfactant stabilization of whitecap foam becomes important during the whitecap foam area decay phase. The timescale at which this occurs appears to be consistent for breaking waves of different scale and intensity. A simple method is then used to isolate the surfactant signal and derive an equivalent "clean" seawater foam decay time for the whitecaps in the "surfactant-added" regime. The method is applied to oceanic whitecaps and results compared to the laboratory whitecaps from the "clean" and "surfactant-added" regimes.

  13. Surfactant-bound monolithic columns for separation of proteins in capillary high performance liquid chromatography.

    Science.gov (United States)

    Gu, Congying; He, Jun; Jia, Jinping; Fang, Nenghu; Simmons, Robert; Shamsi, Shahab A

    2010-01-22

    A surfactant-bound monolithic stationary phase based on the co-polymerization of 11-acrylamino-undecanoic acid (AAUA) is designed for capillary high performance liquid chromatography (HPLC). Using D-optimal design, the effect of the polymerization mixture (concentrations of monomer, crosslinker and porogens) on the chromatographic performance (resolution and analysis time) of the AAUA-EDMA monolithic column was evaluated. The polymerization mixture was optimized using three proteins as model test solutes. The D-optimal design indicates a strong dependence of chromatographic parameters on the concentration of porogens (1,4-butanediol and water) in the polymerization mixture. Optimized solutions for fast separation and high resolution separation, respectively, were obtained using the proposed multivariate optimization. Differences less than 6.8% between the predicted and the experimental values in terms of resolution and retention time indeed confirmed that the proposed approach is practical. Using the optimized column, fast separation of proteins could be obtained in 2.5 min, and a tryptic digest of myoglobin was successfully separated on the high resolution column. The physical properties (i.e., morphology, porosity and permeability) of the optimized monolithic column were thoroughly investigated. It appears that this surfactant-bound monolith may have a great potential as a new generation of capillary HPLC stationary phase. Copyright 2009 Elsevier B.V. All rights reserved.

  14. Surfactant-Bound Monolithic Columns for Separation of Proteins in Capillary High Performance Liquid Chromatography

    Science.gov (United States)

    Gu, Congying; He, Jun; Jia, Jinping; Fang, Nenghu; Simmons, Robert; Shamsi, Shahab A.

    2011-01-01

    A surfactant bound monolithic stationary phase based on the co-polymerization of 11-acrylamino-undecanoic acid (AAUA) is designed for capillary high performance liquid chromatography (HPLC). Using D-optimal design, the effect of the polymerization mixture (concentrations of monomer, crosslinker and porogens) on the chromatographic performance (resolution and analysis time) of the AAUA-EDMA monolithic column was evaluated. The polymerization mixture was optimized using three proteins as model test solutes. The D-optimal design indicates a strong dependence of chromatographic parameters on the concentration of porogens (1,4-butanediol and water) in the polymerization mixture. Optimized solutions for fast separation and high resolution separation, respectively, were obtained using the proposed multivariate optimization. Differences less than 6.8% between the predicted and the experimental values in terms of resolution and retention time indeed confirmed that the proposed approach is practical. Using the optimized column, fast separation of proteins could be obtained in 2.5 min, and a tryptic digest of myoglobin was successfully separated on the high resolution column. The physical properties (i.e. morphology, porosity and permeability) of the optimized monolithic column were thoroughly investigated. It appears that this surfactant-bound monolith may have a great potential as a new generation of capillary HPLC stationary phase. PMID:20031139

  15. COMPUTER SIMULATIONS OF SPRAY RETENTION BY A 3D BARLEY PLANT: EFFECT OF FORMULATION SURFACE TENSION.

    Science.gov (United States)

    Massinon, M; De Cock, N; Salah, S Ouled Taleb; Lebeau, F

    2015-01-01

    A spray retention model was used in this study to explore theoretically the effect of a range of mixture surface tension on the spray retention and the variability of deposits. The spray retention model was based on an algorithm that tested whether droplets from a virtual nozzle intercepted a 3D plant model. If so, the algorithm determined the contribution of the droplet to the overall retention depending on the droplet impact behaviour on the leaf; adhesion, rebound or splashing. The impact outcome probabilities, function of droplet impact energy, were measured using high-speed imaging on an excised indoor grown barley leaf (BBCH12) both for pure water (surface tension of 0.072 N/m) and a non-ionic super spreader (static surface tension of 0.021 N/m) depending on the surface orientation. The modification of spray mixture properties in the simulations was performed by gradually changing the spray the droplet impact probabilities between pure water and a solution with non-ionic surfactant exhibiting super spreading properties. The plant architecture was measured using a structured light scanner. The final retention was expressed as the volume of liquid retained by the whole plant relative to the projected leaf surface area in the main spray direction. One hundred simulations were performed at different volumes per hectare and flat-fan nozzles for each formulation surface tension. The coefficient of variation was used as indicator of variability of deposits. The model was able to discriminate between mixture surface tension. The spray retention increased as the mixture surface tension decreased. The variability of deposits also decreased as the surface tension decreased. The proposed modelling approach provides a suited tool for sensitivity analysis: nozzle kind, pressure, volume per hectare applied, spray mixture physicochemical properties, plant species, growth stage could be screened to determine the best spraying characteristics maximizing the retention. The

  16. MOLECULAR-DYNAMICS SIMULATIONS OF CARBOHYDRATE-BASED SURFACTANTS IN SURFACTANT WATER OIL SYSTEMS

    NARCIS (Netherlands)

    VANBUUREN, AR; BERENDSEN, HJC

    Molecular dynamics simulations of two monolayers of carbohydrate-based surfactants (decyl alpha-glucoside and decyl beta-glucoside) at the interface between liquid decane and liquid water have been performed with the purpose to study the properties of these monolayers on a molecular and atomic

