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Sample records for charge affect surfactant

  1. 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.

  2. Bending elasticity of charged surfactant layers: the effect of mixing.

    Science.gov (United States)

    Bergström, L Magnus

    2006-08-01

    Expressions have been derived from which the spontaneous curvature (H(0)), bending rigidity (k(c)), and saddle-splay constant (k(c)) of mixed monolayers and bilayers may be calculated from molecular and solution properties as well as experimentally available quantities such as the macroscopic hydrophobic-hydrophilic interfacial tension. Three different cases of binary surfactant mixtures have been treated in detail: (i) mixtures of an ionic and a nonionic surfactant, (ii) mixtures of two oppositely charged surfactants, and (iii) mixtures of two ionic surfactants with identical headgroups but different tail volumes. It is demonstrated that k(c)H(0), k(c), and k(c) for mixtures of surfactants with flexible tails may be subdivided into one contribution that is due to bending properties of an infinitely thin surface as calculated from the Poisson-Boltzmann mean field theory and one contribution appearing as a result of the surfactant film having a finite thickness with the surface of charge located somewhat outside the hydrophobic-hydrophilic interface. As a matter of fact, the picture becomes completely different as finite layer thickness effects are taken into account, and as a result, the spontaneous curvature is extensively lowered whereas the bending rigidity is raised. Furthermore, an additional contribution to k(c) is present for surfactant mixtures but is absent for k(c)H(0) and k(c). This contribution appears as a consequence of the minimization of the free energy with respect to the composition of a surfactant layer that is open in the thermodynamic sense and must always be negative (i.e., k(c) is generally found to be brought down by the process of mixing two or more surfactants). The magnitude of the reduction of k(c) increases with increasing asymmetry between two surfactants with respect to headgroup charge number and tail volume. As a consequence, the bending rigidity assumes the lowest values for layers formed in mixtures of two oppositely charged

  3. Role of the charge, carbon chain length, and content of surfactant on the skin penetration of meloxicam-loaded liposomes

    Directory of Open Access Journals (Sweden)

    Duangjit S

    2014-04-01

    Full Text Available Sureewan Duangjit,1,2 Boonnada Pamornpathomkul,1 Praneet Opanasopit,1 Theerasak Rojanarata,1 Yasuko Obata,2 Kozo Takayama,2 Tanasait Ngawhirunpat11Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand; 2Department of Pharmaceutics, Hoshi University, Shinagawa-ku, Tokyo, JapanAbstract: The objective of this study was to investigate the influence of surfactant charge, surfactant carbon chain length, and surfactant content on the physicochemical characteristics (ie, vesicle size, zeta potential, elasticity, and entrapment efficiency, morphology, stability, and in vitro skin permeability of meloxicam (MX-loaded liposome. Moreover, the mechanism for the liposome-enhanced skin permeation of MX was determined by Fourier transform infrared spectroscopy and differential scanning calorimetry. The model formulation used in this study was obtained using a response surface method incorporating multivariate spline interpolation (RSM-S. Liposome formulations with varying surfactant charge (anionic, neutral, and cationic, surfactant carbon chain length (C4, C12, and C16, and surfactant content (10%, 20%, and 29% were prepared. The formulation comprising 29% cationic surfactant with a C16 chain length was found to be the optimal liposome for the transdermal delivery of MX. The skin permeation flux of the optimal formulation was 2.69-fold higher than that of a conventional liposome formulation. Our study revealed that surfactants affected the physicochemical characteristics, stability, and skin permeability of MX-loaded liposomes. These findings provide important fundamental information for the development of liposomes as transdermal drug delivery systems.Keywords: optimal liposome, optimization, transdermal drug delivery, surfactant charge, surfactant carbon chain length, surfactant content

  4. Foaming and foam stability for mixed polymer-surfactant solutions: effects of surfactant type and polymer charge.

    Science.gov (United States)

    Petkova, R; Tcholakova, S; Denkov, N D

    2012-03-20

    Solutions of surfactant-polymer mixtures often exhibit different foaming properties, compared to the solutions of the individual components, due to the strong tendency for formation of polymer-surfactant complexes in the bulk and on the surface of the mixed solutions. A generally shared view in the literature is that electrostatic interactions govern the formation of these complexes, for example between anionic surfactants and cationic polymers. In this study we combine foam tests with model experiments to evaluate and explain the effect of several polymer-surfactant mixtures on the foaminess and foam stability of the respective solutions. Anionic, cationic, and nonionic surfactants (SDS, C(12)TAB, and C(12)EO(23)) were studied to clarify the role of surfactant charge. Highly hydrophilic cationic and nonionic polymers (polyvinylamine and polyvinylformamide, respectivey) were chosen to eliminate the (more trivial) effect of direct hydrophobic interactions between the surfactant tails and the hydrophobic regions on the polymer chains. Our experiments showed clearly that the presence of opposite charges is not a necessary condition for boosting the foaminess and foam stability in the surfactant-polymer mixtures studied. Clear foam boosting (synergistic) effects were observed in the mixtures of cationic surfactant and cationic polymer, cationic surfactant and nonionic polymer, and anionic surfactant and nonionic polymer. The mixtures of anionic surfactant and cationic polymer showed improved foam stability, however, the foaminess was strongly reduced, as compared to the surfactant solutions without polymer. No significant synergistic or antagonistic effects were observed for the mixture of nonionic surfactant (with low critical micelle concentration) and nonionic polymer. The results from the model experiments allowed us to explain the observed trends by the different adsorption dynamics and complex formation pattern in the systems studied.

  5. Recent progress of the characterization of oppositely charged polymer/surfactant complex in dilution deposition system.

    Science.gov (United States)

    Miyake, M

    2017-01-01

    A mixture of oppositely charged polymer and surfactants changes the solubilized state, having a complex precipitation region at the composition of electric neutralization. This complex behavior has been applied to surface modification in the fields of health care and cosmetic products such as conditioning shampoos, as a dilution-deposition system in which the polymer/surfactant mixture at the higher surfactant concentration precipitates the insoluble complex by dilution. A large number of studies over many years have revealed the basic coacervation behavior and physicochemical properties of complexes. However, the mechanism by which a precipitated complex performs surface modification is not well understood. The precipitation region and the morphology of precipitated complex that are changed by molecular structure and additives affect the performance. Hydrophilic groups such as the EO unit in polymers and surfactants, the mixing of nonionic or amphoteric surfactant and nonionic polymer, and the addition of low polar solvent influence the complex precipitation region. Furthermore, the morphology of precipitated complex is formed by crosslinking and aggregating among polymers in the dilution process, and characterizes the performance of products. The polymer chain density in precipitated complex is determined by the charges of both the polymer and surfactant micelle and the conformation of polymer. As a result, the morphology of precipitated complexes is changed from a closely packed film to looser meshes, and/or to small particles, and it is possible for the morphology to control the rheological properties and the amount of adsorbed silicone. In the future, further investigation of the relationships between the morphology and performance is needed.