  17. RELATION BETWEEN SURFACTANT STRUCTURE AND PROPERTIES OF SPHERICAL MICELLES - 1-ALKYL-4-ALKYLPYRIDINIUM HALIDE SURFACTANTS

    NARCIS (Netherlands)

    NUSSELDER, JJH; ENGBERTS, JBFN

    1991-01-01

    This paper describes a detailed study of the properties of spherical micelles formed from 18 1-alkyl-4-alkylpyridinium iodides. Structural variations in the surfactants include (i) branching of the 4-alkyl chain while keeping the number of carbons in the chain invariant and (ii) variation of the

  18. Design of Surfactant Protein B Peptide Mimics Based on the Saposin Fold for Synthetic Lung Surfactants.

    Science.gov (United States)

    Walther, Frans J; Gordon, Larry M; Waring, Alan J

    2016-01-01

    Surfactant protein (SP)-B is a 79-residue polypeptide crucial for the biophysical and physiological function of endogenous lung surfactant. SP-B is a member of the Saposin or Saposin-like proteins (SAPLIP) family of proteins that share an overall three-dimensional folding pattern based on secondary structures and disulfide connectivity and exhibit a wide diversity of biological functions. Here we review the synthesis, molecular biophysics and activity of synthetic analogs of Saposin proteins designed to mimic those interactions of the parent proteins with lipids that enhance interfacial activity. Saposin proteins generally interact with target lipids as either monomers or multimers via well-defined amphipathic helices, flexible hinge domains, and insertion sequences. Based on the known 3D-structural motif for the Saposin family, we show how bioengineering techniques may be used to develop minimal peptide constructs that maintain desirable structural properties and activities in biomedical applications. One important application is the molecular design, synthesis and activity of Saposin mimics based on the SP-B structure. Synthetic lung surfactants containing active SP-B analogs may be potentially useful in treating diseases of surfactant deficiency or dysfunction including the neonatal respiratory distress syndrome and acute lung injury/acute respiratory distress syndrome.

  19. Neonatal varicella pneumonia, surfactant replacement therapy

    Directory of Open Access Journals (Sweden)

    Mousa Ahmadpour-kacho

    2015-12-01

    Full Text Available Background: Chickenpox is a very contagious viral disease that caused by varicella-zoster virus, which appears in the first week of life secondary to transplacental transmission of infection from the affected mother. When mother catches the disease five days before and up to two days after the delivery, the chance of varicella in neonate in first week of life is 17%. A generalized papulovesicular lesion is the most common clinical feature. Respiratory involvement may lead to giant cell pneumonia and respiratory failure. The mortality rate is up to 30% in the case of no treatment, often due to pneumonia. Treatment includes hospitalization, isolation and administration of intravenous acyclovir. The aim of this case report is to introduce the exogenous surfactant replacement therapy after intubation and mechanical ventilation for respiratory failure in neonatal chickenpox pneumonia and respiratory distress. Case Presentation: A seven-day-old neonate boy was admitted to the Neonatal Intensive Care Unit at Amirkola Children’s Hospital, Babol, north of Iran, with generalized papulovesicular lesions and respiratory distress. His mother has had a history of Varicella 4 days before delivery. He was isolated and given supportive care, intravenous acyclovir and antibiotics. On the second day, he was intubated and connected to mechanical ventilator due to severe pneumonia and respiratory failure. Because of sever pulmonary involvement evidenced by Chest X-Ray and high ventilators set-up requirement, intratracheal surfactant was administered in two doses separated by 12 hours. He was discharged after 14 days without any complication with good general condition. Conclusion: Exogenous surfactant replacement therapy can be useful as an adjunctive therapy for the treatment of respiratory failure due to neonatal chickenpox.

  20. Surfactant-like properties of extractants molecules

    International Nuclear Information System (INIS)

    Bauduin, Pierre; Bauer, Caroline; Bance, Amelie; Gassin, Gaelle; Diat, Olivier; Zemb, Thomas

    2012-01-01

    Solvent extraction is based on aqueous phase/oil/extractant systems with the extractant being exclusively soluble in oil and which perform the extraction of ions (or salts) from the aqueous phase. The present contribution aims at investigating solvent extraction systems using a classical approach in surfactant science. The discussion is based on the description of the phase diagrams topology and on molecular geometrical considerations. A thermodynamic model was developed by considering the packing constraints of extractant molecules in the film forming extractant reverse micelles present in oil. It enabled the prediction of water solubility in the reverse micelles as well as the size of the micelles obtained experimentally. (authors)

  1. Surfactant protein D is proatherogenic in mice

    DEFF Research Database (Denmark)

    Sørensen, Grith Lykke; Madsen, Jens; Kejling, Karin

    2006-01-01

    Surfactant protein D (SP-D) is an important innate immune defense molecule that mediates clearance of pathogens and modulates the inflammatory response. Moreover, SP-D is involved in lipid homeostasis, and pulmonary accumulation of phospholipids has previously been observed in SP-D-deficient (Spd......-alpha was reduced in Spd-/- mice (45% difference). SP-D was proatherogenic in the mouse model used. The effect is likely to be due to the observed disturbances of plasma lipid metabolism and alteration of the inflammatory process, which underlie the reduced susceptibility to atherosclerosis in Spd-/- mice....

  2. Size separation of analytes using monomeric surfactants

    Science.gov (United States)

    Yeung, Edward S.; Wei, Wei

    2005-04-12

    A sieving medium for use in the separation of analytes in a sample containing at least one such analyte comprises a monomeric non-ionic surfactant of the of the general formula, B-A, wherein A is a hydrophilic moiety and B is a hydrophobic moiety, present in a solvent at a concentration forming a self-assembled micelle configuration under selected conditions and having an aggregation number providing an equivalent weight capable of effecting the size separation of the sample solution so as to resolve a target analyte(s) in a solution containing the same, the size separation taking place in a chromatography or electrophoresis separation system.

  3. Exploring the affinity binding of alkylmaltoside surfactants to bovine serum albumin and their effect on the protein stability: A spectroscopic approach.

    Science.gov (United States)

    Hierrezuelo, J M; Carnero Ruiz, C

    2015-08-01

    Steady-state and time-resolved fluorescence together with circular dichroism (CD) spectroscopic studies was performed to examine the interactions between bovine serum albumin (BSA) and two alkylmaltoside surfactants, i.e. n-decyl-β-D-maltoside (β-C10G2) and n-dodecyl-β-D-maltoside (β-C12G2), having identical structures but different tail lengths. Changes in the intrinsic fluorescence of BSA from static as well as dynamic measurements revealed a weak protein-surfactant interaction and gave the corresponding binding curves, suggesting that the binding mechanism of surfactants to protein is essentially cooperative in nature. The behavior of both surfactants is similar, so that the differences detected were attributed to the more hydrophobic nature of β-C12G2, which favors the adsorption of micelle-like aggregates onto the protein surface. These observations were substantially demonstrated by data derived from synchronous, three-dimensional and anisotropy fluorescence experiments. Changes in the secondary structure of the protein induced by the interaction with surfactants were analyzed by CD to determine the contents of α-helix and β-strand. It was noted that whereas the addition of β-C10G2 appears to stabilize the secondary structure of the protein, β-C12G2 causes a marginal denaturation of BSA for a protein:surfactant molar ratio as high as 1 to 100. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Surfactant softening of plant leaf cuticle model wax--a Differential Scanning Calorimetry (DSC) and Quartz Crystal Microbalance with Dissipation (QCM-D) study.

    Science.gov (United States)

    Fagerström, Anton; Kocherbitov, Vitaly; Westbye, Peter; Bergström, Karin; Arnebrant, Thomas; Engblom, Johan

    2014-07-15

    The aim was to quantify the softening effect that two surfactants (C10EO7 and C8G1.6) have on a plant leaf cuticle model wax. Effects on the thermotropic phase behavior and fluidity of the wax (C22H45OH/C32H66/H2O) were determined. The model wax is crystalline at ambient conditions, yet it is clearly softened by the surfactants. Both surfactants decreased the transition temperatures in the wax and the G″/G' ratio of the wax film increased in irreversible steps following surfactant exposure. C10EO7 has a stronger fluidizing effect than C8G1.6 due to stronger interaction with the hydrophobic waxes. Intracuticular waxes (IW) comprise both crystalline and amorphous domains and it has previously been proposed that the fluidizing effects of surfactants are due to interactions with the amorphous parts. New data suggests that this may be a simplification. Surfactants may also absorb in crevices between crystalline domains. This causes an irreversible effect and a softer cuticle wax. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. A liquid CO2-compatible hydrocarbon surfactant: experiment and modelling

    NARCIS (Netherlands)

    Banerjee, S.; Kleijn, J.M.; Cohen Stuart, M.A.; Leermakers, F.A.M.

    2013-01-01

    Surfactants soluble in liquid CO2 are rare and knowledge on interfacial and self-assembly behaviour is fragmented. We found that polyoxyethylene (5) isooctylphenyl ether is interfacially active at the water–liquid CO2 interface. Water–liquid CO2 interfacial tension was measured at various surfactant

  6. Binding of alkylpyridinium chloride surfactants to sodium polystyrene sulfonate

    NARCIS (Netherlands)

    Ishiguro, M.; Koopal, L.K.

    2009-01-01

    Binding of cationic surfactants to anionic polymers is well studied. However, the surfactant binding characteristics at very low concentration near the start of binding and at high concentration, where charge compensation may Occur. are less well known. Therefore, the binding characteristics of

  7. New mechanisms for phase separation in polymer-surfactant mixtures

    NARCIS (Netherlands)

    Currie, E.P.K.; Cohen Stuart, M.A.; Borisov, O.V.

    2000-01-01

    The cooperative association of ionic surfactants with polymer chains leads to quite novel features in the phase behaviour of polymer solutions. Using an analytic mean-field model, we analyze phase equilibria in solutions of neutral polymers mixed with ionic surfactants. We predict the possibilities

  8. Perfluoroalkyl Epoxides: Synthesis and Conversion into Ionic Surfactants

    Directory of Open Access Journals (Sweden)

    Abdelhamid Ayari

    2014-07-01

    Full Text Available Perfluoroalkylated surfactants having a quaternary ammonium surrounded by three hydroxyl groups as hydrophilic moiety and a perfluoroalkyl chain as tail were obtained by coupling diethanolamine with perfluoroalkylated epoxide followed by quaternisation. The amphiphilic properties of these surfactants were investigated by measuring their surface and interfacial tensions.

  9. Influence of salts on dynamics properties of drag reducing surfactants

    Czech Academy of Sciences Publication Activity Database

    Myška, Jiří; Lin, Z.; Štěpánek, Petr; Zakin, J. L.

    2001-01-01

    Roč. 97, 2/3 (2001), s. 251-266 ISSN 0377-0257 R&D Projects: GA AV ČR IAA2060804; GA ČR GA101/99/1431 Keywords : influence of salts * zwitterionic surfactants * cationic surfactants Subject RIV: BK - Fluid Dynamics Impact factor: 1.347, year: 2001

  10. Effects of surfactants on size and structure of amylose nanoparticles ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... The present work investigated the influence of surfactants on size and structure of amylose nanoparticles (ANPs) prepared through precipitation. ANPs were fabricated using absolute ethanol containing surfactants (Tween80, Span80 and mixtures of Tween80 and Span80 with ratios of 25/75, 50/50 and ...

  11. Effect of Surfactants on Plasmid DNA Stability and Release from ...

    African Journals Online (AJOL)

    Purpose: To evaluate the effect of surfactants on plasmid DNA during preparation and release from polylactic glycolide (PLGA) microspheres. Methods: Various surfactants, both ionic and non-ionic (Span, Tween, Triton X100, cetyltrimethylammonium bromide and sodium dodecyl sulphate), were added during the ...