  6. Effect of surfactant hydrophile-lipophile balance (HLB) value on mineral oxide charging in apolar media.

    Science.gov (United States)

    Gacek, Matthew Michael; Berg, John C

    2015-07-01

    The current work examines the role of surfactant hydrophile-lipophile balance (HLB) on the ability for surfactant reverse micelles to impart charge to particles dispersed in an apolar medium, a study motivated by a number of applications that seek to maximize particle charge in such systems. Previous investigations have shown that relative acid-base properties of the particles and surfactants, as well as surfactant concentration and trace water content, all play a major role in the particle charge obtained. However, the ability of a surfactant to stabilize charge in reverse micelles is also an important aspect of creating charge on a particle surface. It has been previously shown that surfactant HLB value is an important parameter in assessing the size of the polar core of the reverse micelles, thereby impacting the total charge that is generated in the bulk solution as determined by conductivity. In the current study, this theory is extended to investigate the impact on particle charging. To accomplish this, the electrophoretic mobility is determined for a series of mineral oxides dispersed in Isopar-L with either Span 20, Span 80, or Span 85. These three surfactants all have the same head group chemistry, but their HLB value ranges from 1.8 to 8.6. It is found that the maximum observed particle electrophoretic mobility does scale directly with the HLB of the accompanying surfactant. This indicates that there is a direct correlation between a surfactant's ability to stabilize charge and its ability to impart charge to a particle. However, the largest HLB surfactant, Span 20, also exhibited a large amount of charge screening or neutralization at larger surfactant concentrations. This highlights the competition between particle charging and micelle-micelle charging that remains one of the largest obstacles to maximizing particle charge in apolar systems.

  7. Breakup of an electrified viscous thread with charged surfactants

    Science.gov (United States)

    Conroy, D. T.; Matar, O. K.; Craster, R. V.; Papageorgiou, D. T.

    2011-02-01

    The dynamics and breakup of electrified viscous jets in the presence of ionic surfactants at the interface are investigated theoretically. Axisymmetric configurations are considered and the jet is surrounded by a concentrically placed cylindrical electrode, which is held at a constant voltage potential. The annular region between the jet and the electrode is taken to be a hydrodynamically passive dielectric medium and an electric field is set up there and drives the flow, along with other physical mechanisms including capillary instability and viscous effects. The jet fluid is taken to be a symmetric electrolyte and proper modeling of the cationic and anionic species is used by considering the Nernst-Planck equations in order to find the volume charge density that influences the electric field in the jet. A positively charged insoluble surfactant is present at the interface, and its evolution, as well as the resulting value of the local surface tension coefficient, is coupled with the voltage potential at the interface. The resulting coupled nonlinear systems are derived and analytical progress is made by carrying out a nonlinear slender jet approximation. The reduced model is described by a number of hydrodynamic, electrical, and electrokinetic parameters, and an extensive computational study is undertaken to elucidate the dynamics along with allied linear properties. It is established that the jet ruptures in finite time provided the outer electrode is sufficiently far away, and numerous examples are given where the dimensionless parameters can be used to control the size of the satellite drops that form beyond the topological transition, as well as the time to break up. It is also shown that pinching solutions follow the self-similar dynamics of clean viscous jets at times close to the breakup time. Finally, a further asymptotic theory is developed for large Debye layers to produce an additional model that incorporates the effects of surface charge diffusion

  8. Small angle neutron scattering study of mixed micelles of oppositely charged surfactants

    Indian Academy of Sciences (India)

    J V Joshi; V K Aswal; P S Goyal

    2008-11-01

    Structures of mixed micelles of oppositely charged surfactants dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulphate (SDS) have been studied using small angle neutron scattering. The concentration of one of the components was kept fixed (0.3 M) and that of another varied in the range 0 to 0.1 M. The aggregation number and micellar size increase and fractional charge decreases dramatically with the addition of small amount of oppositely charged surfactant. The effect of addition of SDS on DTAB is significantly different from that of the addition of DTAB on SDS. The contrast variation SANS experiments using deuterated surfactant suggests the homogeneous mixing of two components in mixed micellar system.

  9. Cationic surfactants derived from lysine: effects of their structure and charge type on antimicrobial and hemolytic activities.

    Science.gov (United States)

    Colomer, A; Pinazo, A; Manresa, M A; Vinardell, M P; Mitjans, M; Infante, M R; Pérez, L

    2011-02-24

    Three different sets of cationic surfactants from lysine have been synthesized. The first group consists of three monocatenary surfactants with one lysine as the cationic polar head with one cationic charge. The second consists of three monocatenary surfactants with two amino acids as cationic polar head with two positive charges. Finally, four gemini surfactants were synthesized in which the spacer chain and the number and type of cationic charges have been regulated. The micellization process, antimicrobial activity, and hemolytic activity were evaluated. The critical micelle concentration was dependent only on the hydrophobic character of the molecules. Nevertheless, the antimicrobial and hemolytic activities were related to the structure of the compounds as well as the type of cationic charges. The most active surfactants against the bacteria were those with a cationic charge on the trimethylated amino group, whereas all of these surfactants showed low hemolytic character.

  10. Effect of laundry surfactants on surface charge and colloidal stability of silver nanoparticles.

    Science.gov (United States)

    Skoglund, Sara; Lowe, Troy A; Hedberg, Jonas; Blomberg, Eva; Wallinder, Inger Odnevall; Wold, Susanna; Lundin, Maria

    2013-07-16

    The stability of silver nanoparticles (Ag NPs) potentially released from clothing during a laundry cycle and their interactions with laundry-relevant surfactants [anionic (LAS), cationic (DTAC), and nonionic (Berol)] have been investigated. Surface interactions between Ag NPs and surfactants influence their speciation and stability. In the absence of surfactants as well as in the presence of LAS, the negatively charged Ag NPs were stable in solution for more than 1 day. At low DTAC concentrations (≤1 mM), DTAC-Ag NP interactions resulted in charge neutralization and formation of agglomerates. The surface charge of the particles became positive at higher concentrations due to a bilayer type formation of DTAC that prevents from agglomeration due to repulsive electrostatic forces between the positively charged colloids. The adsorption of Berol was enhanced when above its critical micelle concentration (cmc). This resulted in a surface charge close to zero and subsequent agglomeration. Extended DLVO theory calculations were in compliance with observed findings. The stability of the Ag NPs was shown to depend on the charge and concentration of the adsorbed surfactants. Such knowledge is important as it may influence the subsequent transport of Ag NPs through different chemical transients and thus their potential bioavailability and toxicity.

  11. Electrostatic charge on spray droplets of aqueous surfactant solutions

    OpenAIRE

    POLAT, Mehmet; Polat, Hürriyet; Chander, Subhash

    2000-01-01

    Electrostatic charges on individual spray droplets were measured using a refined form of the Millikan oil drop method. The measurement system consisted of three main sections; a droplet generation cell, a settling column and a charge measurement chamber. The trajectories required for calculation of charge were determined using a high-speed motion analyzer coupled to a long-focal-length microscope. Charges on droplets were manipulated by the addition of surface-active agents into the spray sol...