  12. Photoisomerization of merocyanine 540 in polymer-surfactant ...

    Indian Academy of Sciences (India)

    Photoisomerization of merocyanine 540 (MC540) in a polymer-surfactant aggregate is studied using picosecond time resolved emission spectroscopy. The aggregate consists of the polymer, poly(vinylpyrrolidone) (PVP) and the surfactant, sodium dodecyl sulphate (SDS). With increase in the concentration of SDS in an ...

  13. The cost and effectiveness of surfactant replacement therapy at ...

    African Journals Online (AJOL)

    Objective. To assess the impact of surfactant replacement therapy (SRl) on the outcome of hyaline membrane disease (HMD) and to assess the cost implications of a policy of selective administration of artificial surfactant. Design. The short-term outcome of 103 newborns ventilated for HMD (61 selected for SRT according to ...

  14. Polyfluorinated alkyl phosphate ester surfactants - current knowledge and knowledge gaps

    DEFF Research Database (Denmark)

    Taxvig, Camilla; Rosenmai, Anna Kjerstine; Vinggaard, Anne Marie

    2014-01-01

    information on fluorochemicals. Polyfluorinated alkyl phosphate ester surfactants (PAPs) belong to the group of polyfluorinated alkyl surfactants. They have been detected in indoor dust and are widely used in food-contact materials, from which they have the ability to migrate into food. Toxicological data...

  15. Small-angle neutron scattering studies of nonionic surfactant: Effect

    Indian Academy of Sciences (India)

    Micellar solution of nonionic surfactant -dodecyloligo ethyleneoxide surfactant, decaoxyethylene monododecyl ether [CH3(CH2)11(OCH2CH2)10OH], C12E10 in D2O solution have been analysed by small-angle neutron scattering (SANS) at different temperatures (30, 45 and 60°C) both in the presence and absence of ...

  16. Adsorption and intercalation of anionic surfactants onto layered ...

    Indian Academy of Sciences (India)

    Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas the sulfate ...

  17. Polymeric surfactants for enhanced oil recovery : A review

    NARCIS (Netherlands)

    Raffa, Patrizio; Broekhuis, Antonius A.; Picchioni, Francesco

    Chemical enhanced oil recovery (EOR) is surely a topic of interest, as conventional oil resources become more scarce and the necessity of exploiting heavy and unconventional oils increases. EOR methods based on polymer flooding, surfactant-polymer flooding and alkali-surfactant-polymer flooding are

  18. Adsorption and intercalation of anionic surfactants onto layered ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas.

  19. Surfactants assist in lipid extraction from wet Nannochloropsis sp.

    Science.gov (United States)

    Wu, Chongchong; Xiao, Ye; Lin, Weiguo; Zhu, Junying; De la Hoz Siegler, Hector; Zong, Mingsheng; Rong, Junfeng

    2017-11-01

    An efficient approach involving surfactant treatment, or the modification and utilization of surfactants that naturally occur in algae (algal-based surfactants), was developed to assist in the extraction of lipids from wet algae. Surfactants were found to be able to completely replace polar organic solvents in the extraction process. The highest yield of algal lipids extracted by hexane and algal-based surfactants was 78.8%, followed by 78.2% for hexane and oligomeric surfactant extraction, whereas the lipid yield extracted by hexane and ethanol was only 60.5%. In addition, the saponifiable lipids extracted by exploiting algal-based surfactants and hexane, or adding oligomeric surfactant and hexane, accounted for 78.6% and 75.4% of total algal lipids, respectively, which was more than 10% higher than the lipids extracted by hexane and ethanol. This work presents a method to extract lipids from algae using only nonpolar organic solvents, while obtaining high lipid yields and high selectivity to saponifiables. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Surfactant-assisted liquefaction of particulate carbonaceous substances

    Science.gov (United States)

    Hsu, G. C. (Inventor)

    1978-01-01

    A slurry of carbonaceous particles such as coal containing an oil soluble polar substituted oleophilic surfactant, suitably an amine substituted long chain hydrocarbon, is liquefied at high temperature and high hydrogen presence. The pressure of surfactant results in an increase in yield and the conversion product contains a higher proportion of light and heavy oils and less asphaltene than products from other liquefaction processes.

  1. Colloidal stability influenced by inhomogeneous surfactant assemblies in confined spaces

    NARCIS (Netherlands)

    Jodar-Reyes, A.B.; Leermakers, F.A.M.

    2009-01-01

    Recently, a molecular-level self-consistent field approach was used to show that some surfactants assemblies (with local cylindrical structure) can bridge between two surfaces that in turn are covered by surfactant bilayers. The stability of such a connection is related to a higher end-cap (free)

  2. Surfactant Proteins in Smoking-Related Lung Disease.

    Science.gov (United States)

    Papaioannou, Andriana I; Papiris, Spyridon; Papadaki, Georgia; Manali, Effrosyni D; Roussou, Aneza; Spathis, Aris; Karakitsos, Petros; Kostikas, Konstantinos

    2016-01-01

    Pulmonary surfactant is a highly surface-active mixture of proteins and lipids that is synthesized and secreted in the alveoli by type II epithelial cells and is found in the fluid lining the alveolar surface. The protein part of surfactant constitutes two hydrophilic proteins (SP-A and SP-D) that regulate surfactant metabolism and have immunologic functions, and two hydrophobic proteins (SP-B and SP-C), which play a direct role in the organization of the surfactant structure in the interphase and in the stabilization of the lipid layers during the respiratory cycle. Several studies have shown that cigarette smoke seems to affect, in several ways, both surfactant homeostasis and function. The alterations in surfactants' biophysical properties caused by cigarette smoking, contribute to the development of several smoking related lung diseases. In this review we provide information on biochemical and physiological aspects of the pulmonary surfactant and on its possible association with the development of two major chronic diseases of the lung known to be related to smoking, i.e. chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Additional information on the possible role of surfactant protein alterations and/or dysfunction in the combination of these two conditions, recently described as combined pulmonary fibrosis and emphysema (CPFE) are also provided.