  12. Rheological properties of ovalbumin hydrogels as affected by surfactants addition.

    Science.gov (United States)

    Hassan, Natalia; Messina, Paula V; Dodero, Veronica I; Ruso, Juan M

    2011-04-01

    The gel properties of ovalbumin mixtures with three different surfactants (sodium perfluorooctanoate, sodium octanoate and sodium dodecanoate) have been studied by rheological techniques. The gel elasticities were determined as a function of surfactant concentration and surfactant type. The fractal dimension of the formed structures was evaluated from plots of storage modulus against surfactant concentration. The role of electrostatic, hydrophobic and disulfide SS interactions in these systems has been demonstrated to be the predominant. The viscosity of these structures tends to increase with surfactant concentration, except for the fluorinated one. Unfolded ovalbumin molecules tend to form fibrillar structures that tend to increase with surfactant concentration, except for the fluorinated one. This fact has been related to the particular nature of this molecule.

  13. BINDING OF IONIC SURFACTANTS ON OPPOSITELY CHARGED POLYELECTROLYTES OBSERVED BY FLUORESCENCE METHODS

    Institute of Scientific and Technical Information of China (English)

    Zhen Tong; Chao-yang Wang; Bi-ye Ren; Xin-xing Liu; Fang Zeng

    2003-01-01

    Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C12E8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymersurfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.

  14. Charged particles interacting with a mixed supported lipid bilayer as a biomimetic pulmonary surfactant.

    Science.gov (United States)

    Munteanu, B; Harb, F; Rieu, J P; Berthier, Y; Tinland, B; Trunfio-Sfarghiu, A-M

    2014-08-01

    This study shows the interactions of charged particles with mixed supported lipid bilayers (SLB) as biomimetic pulmonary surfactants. We tested two types of charged particles: positively charged and negatively charged particles. Two parameters were measured: adsorption density of particles on the SLB and the diffusion coefficient of lipids by FRAPP techniques as a measure of interaction strength between particles and lipids. We found that positively charged particles do not adsorb on the bilayer, probably due to the electrostatic repulsion between positively charged parts of the lipid head and the positive groups on the particle surface, therefore no variation in diffusion coefficient of lipid molecules was observed. On the contrary, the negatively charged particles, driven by electrostatic interactions are adsorbed onto the supported bilayer. The adsorption of negatively charged particles increases with the zeta-potential of the particle. Consecutively, the diffusion coefficient of lipids is reduced probably due to binding onto the lipid heads which slows down their Brownian motion. The results are directly relevant for understanding the interactions of particulate matter with pulmonary structures which could lead to pulmonary surfactant inhibition or deficiency causing severe respiratory distress or pathologies.

  15. Phase behavior and molecular thermodynamics of coacervation in oppositely charged polyelectrolyte/surfactant systems: a cationic polymer JR 400 and anionic surfactant SDS mixture.

    Science.gov (United States)

    Li, Dongcui; Kelkar, Manish S; Wagner, Norman J

    2012-07-17

    Coacervation in mixtures of polyelectrolytes and surfactants with opposite charge is common in nature and is also technologically important to consumer health care products. To understand the complexation behavior of these systems better, we combine multiple experimental techniques to systematically study the polymer/surfactant binding interactions and the phase behavior of anionic sodium dodecyl sulfate (SDS) surfactant in cationic JR 400 polymer aqueous solutions. The phase-behavior study resolves a discrepancy in the literature by identifying a metastable phase between the differing redissolution phase boundaries reported in the literature for the surfactant-rich regime. Isothermal titration calorimetry analyzed within the framework of the simple Satake-Yang model identifies binding parameters for the surfactant-lean phase, whereas a calculation for polymer-bound micelles coexisting with free micelles is analyzed in the surfactant-rich redissolution regime. This analysis provides a preliminary understanding of the interactions governing the observed phase behavior. The resulting thermodynamic properties, including binding constants and the molar Gibbs free energies, enthalpies, and entropies, identify the relative importance of both hydrophobic and electrostatic interactions and provide a first approximation for the corresponding microstructures in the different phases. Our study also addresses the stability and metastability of oppositely charged polyelectrolytes and surfactant mixtures.

  16. THE EFFECT OF CHARGE AND CHEMICAL STRUCTURE OF CATIONIC SURFACTANTS ON LASER TONER AGGLOMERATION UNDER ALKALINE PULPING CONDITIONS

    Directory of Open Access Journals (Sweden)

    Jie Jiang,

    2012-02-01

    Full Text Available Laboratory-scale agglomeration experiments followed by image analysis were used to evaluate the effectiveness of different cationic surfactants on the 1-octadecanol agglomeration of a negatively charged laser toner. Various types of surfactants with different geometric structures were investigated. It was found that this toner became agglomerated under neutral pulping conditions, but it did not agglomerate under alkaline conditions at all. A small amount of the cationic surfactant compensated for the agglomeration disruption caused by the negative surface charge of the toner and made this toner agglomerate very well. These cationic surfactants consist of a chemical structure of C12 to C18 saturated alkyl hydrophobic chains. The positive charge of these surfactants played the major role in alleviating agglomeration disruption. Additionally, an extra phenol group on these surfactants contributed only minor advantages for toner agglomeration in the presence of 1-octadecanol. The best co-agglomeration performance occurred within a very narrow range of similar total positive charge densities based on the total toner weight. It was also found that this positive charge effect could not be applied to the chemical compounds of high molecular weight polymeric materials.

  17. Electrostatic Screening and Charge Correlation Effects in Micellization of Ionic Surfactants

    KAUST Repository

    Jusufi, Arben

    2009-05-07

    We have used atomistic simulations to study the role of electrostatic screening and charge correlation effects in self-assembly processes of ionic surfactants into micelles. Specifically, we employed grand canonical Monte Carlo simulations to investigate the critical micelle concentration (cmc), aggregation number, and micellar shape in the presence of explicit sodium chloride (NaCl). The two systems investigated are cationic dodecyltrimethylammonium chloride (DTAC) and anionic sodium dodecyl sulfate (SDS) surfactants. Our explicit-salt results, obtained from a previously developed potential model with no further adjustment of its parameters, are in good agreement with experimental data for structural and thermodynamic micellar properties. We illustrate the importance of ion correlation effects by comparing these results with a Yukawa-type surfactant model that incorporates electrostatic screening implicitly. While the effect of salt on the cmc is well-reproduced even with the implicit Yukawa model, the aggregate size predictions deviate significantly from experimental observations at low salt concentrations. We attribute this discrepancy to the neglect of ion correlations in the implicit-salt model. At higher salt concentrations, we find reasonable agreement of the Yukawa model with experimental data. The crossover from low to high salt concentrations is reached when the electrostatic screening length becomes comparable to the headgroup size. © 2009 American Chemical Society.

  18. Analyzing Affect of Image Charge in Space Charge Effect

    Institute of Scientific and Technical Information of China (English)

    ZhangXueying; XuHushan; JiaFei; LiWenfei

    2003-01-01

    There is an increasing requirement of high injection current and highly charged ion beams for accelerators at many laboratories, such as CERN, GSI, GANIL and IMP, with the development of super-conducting ECR source in recent.years. In this case, the space charge effect becomes a major concern when the beam current is as high as tens of mA. In fact, the faradic field induced by the image charges will be come into the metallic surfaces while the beams are transported in a vacuum tube or in between two plates. In order to ensure studying the space charge effect in reason, it is necessary to investigate the effect from such a field.

  19. Interaction of cationic hydrophobic surfactants at negatively charged surfaces investigated by atomic force microscopy.