  3. Method of separating a surfactant from a liquid

    NARCIS (Netherlands)

    Van den Berg, A.W.; Lems, S.

    2002-01-01

    The present invention relates to a method of separating a surfactant from a liquid, such as a wastewater stream from an industrial laundry. In accordance with the invention, the liquid is cooled to below the Krafft temperature of the surfactant and subjected to centrifugal forces for the separation

  4. The Role of Some Retention Aids in Water Based Gravure Printing

    International Nuclear Information System (INIS)

    El-Sherbiny, S.; Morsy, F.A.; Abdel- Sayed, E.S.

    2005-01-01

    Several commercial retention systems employing either synthetic or natural additives are now able to achieve an acceptable level of filler retention even during high speed paper forming. However, despite their importance, there have been very few reports in the literature regarding the influence of different retention aids on gravure water based ink printability. In the current work, a series of uncoated hand sheets containing the retention aids rosin aids rosin-alum, cationic starch, polyacrylamide and chitosan were prepared under controlled ph conditions. Chitosan is a natural additive only very recently employed in commercial papermaking systems. After printing with two water based ink systems, both printability and print quality were then assessed in terms of print density, gloss and ink transfer. The effect of surfactant addition to gravure water based ink was also studied. The results showed that the amount of ink transferred and the print density both decreased as the percentage of the selected additives increased. The addition of chitosan to the paper furnish led to a substantial decrease in both the amount of ink transferred and the print density compared to the other additives. Conversely, the presence of surfactant in the printing ink enhanced the print density and also increased the amount of ink transferred. In addition, results obtained demonstrated that printing with water based ink greatly decreased the print gloss in comparison to the paper gloss. Increasing the addition level of the selected additives led to an increase of print gloss due to a decrease in the amount of ink transferred. Increasing the ph of the pulp suspension containing 1 % of the selected additives increased the print density in all cases, except when using cationic starch

  5. Forecasting Mobile Games' Retention using Weka

    Directory of Open Access Journals (Sweden)

    Roxana Ioana STIRCU

    2016-08-01

    Full Text Available In the actual market, when thousands of mobile, PC or console games are released every year, developing and publishing a successful and profitable game is a very challenging process. The gaming industry is very competitive, and all the distribution channels are full of projects competing for players. More and more companies are investing a lot of time and resources in developing an effective way to save and store all the data used and generated by their game's users. In order to develop effective and successful projects, companies adopted a lot of tools and techniques from other domains, like Statistics, Business Intelligence, or Project Management. The method most currently used is Analytics, defined as the process of discovering and communicating patterns in data, to better understand players' behavior, analyze their in-game interaction, and predicting their next in-game actions. This represents a huge step forward for the gaming industry, towards successful projects and user-tailored gaming experience. In this article the problem of users' retention is discussed, and a regression model is proposed in order to forecast players' retention, and prevent players from leaving the game.

  6. Delivery and performance of surfactant replacement therapies to treat pulmonary disorders

    Science.gov (United States)

    El-Gendy, Nashwa; Kaviratna, Anubhav; Berkland, Cory; Dhar, Prajnaparamita

    2013-01-01

    Lung surfactant is crucial for optimal pulmonary function throughout life. An absence or deficiency of surfactant can affect the surfactant pool leading to respiratory distress. Even if the coupling between surfactant dysfunction and the underlying disease is not always well understood, using exogenous surfactants as replacement is usually a standard therapeutic option in respiratory distress. Exogenous surfactants have been extensively studied in animal models and clinical trials. The present article provides an update on the evolution of surfactant therapy, types of surfactant treatment, and development of newer-generation surfactants. The differences in the performance between various surfactants are highlighted and advanced research that has been conducted so far in developing the optimal delivery of surfactant is discussed. PMID:23919474

  7. Animal derived surfactant extract versus protein free synthetic surfactant for the prevention and treatment of respiratory distress syndrome.

    Science.gov (United States)

    Ardell, Stephanie; Pfister, Robert H; Soll, Roger

    2015-08-24

    A wide variety of surfactant preparations have been developed and tested including synthetic surfactants and surfactants derived from animal sources. Although clinical trials have demonstrated that both synthetic surfactant and animal derived surfactant preparations are effective, comparison in animal models has suggested that there may be greater efficacy of animal derived surfactant products, perhaps due to the protein content of animal derived surfactant. To compare the effect of animal derived surfactant to protein free synthetic surfactant preparations in preterm infants at risk for or having respiratory distress syndrome (RDS). Searches were updated of the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2014), PubMed, CINAHL and EMBASE (1975 through November 2014). All languages were included. Randomized controlled trials comparing administration of protein free synthetic surfactants to administration of animal derived surfactant extracts in preterm infants at risk for or having respiratory distress syndrome were considered for this review. Data collection and analysis were conducted according to the standards of the Cochrane Neonatal Review Group. Fifteen trials met the inclusion criteria. The meta-analysis showed that the use of animal derived surfactant rather than protein free synthetic surfactant resulted in a significant reduction in the risk of pneumothorax [typical relative risk (RR) 0.65, 95% CI 0.55 to 0.77; typical risk difference (RD) -0.04, 95% CI -0.06 to -0.02; number needed to treat to benefit (NNTB) 25; 11 studies, 5356 infants] and a marginal reduction in the risk of mortality (typical RR 0.89, 95% CI 0.79 to 0.99; typical RD -0.02, 95% CI -0.04 to -0.00; NNTB 50; 13 studies, 5413 infants).Animal derived surfactant was associated with an increase in the risk of necrotizing enterocolitis [typical RR 1.38, 95% CI 1.08 to 1.76; typical RD 0.02, 95% CI 0.01 to 0.04; number needed to treat to harm (NNTH) 50; 8

  8. Interaction between surfactant and titania in a detergent nanofluid system

    Science.gov (United States)

    Slamet, Redjeki, Athiek Sri

    2017-11-01

    Interaction between surfactant palm primary alkyl sulfonate (palm PAS) and tinania (TiO2) in nanofluid system have been studied. In this experiment, nanofluid is prepared as follow: a certain amount of titania is dispersing in a water as a host fluid, and then dissolving a certain amount of palm PAS into water and stirred followed with sonication. Characterisation of nanofluid is conducted by FTIR for chemical structure and UV Vis spectrofotometer for absorbance. The result shows a synergize interaction between surfactant and nanofluid. The presence of titania in surfactant solution will reduce the surfactantsurface tension from 32,7 mN/m to 31,5 mN/m and the presence of surfactant in nanofluid, will stabilize nanofluid system. The optimum ratio of titania : surfactant is 1 : 10 (w/w).

  9. Pulmonary Surfactants for Acute and Chronic Lung Diseases (Part II

    Directory of Open Access Journals (Sweden)

    O. A. Rozenberg

    2014-01-01

    Full Text Available Part 2 of the review considers the problem of surfactant therapy for acute respiratory distress syndrome (ARDS in adults and young and old children. It gives information on the results of surfactant therapy and prevention of ARDS in patients with severe concurrent trauma, inhalation injuries, complications due to complex expanded chest surgery, or severe pneumonias, including bilateral pneumonia in the presence of A/H1N1 influenza. There are data on the use of a surfactant in obstetric care and prevention of primary graft dysfunction during lung transplantation. The results of longterm use of surfactant therapy in Russia, suggesting that death rates from ARDS may be substantially reduced (to 20% are discussed. Examples of surfactant therapy for other noncritical lung diseases, such as permanent athelectasis, chronic obstructive pulmonary diseases, and asthma, as well tuberculosis, are also considered.

  10. NMR study of the dynamics of cationic gemini surfactant 14-2-14 in mixed solutions with conventional surfactants.

    Science.gov (United States)

    Jiang, Yan; Lu, Xing-Yu; Chen, Hong; Mao, Shi-Zhen; Liu, Mai-Li; Luo, Ping-Ya; Du, You-Ru

    2009-06-18

    Three kinds of conventional surfactants, namely, two nonionic surfactants [polyethylene glycol (23) lauryl ether (Brij-35) and Triton X-100 (TX-100)], one cationic surfactant [n-tetradecyltrimethyl ammonium bromide (TTAB)], and an anionic surfactant [sodium n-dodecyl sulfate (SDS)}, were mixed into the quaternary ammonium gemini surfactant [C(14)H(29)N(+)(CH(3))(2)](2)(CH(2))(2).2Br(-) (14-2-14) in aqueous solution. The exchange rate constants between 14-2-14 molecules in the mixed micelles and those in the bulk solution were detected using two nuclear magnetic resonance (NMR) methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). The results obtained from these two methods were consistent. Both showed that mixing a nonionic conventional surfactant, either Brij-35 or TX-100, enhanced the exchange process between the 14-2-14 molecules in the mixed micelles and those in the bulk solution. In contrast, the anionic surfactant SDS and the cationic surfactant TTAB slowed the process slightly.

  11. A multicenter, randomized trial comparing synthetic surfactant with modified bovine surfactant extract in the treatment of neonatal respiratory distress syndrome

    NARCIS (Netherlands)

    Adams, E; Vollman, J; Giebner, D; Maurer, M; Dreyer, G; Bailey, L; Anderson, M; Mefford, L; Beaumont, E; Sutton, D; Puppala, B; Mangurten, HH; Secrest, J; Lewis, WJ; Carteaux, P; Bednarek, F; Welsberger, S; Gosselin, R; Pantoja, AF; Belenky, A; Campbell, P; Patole, S; Duenas, M; Kelly, M; Alejo, W; Lewallen, P; DeanLieber, S; Hanft, M; Ferlauto, J; Newell, RW; Bagwell, J; Levine, D; Lipp, RW; Harkavy, K; Vasa, R; Birenbaum, H; Broderick, KA; Santos, AQ; Long, BA; Gulrajani, M; Stern, M; Hopgood, G; Hegyi, T; Alba, J; Christmas, L; McQueen, M; Nichols, N; Brown, M; Quissell, BJ; Rusk, C; Marks, K; Gifford, K; Hoehn, G; Pathak, A; Marino, B; Hunt, P; Fox, [No Value; Sharpstein, C; Feldman, B; Johnson, N; Beecham, J; Balcom, R; Helmuth, W; Boylan, D; Frakes, C; Magoon, M; Reese, K; Schwersenski, J; Schutzman, D; Soll, R; Horbar, JD; Leahy, K; Troyer, W; Juzwicki, C; Anderson, P; Dworsky, M; Reynolds, L; Urrutia, J; Gupta, U; Adray, C

    Objective. To compare the efficacy of a synthetic surfactant (Exosurf Neonatal, Burroughs-Wellcome Co) and a modified bovine surfactant extract (Survanta, Ross Laboratories) in the treatment of neonatal respiratory distress syndrome (RDS). Design. Multicenter, randomized trial. Setting. Thirty-eight

  12. Investigations into surfactant/gas hydrate relationship

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Rudy; Zhang, Guochang; Dearman, Jennifer; Woods, Charles [Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762 (United States)