    Science.gov (United States)

    McNamee, Cathy E; Butt, Hans-Jürgen; Higashitani, Ko; Vakarelski, Ivan U; Kappl, Michael

    2009-10-06

    Atomic force microscopy was used to study the adsorption of the surfactant octadecyl trimethyl ammonium chloride (C18TAC) at a low concentration (0.03 mM) to negatively charged surfaces in water. Atomic force microscopy tips were functionalized with dimethyloctadecyl(3-tripropyl)ammonium chloride (C18TAC-si) or N-trimethoxysilylpropyl-N,N,N-trimethylammomium chloride (hydrophilpos-si) to facilitate imaging of the adsorbed surfactant without artifacts. Tapping mode images and force measurements revealed C18TAC patches, identified as partial surfactant bilayers or hemimicelles. The forces controlling the adsorption process of the C18TAC to a negatively charged surface were investigated by measuring the forces between a C18TAC-si or a hydrophilpos-si tip and a silica surface in the presence of varying concentrations of either NaCl or NaNO3. Screening of forces with an increasing NaCl concentration was observed for the C18TAC-si and hydrophilpos-si tips, proving an electrostatic contribution. Screening was also observed for the hydrophilpos-si tip in NaNO3, whereas a long-range attraction was observed for the C18TAC-si tip for all NaNO3 concentrations. These results indicate that screening of the forces for the C18TAC-si tip depended on the type and/or size of the anion, possibly due to a different probability of the anions to enter the silane layers. The interaction of C18TAC patches with C18TAC-si tips in the presence of NaCl and the interaction of the patches with hydrophilpos-si tips in either NaCl or NaNO3 were repulsive and independent of the number of force curves measured, indicating a stable, positively charged C18TAC patch. However, the forces measured between the patches and a C18TAC-si tip in NaNO3 depended on the number of force curves measured, indicating a change in patch structure induced by the first interaction.

  20. Understanding self-assembly of charged-neutral block copolymer (BCP) and surfactant complexes using molecular dynamics (MD) simulation

    Science.gov (United States)

    Goswami, Monojoy; Sumpter, Bobby; Kilbey, Michael

    Here we report the formation of phase separated BCP-surfactant complexes resulting from the electrostatic self-assembly of charge-neutral block copolymers with oppositely charged surfactants. Complexation behaviors of oppositely charged polyelectrolytes has gained considerable attention in the field of soft condensed matter physics due to their potential application as functional nanomaterials for batteries, wastewater treatment and drug delivery systems. Numerous experiments have examined the self-assembled structures resulting from complexation of charge-neutral BCP and surfactants, however, there is a lack of comprehensive understanding at the fundamental level. To help bridge this gap, we use, MD simulations to study self-assembly and dynamics of the BCP-surfactant complex at the molecular level. Our results show an overcharging effect in BCPs with hydrophobic neutral blocks and a formation of core-shell colloidal structure. Hydrophilic neutral blocks, on the other hand, show stable, hairy colloidal structures with neutral blocks forming a loosely-bound, fuzzy outer layer. Our results qualitatively agree with previous SANS and SAXS experiments. This work was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Materials Science and Engineering Division.

  1. Photophysical study of a charge transfer oxazole dye in micelles: Role of surfactant headgroups

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Jyotirmay [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India); Sarkar, Yeasmin; Parui, Partha Pratim [Department of Chemistry, Jadavpur University, Kolkata 700032 (India); Chakraborty, Sandipan [Department of Microbiology, University of Calcutta, Kolkata 700019 (India); Biswas, Suman [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India); Das, Ranjan, E-mail: ranjan.das68@gmail.com [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India)

    2015-07-15

    Photophysics of 5-(4′′-dimethylaminophenyl)-2-(4′-sulfophenyl)oxazole, sodium salt (DMO) which undergoes intramolecular charge transfer in the excited state was studied in micelles. In the cationic and the nonionic micelles, significantly higher fluorescence quantum yield is observed in comparison to the anionic micelles, due to much lower accessibility of DMO to the water molecules in the former micelles than the latter. Time-resolved fluorescence decays were characterized by a fast (τ{sub 1}) and a slow (τ{sub 2}) component of decay in all the micelles. The fast decay component (τ{sub 1}) increases significantly in going from the anionic micelles to the cationic micelles, because of the poorly hydrated headgroup region of the latter micelles compared to the former. Furthermore, much higher value of the slow component of decay (τ{sub 2}) is observed for the cationic and the neutral micelles than the anionic micelles. This is attributed to the increased penetration of water molecules into the micellar core of the anionic micelles compared to the cationic and the neutral micelles. - Highlights: • Photophysics of the fluorophore are remarkably different in the cationic and the anionic micelles. • Differential hydration of the surfactant headgroups gives rise to significantly different fluorescence quantum yield and lifetime in oppositely charged micelles. • Electrostatic interactions fine tune location of the fluorophore in the micelle–water interface of ionic micelles.

  2. Interaction of bolaform surfactants with p-sulfonatocalix[4]arene: the role of two positive charges in the binding.

    Science.gov (United States)

    Francisco, Vitor; Garcia-Rio, Luis

    2014-06-17

    The inclusion binding manners of bolaform surfactants of type C(n)R6(2+) 2Br(-) with different spacer lengths (n = 6, 12) and terminal headgroup volumes (R = methyl, ethyl) by p-sulfonatocalix[4]arene were studied. The combination of ITC parameters (binding constants and complexation enthalpy and entropy) and NMR chemical shifts and NOE cross-peaks obtained upon complexation allows us to propose different binding modes. The results point out that the spacer length has an influence on the binding stoichiometry. The bolaforms with larger spacer lengths between polar head groups enable the formation of 2:1 complexes in addition to 1:1, while with the shorter spacer they form only 1:1 complexes. On the other hand, the formation of 1:1 complexes is not affected by the headgroup volume or the spacer length of the bolaform. Unexpectedly, a complex binding mode was observed where both positive charged terminal groups of the bolaform are accommodated in the cavity of the calixarene. The inclusion of both terminal groups of the guests can be related to its own structure but also evidence the high flexibility of the calixarene.

  3. Calix-arene silver nanoparticles interactions with surfactants are charge, size and critical micellar concentration dependent.

    Science.gov (United States)

    Tauran, Yannick; Brioude, Arnaud; Shahgaldian, Patrick; Cumbo, Alessandro; Kim, Beomjoon; Perret, Florent; Coleman, Anthony W; Montasser, Imed

    2012-10-04

    The interactions of silver nanoparticles capped by various calix[n]arenes bearing sulphonate groups at the para and/or phenolic faces with cationic, neutral and anionic surfactants have been studied. Changes in the plasmonic absorption show that only the calix[4]arene derivatives sulphonated at the para-position interact and then only with cationic surfactants. The interactions follow the CMC values of the surfactants either as simple molecules or mixed micelles.

  4. Steroidal Surfactants: Detection of Premicellar Aggregation, Secondary Aggregation Changes in Micelles, and Hosting of a Highly Charged Negative Substance.

    Science.gov (United States)

    Barnadas-Rodríguez, Ramon; Cladera, Josep

    2015-08-25

    CHAPSO and CHAPS are zwitterionic surfactants derived from bile salts which are usually employed in protein purification and for the preparation of liposomes and bicelles. Despite their spread use, there are significant discrepancies on the critical concentrations that determine their aggregation behavior. In this work, we study the interaction between these surfactants with the negative fluorescent dye pyranine (HPTS) by absorbance, fluorescence, and infrared spectrometry to establish their concentration-dependent aggregation. For the studied surfactants, we detect three critical concentrations showing their concentration-dependent presence as a monomeric form, premicellar aggregates, micelles, and a second type of micelle in aqueous medium. The nature of the interaction of HPTS with the surfactants was studied using analogues of their tails and the negative bile salt taurocholate (TC) as reference for the sterol ring. The results indicate that the chemical groups involved are the hydroxyl groups of the polar face of the sterol ring and the sulfonate groups of the dye. This interaction causes not only the incorporation of the negative dye in CHAPSO and CHAPS micelles but also its association with their premicellar aggregates. Surprisingly, this hosting behavior for a negative charged molecule was also detected for the negative bile salt TC, bypassing, in this way, the electrostatic repulsion between the guest and the host.

  5. Kolliphor surfactants affect solubilization and bioavailability of fenofibrate. Studies of in vitro digestion and absorption in rats

    DEFF Research Database (Denmark)

    Berthelsen, Ragna; Holm, Rene; Jacobsen, Jette

    2015-01-01

    formulations only comprised an aqueous micellar solution of the model drug (fenofibrate) in varying concentrations (2–25% (w/v)) of the three tested surfactants. Increased concentrations of Kolliphor ELP and EL led to increased fenofibrate AUC0–24h values. For the Kolliphor RH40 formulations, an apparent...... fenofibrate absorption optimum was seen at 15% (w/v) surfactant, displaying both the highest AUC0–24h and Cmax. The reduced absorption of fenofibrate from the formulation containing the highest level of surfactant (25% w/v) was thought to be caused by some degree of trapping within Kolliphor RH40 micelles....... In vitro, Kolliphor ELP and EL were found to be more prone to digestion than Kolliphor RH40, though not affecting the in vivo results. The highest fenofibrate bioavailability was attained from formulations with high Kolliphor ELP/EL levels (25% (w/v)), indicating that these surfactants are the better...

  6. Internal charge transfer based ratiometric interaction of anionic surfactant with calf thymus DNA bound cationic surfactant: Study I

    Science.gov (United States)

    Mukherjee, Abhijit; Chaudhuri, Tandrima; Moulik, Satya Priya; Banerjee, Manas

    2016-01-01

    Cetyl trimethyl ammonium bromide (CTAB) binds calf thymus (ct-) DNA like anionic biopolymers electrostatically and established equilibrium both in the ground as well as in excited state in aqueous medium at pH 7. Anionic sodium dodecyl sulfate (SDS) does not show even hydrophobic interaction with ct-DNA at low concentration. On contrary, SDS can establish well defined equilibrium with DNA bound CTAB in ground state where the same CTAB-DNA isosbestic point reappears. First report of internal charge transfer (ICT) based binding of CTAB with ct-DNA as well as ICT based interaction of anionic SDS with DNA bound CTAB that shows dynamic quenching contribution also. The reappearance of anodic peak and slight increase in cathodic peak current with increasing concentration (at lower range) of anionic SDS, possibly reflect the release of CTAB from DNA bound CTAB by SDS.

  7. Internal charge transfer based ratiometric interaction of anionic surfactant with calf thymus DNA bound cationic surfactant: Study I.

    Science.gov (United States)

    Mukherjee, Abhijit; Chaudhuri, Tandrima; Moulik, Satya Priya; Banerjee, Manas

    2016-01-01

    Cetyl trimethyl ammonium bromide (CTAB) binds calf thymus (ct-) DNA like anionic biopolymers electrostatically and established equilibrium both in the ground as well as in excited state in aqueous medium at pH 7. Anionic sodium dodecyl sulfate (SDS) does not show even hydrophobic interaction with ct-DNA at low concentration. On contrary, SDS can establish well defined equilibrium with DNA bound CTAB in ground state where the same CTAB-DNA isosbestic point reappears. First report of internal charge transfer (ICT) based binding of CTAB with ct-DNA as well as ICT based interaction of anionic SDS with DNA bound CTAB that shows dynamic quenching contribution also. The reappearance of anodic peak and slight increase in cathodic peak current with increasing concentration (at lower range) of anionic SDS, possibly reflect the release of CTAB from DNA bound CTAB by SDS.

  8. Discrete space charge affected field emission: Flat and hemisphere emitters

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Kevin L., E-mail: kevin.jensen@nrl.navy.mil [Code 6854, Naval Research Laboratory, Washington, DC 20375 (United States); Shiffler, Donald A.; Tang, Wilkin [Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States); Rittersdorf, Ian M. [Code 6770, Naval Research Laboratory, Washington, DC 20375 (United States); Lebowitz, Joel L. [Department of Mathematics and Department of Physics, Rutgers University, Piscataway, New Jersey 08854-8019 (United States); Harris, John R. [U.S. Navy Reserve, New Orleans, Louisiana 70143 (United States); Lau, Y. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Petillo, John J. [Leidos, Billerica, Massachusetts 01821 (United States); Luginsland, John W. [Physics and Electronics Directorate, AFOSR, Arlington, Virginia 22203 (United States)

    2015-05-21

    Models of space-charge affected thermal-field emission from protrusions, able to incorporate the effects of both surface roughness and elongated field emitter structures in beam optics codes, are desirable but difficult. The models proposed here treat the meso-scale diode region separate from the micro-scale regions characteristic of the emission sites. The consequences of discrete emission events are given for both one-dimensional (sheets of charge) and three dimensional (rings of charge) models: in the former, results converge to steady state conditions found by theory (e.g., Rokhlenko et al. [J. Appl. Phys. 107, 014904 (2010)]) but show oscillatory structure as they do. Surface roughness or geometric features are handled using a ring of charge model, from which the image charges are found and used to modify the apex field and emitted current. The roughness model is shown to have additional constraints related to the discrete nature of electron charge. The ability of a unit cell model to treat field emitter structures and incorporate surface roughness effects inside a beam optics code is assessed.

  9. Ionic Surfactant Binding to pH-Responsive Polyelectrolyte Brush-Grafted Nanoparticles in Suspension and on Charged Surfaces.