    2007-03-15

    Gas hydrates have unique physical properties portending useful industrial applications of gas storage, gas separation, or water desalination. When gas hydrates were found in the early 1990s to occur naturally and abundantly in seafloors, three other primary interests and concerns emerged: potential new energy source, climate threat from their greenhouse gases, and seafloor instabilities. This paper presents research showing how anionic synthetic surfactants helped develop an industrial gas hydrate storage process for natural gas and how naturally-occurring in-situ anionic biosurfactants influence the formation and placement of gas hydrates in ocean sediments. The catalytic effects, mechanisms, and surface specificities imparted by synthetic surfactants in the gas storage process and imparted by biosurfactants in porous media are discussed. The Bacillus subtilis bacterium that is indigenous to gas hydrate mounds in the Gulf of Mexico was cultured in the laboratory. Its biosurfactant was separated and found to catalyze gas hydrates in porous media. The experiments indicate that seafloor-biosurfactants can be produced rapidly in-situ to achieve threshold concentrations whereby hydrates are promoted. The biosurfactants accumulate and promote hydrate formation on specific mineral surfaces such as sodium montmorillonite. (author)

  13. Surfactant secretion and clearance in the newborn

    International Nuclear Information System (INIS)

    Stevens, P.A.; Wright, J.R.; Clements, J.A.

    1989-01-01

    Pregnant rabbits (30 days) were injected intravenously with [3H]choline 8 h before delivery. The fetuses were delivered, and lung lavage and lamellar body phospholipids (PL) were analyzed. Some newborns also received radioactively labeled surfactant intratracheally on delivery and were permitted to breathe. With time, intratracheal label decreased in lavage and appeared in the lamellar body fraction, and intravenous label accumulated in both pools. Using a tracer analysis for non-steady state, we calculated surfactant secretion and clearance rates for the newborn period. Before birth, both rates rose slightly from 1.8 micrograms PL.g body wt-1.h-1 at 6 h before birth to 7.3 at birth. Immediately after birth, secretion rate rose to 37.7 micrograms PL.g body wt-1.h-1. Between 1.5 and 2 h after birth it fell to a minimum of 1.8 micrograms PL.g body wt-1.h-1 and then rose slowly to 6.0 at 12 h. After birth, clearance rate increased less than secretion rate (maximum 24.7 micrograms PL.g body wt-1.h-1 shortly after birth) then followed the same pattern but did not balance secretion rate in the 1st day

  14. Reversal of multidrug resistance by surfactants.

    Science.gov (United States)

    Woodcock, D. M.; Linsenmeyer, M. E.; Chojnowski, G.; Kriegler, A. B.; Nink, V.; Webster, L. K.; Sawyer, W. H.

    1992-01-01

    Cremophor EL, a pharmacologically inactive solubilising agent, has been shown to reverse multidrug resistance (MDR). Using flow cytometric evaluation of equilibrium intracellular levels of daunorubicin (DNR), we found that eight other surface active agents will also reverse MDR. All the active detergents contain polyethoxylated moieties but have no similarities in their hydrophobic components. The properties of three polyethoxylated surfactants that showed the lowest toxicities, Cremophor, Tween 80 and Solutol HS15, were examined in more detail. The concentrations of Tween 80 and Solutol required to reverse DNR exclusion were 10-fold lower than for Cremophor. However while concentrations greater than or equal to 1:10(2) of the former two surfactants resulted in breakdown of cells, even 1:10 of Cremophor did not lyse cells. Studies of the effects of Cremophor on the uptake and efflux of DNR in normal and MDR cell types showed that Cremophor increases intracellular DNR primarily by locking the rapid efflux from the cells. This blockage of drug efflux may be mediated by a substantial alteration in the fluidity of cell membranes induced by Cremophor, as shown by decreased fluorescence anisotropy of a membrane probe. Consistent with these data, coinjection of adriamycin plus Cremophor into mice carrying a multidrug resistant P388 transplantable tumour significantly increased the survival time of the mice compared with adriamycin treatment alone. PMID:1637678

  15. Photosensitive Cationic Azobenzene Surfactants: Thermodynamics of Hydration and the Complex Formation with Poly(methacrylic acid).

    Science.gov (United States)

    Montagna, Maria; Guskova, Olga

    2018-01-09

    In this computational work, we investigate the photosensitive cationic surfactants with the trimethylammonium or polyamine hydrophilic head and the azobenzene-containing hydrophobic tail. The azobenzene-based molecules are known to undergo a reversible trans-cis-trans isomerization reaction when subjected to UV-visible light irradiation. Combining the density functional theory and the all-atom molecular dynamics simulations, the structural and the hydration properties of the trans- and the cis-isomers and their interaction with the oppositely charged poly(methacrylic acid) in aqueous solution are investigated. We establish and quantify the correlations of the molecular structure and the isomerization state of the surfactants and their hydrophilicity/hydrophobicity and the self-assembling altered by light. For this reason, we compare the hydration free energies of the trans- and the cis-isomers. Moreover, the investigations of the interaction strength between the azobenzene molecules and the polyanion provide additional elucidations of the recent experimental and theoretical studies on the light triggered reversible deformation behavior of the microgels and the polymer brushes loaded with azobenzene surfactants.

  16. Co-surfactant free microemulsions: Preparation, characterization and stability evaluation for food application.

    Science.gov (United States)

    Xu, Zhenbo; Jin, Jun; Zheng, Minying; Zheng, Yan; Xu, Xuebing; Liu, Yuanfa; Wang, Xingguo

    2016-08-01

    The aim of the study is to prepare co-surfactant free microalgal oil microemulsions and investigate their properties as well as processing stability for food application. The physicochemical characteristics of the microemulsions were investigated by dynamic light scattering (DLS), turbidity, conductivity, rheological measurements and transmission electron microscopy (TEM). Within the microemulsion region, when the surfactant to oil ratio was 9:1, the hydrodynamic diameter (Dh) was 18nm; when the surfactant to oil ratio was 7.5:1, the hydrodynamic diameter (Dh) was 50nm. Rheological studies proved that the microemulsion system was a pseudoplastic fluid, which followed a shear thinning flow behavior. The loss rate of docosahexaenoic acid (DHA) was less than 5%wt after ultra high temperature (UHT) and high temperature short time (HTST) thermal treatments. A high content of CaCl2 (10.0%wt) could not destroy the microemulsion system, and it could be stored at 4°C for two years. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Gels and lyotropic liquid crystals: using an imidazolium-based catanionic surfactant in binary solvents.