    Science.gov (United States)

    Riley, John K; An, Junxue; Tilton, Robert D

    2015-12-29

    The interactions between silica nanoparticles grafted with a brush of cationic poly(2-(dimethylamino) ethyl methacrylate) (SiO2-g-PDMAEMA) and anionic surfactant sodium dodecyl sulfate (SDS) is investigated by dynamic light scattering, electrophoretic mobility, quartz crystal microbalance with dissipation, ellipsometry, and atomic force microscopy. SiO2-g-PDMAEMA exhibits pH-dependent charge and size properties which enable the SDS binding to be probed over a range of electrostatic conditions and brush conformations. SDS monomers bind irreversibly to SiO2-g-PDMAEMA at low surfactant concentrations (∼10(-4) M) while exhibiting a pH-dependent threshold above which cooperative, partially reversible SDS binding occurs. At pH 5, SDS binding induces collapse of the highly charged and swollen brush as observed in the bulk by DLS and on surfaces by QCM-D. Similar experiments at pH 9 suggest that SDS binds to the periphery of the weakly charged and deswollen brush and produces SiO2-g-PDMAEMA/SDS complexes with a net negative charge. SiO2-g-PDMAEMA brush collapse and charge neutralization is further confirmed by colloidal probe AFM measurements, where reduced electrosteric repulsions and bridging adhesion are attributed to effects of the bound SDS. Additionally, sequential adsorption schemes with SDS and SiO2-g-PDMAEMA are used to enhance deposition relative to SiO2-g-PDMAEMA direct adsorption on silica. This work shows that the polyelectrolyte brush configuration responds in a more dramatic fashion to SDS than to pH-induced changes in ionization, and this can be exploited to manipulate the structure of adsorbed layers and the corresponding forces of compression and friction between opposing surfaces.

  10. Factors Affecting Sensitivity of Variable Charge Soils to Acid Rain

    Institute of Scientific and Technical Information of China (English)

    WANGJING-HUA

    1995-01-01

    The sensitivity of a large number of variable charge soils to acid rain was evaluated through examining pH-H2SO4 input curves.Two derivative parameters,the consumption of hydrogen ions by the soil and the acidtolerant limit as defined as the quantity of sulfuric acid required to bring the soil to pH 3.5 in a 0.001mol L-1 Ca(NO3)2 solution,were used.The sensitivity of variable charge soils was higher than that of constant charge soils,due to the predominance of kaolinite in clay mineralogical composition.Among these soils the sensitivity was generally of the order lateritic red soil>red soil> latosol.For a given type of soil within the same region the sensitivity was affected by parent material,due to differences in clay minerals and texture.The sensitivity of surface soil may be lower or higher than that of subsiol,depending on whether organic matter or texture plays the dominant role in determining the buffering capacity.Paddy soils consumed more acid within lower range of acid input when compared with upland soils,due to the presence of more exchangeable bases,but consumed less acid within higher acid input range,caused by the decrease in clay content.

  11. Surfactant functionalization induces robust, differential adhesion of tumor cells and blood cells to charged nanotube-coated biomaterials under flow.

    Science.gov (United States)

    Mitchell, Michael J; Castellanos, Carlos A; King, Michael R

    2015-07-01

    The metastatic spread of cancer cells from the primary tumor to distant sites leads to a poor prognosis in cancers originating from multiple organs. Increasing evidence has linked selectin-based adhesion between circulating tumor cells (CTCs) and endothelial cells of the microvasculature to metastatic dissemination, in a manner similar to leukocyte adhesion during inflammation. Functionalized biomaterial surfaces hold promise as a diagnostic tool to separate CTCs and potentially treat metastasis, utilizing antibody and selectin-mediated interactions for cell capture under flow. However, capture at high purity levels is challenged by the fact that CTCs and leukocytes both possess selectin ligands. Here, a straightforward technique to functionalize and alter the charge of naturally occurring halloysite nanotubes using surfactants is reported to induce robust, differential adhesion of tumor cells and blood cells to nanotube-coated surfaces under flow. Negatively charged sodium dodecanoate-functionalized nanotubes simultaneously enhanced tumor cell capture while negating leukocyte adhesion, both in the presence and absence of adhesion proteins, and can be utilized to isolate circulating tumor cells regardless of biomarker expression. Conversely, diminishing nanotube charge via functionalization with decyltrimethylammonium bromide both abolished tumor cell capture while promoting leukocyte adhesion.

  12. Chemical Behavior of Cadmium in Purple Soil as Affected by Surfactants and EDTA

    Institute of Scientific and Technical Information of China (English)

    CHEN Yu-Cheng; XIONG Zhi-Ting; DONG Shan-Yan

    2006-01-01

    A soil batch experiment was conducted to investigate both separate and compound effects of three types of surfactants:anionic dodecylbenzene sulfonic acid sodiumsalt (DBSS), cationic cetyltrimethylammonium bromide (CTAB), and nonionic nonyl phenol polyethyleneoxy ether (TX-100), as well as ethylenediaminetetraacetic acid (EDTA) on cadmium solubility, sorption kinetics, and sorption-desorption behavior in purple soil. The results indicated that both individual application of the three types of surfactants and surfactants combined with EDTA could stimulate Cd extraction from the soil with a general effectiveness ranking of EDTA/TX-100 > EDTA/DBSS > EDTA/CTAB > EDTA > TX-100 >DBSS > CTAB. Further study showed that the compound application of surfactants and EDTA had stronger (P < 0.05)effects on Cd solubility than those added individually. The application of surfactants and EDTA to purple soil (P < 0.05)decreased the proportion of Cd sorbed, while their effectiveness ranking was similar to that of enhanced solubilization. The sorption kinetics of Cd in purple soil was best described by the double-constant equation, while the Freundlich equation gave an excellent fit to the sorption isotherm curves. Therefore, surfactant-enhanced remediation of Cd contaminated soil is feasible and further research should be conducted.

  13. Surfactant mediated self-assembly of weakly charged polymer on hydrophobic polymeric substrate

    Science.gov (United States)

    Goswami, Monojoy; Sumpter, Bobby

    2011-03-01

    Molecular Dynamics (MD) simulations are carried out to understand the physical aspects of different bulk morphologies formed in charged diblock copolymers. It has been seen that the bulk morphologies formed by charged block copolymers, 75 vol % fluorinated polyisoprene (FPI) - 25 vol% sulfonated polystyrene (PSS) with 50% sulfonation are substantially different from their diblock counterparts. In this study we show how the bulk morphologies change from the uncharged diblock counterparts and also how morphology can be tuned with volume fraction of the charged block and with a change in dielectric constant. A physical understanding based on the underlying strong electrostatic interactions between the charged block and counterions is obtained. The 75/25 diblock shows hexagonal morphologies with the minority blocks (PSS) forming the continuous phase due to charge percolation and the FPI blocks arranged in hexagonal cylinders. Some long-range order can be sustained even by changing the dielectric of the medium. Diverse and atypical morphologies are readily accessible by simply changing the number distribution of the charges on PSS block.

  14. Mixtures of latex particles and the surfactant of opposite charge used as interface stabilizers--influence of particle contact angle, zeta potential, flocculation and shear energy.

    Science.gov (United States)

    Deleurence, Rémi; Parneix, Caroline; Monteux, Cécile

    2014-09-28

    We investigate the stabilization of air-water interfaces by mixtures of negatively charged latex particles (sulfate polystyrene) and cationic surfactants (alkyl trimethylammonium bromides). First we report results concerning the binding of surfactant molecules to the latex particles. As the surfactant concentration increases, the charge of the particles reverses, from negative to positive, because CnTAB first binds electrostatically to the latex particles and then through hydrophobic interaction with the monolayer already adsorbed on the particles as well as directly with the hydrophobic surface of the latex. Over a large range of surfactant concentrations around the charge inversion, a strong flocculation is observed and 100 μm large aggregates form in the suspension. Unlike previous studies published on mixtures of inorganic particles with oppositely charged surfactants, we show that we can vary the sign of the zeta potential of the particles without changing the contact angle of the particles over a large range of surfactant concentrations. Indeed, the latex particles that we study are more hydrophobic than inorganic particles, hence adding moderate concentrations of the surfactant results in a weak variation of the contact angle while the charge of the particles can be reversed. This enables decoupling of the effect of zeta potential and contact angle on the interfacial properties of the mixtures. Our study shows that the contact angle and the charge of the particles are not sufficient parameters to control the foam properties, and the key-parameters are the flocculation state and the shear energy applied to produce the foam. Indeed, flocculated samples, whatever the sign of the zeta potential, enable production of a stable armour at the interface. The large aggregates do not adsorb spontaneously at the interface because of their large size, however when a large shear energy is used to produce the foam very stable foam is obtained, where particles are trapped

  15. The dynamic response of a fungal lipase in the presence of charged surfactants

    DEFF Research Database (Denmark)

    Peters, Günther H.J.

    2002-01-01

    Lipases are efficient catalysts for lipolytic reactions and require a lipid interface for optimal activity. To study the effect of small charged lipid aggregates on the behavior of these enzymes, we have performed molecular dynamics simulations on five different systems. The simulations carried o...

  16. Net charge affects morphology and visual properties of ovalbumin aggregates

    NARCIS (Netherlands)

    Weijers, M.; Broersen, K.; Barneveld, P.A.; Cohen Stuart, M.A.; Hamer, R.J.; Jongh, H.H.J.de; Visschers, R.W.

    2008-01-01

    The effect of ovalbumin net charge on aggregate morphology and visual properties was investigated using chromatography, electrophoresis, electron microscopy, and turbidity measurements. A range of differently charged ovalbumin variants (net charge ranging from -1 to -26 at pH 7) was produced using c

  17. Factors Affecting the Stability of Crude and Transmission Oil Emulsion Swith Surfactant Solutions

    Directory of Open Access Journals (Sweden)

    Erich Martínez Martín

    2016-04-01

    Full Text Available Crude oil emulsions with surfactant solutions are used to transport this for piping systems. The applicationof this technique requires that the emulsions remain stable during the pumping period and haveseparated after transporting the crude. In this paper, experimental assays were performed using differentconcentrations of surfactant, and mixing types settling conditions. They were employed as the continuousphase two substances: oil transmission and Cuban crude oil. The strong infl uence of the concentrationand type of mixing on the stability of the emulsions was observed. The results demonstrate the similaritiesin thermalhydraulic fl uid parameters objects of study. Allowing infer the approximate behavior of theCuban crude oil from experimental work with transmission oil.

  18. Space charges can significantly affect the dynamics of accelerator maps

    Science.gov (United States)

    Bountis, Tassos; Skokos, Charalampos

    2006-10-01

    Space charge effects can be very important for the dynamics of intense particle beams, as they repeatedly pass through nonlinear focusing elements, aiming to maximize the beam's luminosity properties in the storage rings of a high energy accelerator. In the case of hadron beams, whose charge distribution can be considered as “frozen” within a cylindrical core of small radius compared to the beam's dynamical aperture, analytical formulas have been recently derived [C. Benedetti, G. Turchetti, Phys. Lett. A 340 (2005) 461] for the contribution of space charges within first order Hamiltonian perturbation theory. These formulas involve distribution functions which, in general, do not lead to expressions that can be evaluated in closed form. In this Letter, we apply this theory to an example of a charge distribution, whose effect on the dynamics can be derived explicitly and in closed form, both in the case of 2-dimensional as well as 4-dimensional mapping models of hadron beams. We find that, even for very small values of the “perveance” (strength of the space charge effect) the long term stability of the dynamics changes considerably. In the flat beam case, the outer invariant “tori” surrounding the origin disappear, decreasing the size of the beam's dynamical aperture, while beyond a certain threshold the beam is almost entirely lost. Analogous results in mapping models of beams with 2-dimensional cross section demonstrate that in that case also, even for weak tune depressions, orbital diffusion is enhanced and many particles whose motion was bounded now escape to infinity, indicating that space charges can impose significant limitations on the beam's luminosity.

  19. Space charges can significantly affect the dynamics of accelerator maps

    Energy Technology Data Exchange (ETDEWEB)

    Bountis, Tassos [Department of Mathematics, University of Patras, GR-26500 Patras (Greece) and Center for Research and Applications of Nonlinear Systems (CRANS), University of Patras, GR-26500 Patras (Greece)]. E-mail: tassos50@otenet.gr; Skokos, Charalampos [Center for Research and Applications of Nonlinear Systems (CRANS), University of Patras, GR-26500 Patras (Greece)

    2006-10-09

    Space charge effects can be very important for the dynamics of intense particle beams, as they repeatedly pass through nonlinear focusing elements, aiming to maximize the beam's luminosity properties in the storage rings of a high energy accelerator. In the case of hadron beams, whose charge distribution can be considered as 'frozen' within a cylindrical core of small radius compared to the beam's dynamical aperture, analytical formulas have been recently derived [C. Benedetti, G. Turchetti, Phys. Lett. A 340 (2005) 461] for the contribution of space charges within first order Hamiltonian perturbation theory. These formulas involve distribution functions which, in general, do not lead to expressions that can be evaluated in closed form. In this Letter, we apply this theory to an example of a charge distribution, whose effect on the dynamics can be derived explicitly and in closed form, both in the case of 2-dimensional as well as 4-dimensional mapping models of hadron beams. We find that, even for very small values of the 'perveance' (strength of the space charge effect) the long term stability of the dynamics changes considerably. In the flat beam case, the outer invariant 'tori' surrounding the origin disappear, decreasing the size of the beam's dynamical aperture, while beyond a certain threshold the beam is almost entirely lost. Analogous results in mapping models of beams with 2-dimensional cross section demonstrate that in that case also, even for weak tune depressions, orbital diffusion is enhanced and many particles whose motion was bounded now escape to infinity, indicating that space charges can impose significant limitations on the beam's luminosity.

  20. Micellization properties of cardanol as a renewable co-surfactant.

    Science.gov (United States)

    Fontana, Antonella; Guernelli, Susanna; Zaccheroni, Nelsi; Zappacosta, Romina; Genovese, Damiano; De Crescentini, Lucia; Riela, Serena

    2015-09-21

    With the aim to improve the features of surfactant solutions in terms of sustainability and renewability we propose the use of hydrogenated natural and sustainable plant-derived cardanol as an additive to commercial surfactants. In the present study we demonstrated that its addition, in amounts as high as 10%, to commercial surfactants of different charge does not significantly affect surfactant properties. Conversely, the presence of hydrogenated cardanol can strongly affect spectrophotometric determination of CMC if preferential interactions with the dyes used take place. This latter evidence may be profitably exploited in surfactant manufacturing by considering that the concurrent presence of a rigid organic molecule such as Orange OT and 10% hydrogenated cardanol decreases the CMC of CTAB up to 65 times.

  1. Factors affecting the design of slow release formulations of herbicides based on clay-surfactant systems. A methodological approach.