    Science.gov (United States)

    Cheng, Ni; Hu, Qiongzheng; Bi, Yanhui; Xu, Wenwen; Gong, Yanjun; Yu, Li

    2014-08-05

    The self-assembly behavior of an imidazolium-based catanionic surfactant, 1-butyl-3-methylimidazolium dodecylsulfate ([C4mim][C12H25SO4]), was investigated in water-ethylammonium nitrate (EAN) mixed solvents with different volume ratios. It is particular interesting that this simple surfactant could not only form lyotropic liquid crystals (LLC) with multimesophases, i.e., normal hexagonal (H1), lamellar liquid crystal (Lα), and reverse bicontinuous cubic phase (V2), in the water-rich environment but also act as an efficient low-molecular-weight gelator (LMWG) which gelated EAN-abundant binary media in a broad concentration range. The peculiar nanodisk cluster morphology of gels composed of similar bilayer units was first observed. FT-IR spectra and density functional theory (DFT) calculations reveal that strong H bonding and electrostatic interactions between EAN and the headgroups of [C4mim][C12H25SO4] are primarily responsible for gelation. The self-assembled gels displayed excellent mechanical strength and a thermoreversible sol-gel transition. It is for the first time that a rich variety of controllable ordered aggregates could be observed only by simply modulating the concentration of a single imidazolium-based catanionic surfactant or the ratio of mixed solvents. This environmentally friendly system is expected to have broad applications in various fields, such as materials science, drug delivery systems, and supramolecular chemistry.

  18. Effect of Surfactants on Gas Holdup in Shear-Thinning Fluids

    Directory of Open Access Journals (Sweden)

    Shaobai Li

    2017-01-01

    Full Text Available In this study, the gas holdup of bubble swarms in shear-thinning fluids was experimentally studied at superficial gas velocities ranging from 0.001 to 0.02 m·s−1. Carboxylmethyl cellulose (CMC solutions of 0.2 wt%, 0.6 wt%, and 1.0 wt% with sodium dodecyl sulfate (SDS as the surfactant were used as the power-law (liquid phase, and nitrogen was used as the gas phase. Effects of SDS concentration, rheological behavior, and physical properties of the liquid phase and superficial gas velocity on gas holdup were investigated. Results indicated that gas holdup increases with increasing superficial gas velocity and decreasing CMC concentration. Moreover, the addition of SDS in CMC solutions increased gas holdup, and the degree increased with the surfactant concentration. An empirical correlation was proposed for evaluating gas holdup as a function of liquid surface tension, density, effective viscosity, rheological property, superficial gas velocity, and geometric characteristics of bubble columns using the experimental data obtained for the different superficial gas velocities and CMC solution concentrations with different surfactant solutions. These proposed correlations reasonably fitted the experimental data obtained for gas holdup in this system.

  19. Phase Separation Kinetics in Isopycnic Mixtures of H2O/CO2/Ethoxylated Alcohol Surfactants

    Science.gov (United States)

    Lesemann, Markus; Paulaitis, Michael E.; Kaler, Eric W.

    1999-01-01

    Ternary mixtures of H2O and CO2 with ethoxylated alcohol (C(sub i)E(sub j)) surfactants form three coexisting liquid phases at conditions where two of the phases have equal densities (isopycnic phases). Isopycnic phase behavior has been observed for mixtures containing C8E5, C10E6, and C12E6 surfactants, but not for those mixtures containing either C4E1 or C8E3 surfactants. Pressure-temperature (PT) projections for this three-phase equilibrium were determined for H2O/CO2/C8E5 and H2O/CO2/C10E6 mixtures at temperatures from approximately 25 to 33 C and pressures between 90 and 350 bar. Measurements of the microstructure in H2O/CO2/C12E6 mixtures as a function of temperature (25-31 C), pressure (63.1-90.7 bar), and CO2 composition (0-3.9 wt%) have also been carried out to show that while micellar structure remains essentially un-changed, critical concentration fluctuations increase as the phase boundary and plait point are approached. In this report, we present our first measurements of the kinetics of isopycnic phase separation for ternary mixtures of H2O/CO2/C8E5.

  20. Impact of heterogeneous properties of soil and LNAPL on surfactant-enhanced capillary desaturation.

    Science.gov (United States)

    Robert, Thomas; Martel, Richard; Lefebvre, René; Lauzon, Jean-Marc; Morin, Annie

    2017-09-01

    This paper investigates low-concentration (soil permeability, pore-size distribution, mineralogy, light non-aqueous phase liquid (LNAPL) weathering and groundwater hardness were quantified through batch and soil column tests. Compatibility issues between the mixed mineralogy soils, hard groundwater, mixed LNAPL and usual anionic surfactants were observed. The selected solution was a Winsor type I system promoting an interfacial tension of 0.06mN/m between the site LNAPL and the amphoteric surfactant CAS in aqueous solution at pH12. Surfactant loses to adsorption and pore media plugging were observed in the fine soil fraction. The capillary desaturation curves (CDC) obtained with the column tests suggested mixed-wettability behavior. The soil permeability strongly influenced LNAPL recovery, as expressed by the relationship obtained between capillary numbers (N Ca ) and hydraulic gradients. In this case, the critical N Ca , marking the onset of capillary desaturation, could only be obtained with realistic hydraulic gradients in the coarse soil fraction. At those gradients, potential LNAPL recovery was 30% at the most. Unlike previously published CDCs, the relationship between N Ca (log-scale) and LNAPL recovery was not linear but dependant on residual LNAPL saturation. Copyright © 2017 Elsevier B.V. All rights reserved.