    Directory of Open Access Journals (Sweden)

    María Del Carmen Galán-Jiménez

    Full Text Available A search for clay-surfactant based formulations with high percentage of the active ingredient, which can yield slow release of active molecules is described. The active ingredients were the herbicides metribuzin (MZ, mesotrione (MS and flurtamone (FL, whose solubilities were examined in the presence of four commercial surfactants; (i neutral: two berols (B048, B266 and an alkylpolyglucoside (AG6202; (ii cationic: an ethoxylated amine (ET/15. Significant percent of active ingredient (a.i. in the clay/surfactant/herbicide formulations could be achieved only when most of the surfactant was added as micelles. MZ and FL were well solubilized by berols, whereas MS by ET/15. Sorption of surfactants on the clay mineral sepiolite occurred mostly by sorption of micelles, and the loadings exceeded the CEC. Higher loadings were determined for B266 and ET/15. The sorption of surfactants was modeled by using the Langmuir-Scatchard equation which permitted the determination of binding coefficients that could be used for further predictions of the sorbed amounts of surfactants under a wide range of clay/surfactant ratios. A possibility was tested of designing clay-surfactant based formulations of certain herbicides by assuming the same ratio between herbicides and surfactants in the formulations as for herbicides incorporated in micelles in solution. Calculations indicated that satisfactory FL formulations could not be synthesized. The experimental fractions of herbicides in the formulations were in agreement with the predicted ones for MS and MZ. The validity of this approach was confirmed in in vitro release tests that showed a slowing down of the release of a.i. from the designed formulations relative to the technical products. Soil dissipation studies with MS formulations also showed improved bioactivity of the clay-surfactant formulation relative to the commercial one. This methodological approach can be extended to other clay-surfactant systems for

  2. Adsorption of surfactants and polymers at interfaces

    Science.gov (United States)

    Rojas, Orlando Jose

    Surface tension and high-resolution laser light scattering experiments were used to investigate the adsorption of isomeric sugar-based surfactants at the air/liquid interface in terms of surfactant surface packing and rheology. Soluble monolayers of submicellar surfactant solutions exhibited a relatively viscous behavior. It was also proved that light scattering of high-frequency thermally-induced capillary waves can be utilized to study surfactant exchange between the surface and the bulk solution. Such analysis revealed the existence of a diffusional relaxation mechanism. A procedure based on XPS was developed for quantification, on an absolute basis, of polymer adsorption on mica and Langmuir-Blodgett cellulose films. The adsorption of cationic polyelectrolytes on negatively-charged solid surfaces was highly dependent on the polymer ionicity. It was found that the adsorption process is driven by electrostatic mechanisms. Charge overcompensation (or charge reversal) of mica occurred after adsorption of polyelectrolytes of ca. 50% charge density, or higher. It was demonstrated that low-charge-density polyelectrolytes adsorb on solid surfaces with an extended configuration dominated by loops and tails. In this case the extent of adsorption is limited by steric constraints. The conformation of the polyelectrolyte in the adsorbed layer is dramatically affected by the presence of salts or surfactants in aqueous solution. The phenomena which occur upon increasing the ionic strength are consistent with the screening of the electrostatic attraction between polyelectrolyte segments and solid surface. This situation leads to polyelectrolyte desorption accompanied by both an increase in the layer thickness and the range of the steric force. Adsorbed polyelectrolytes and oppositely charged surfactants readily associate at the solid/liquid interface. Such association induces polyelectrolyte desorption at a surfactant concentration which depends on the polyelectrolyte charge

  3. Factors affecting protein transfer into surfactant-isooctane solution: a case study of extraction behavior of chemically modified cytochrome c.

    Science.gov (United States)

    Ono, T; Goto, M

    1998-01-01

    The extraction mechanism of proteins by surfactant molecules in an organic solvent has been investigated using a chemically modified protein. We conducted guanidylation on lysine residues of cytochrome c by replacing their amino groups with homoarginine to enhance the protein-surfactant interaction. Results have shown that guanidylated cytochrome c readily forms a hydrophobic complex with dioleyl phosphoric acid (DOLPA) through hydrogen bonding between the phosphate moiety and the guanidinium groups. Although improved protein-surfactant interaction activated the formation of a hydrophobic complex at the interface, it could not improve the protein transfer in isooctane. It has been established that the protein extraction mechanism using surfactant molecules is mainly governed by two processes: formation of an interfacial complex at the oil-water interface and the subsequent solubilization of the complex into the organic phase. In addition, a kinetic study demonstrated that guanidylation of lysine accelerated the initial extraction rate of cytochrome c. This fact implies that the protein transferability from aqueous phase into organic phase depends on the protein-surfactant interaction which can be modified by protein surface engineering.

  4. A review of factors affecting electrostatic charging of pharmaceuticals and adhesive mixtures for inhalation.

    Science.gov (United States)

    Kaialy, Waseem

    2016-04-30

    Pharmaceutical powders are typically insulators consisting of relatively small particles and thus they usually exhibit significant electrostatic charging behaviours. In the inhalation field, the measurement of electrostatic charge is an imperative stage during pharmaceutical formulation development. The electrostatic charge is affected by the interplay of many factors. This article reviews the factors affecting the electrostatic charging of pharmaceutical powders with a focus on dry powder inhalations. The influences of particle resistivity, size distribution, shape distribution, surface roughness, polymorphic form and hygroscopicity, as well as the effects of moisture uptake, environmental conditions, pharmaceutical processing (i.e., milling, sieving, spray drying and blending), and storage on the electrostatic charge behaviours of pharmaceuticals, with focus on inhalation powders, were reviewed. The influence of electrostatic charge on the performance of dry powder inhaler formulations in terms of drug content homogeneity, the passage of drug through the inhaler device, drug-carrier adhesion/detachment, and drug deposition on the respiratory airways were discussed. The understanding gained is crucial to improving the safety, quality, and efficiency of the pharmaceutical inhalation products.

  5. Desorption of organophosphorous pesticides from soil with wastewater and surfactant solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Soriano, M. C.; Mingorance, M. D.; Pena, A.

    2009-07-01

    Surfactants can be introduced in the environment by wastewater discharge, point-charge pollution or deliberate action, e. g. to remediate contaminated soil or groundwater. The irrigation of soil with wastewater containing surfactants may modify pesticide desorption from soil, thus affecting their affecting their environmental fate. Desorption from soil of the plain of Granada (South-eastern Spain) of two organophosphorous pesticides, diazinon and dimethoate, differing in solubility and hydrophobicity, has been evaluated in the presence of different surfactant aqueous solutions and municipal wastewater. (Author)

  6. Nanoparticles of Block Ionomer Complexes from Double Hydrophilic Poly(acrylic acid-b-poly(ethylene oxide-b-poly(acrylic acid Triblock Copolymer and Oppositely Charged Surfactant

    Directory of Open Access Journals (Sweden)

    Sun Yuelong

    2009-01-01

    Full Text Available Abstract The novel water-dispersible nanoparticles from the double hydrophilic poly(acrylic acid-b-poly(ethylene oxide-b-poly(acrylic acid (PAA-b-PEO-b-PAA triblock copolymer and oppositely charged surfactant dodecyltrimethyl ammonium bromide (DTAB were prepared by mixing the individual aqueous solutions. The structure of the nanoparticles was investigated as a function of the degree of neutralization (DN by turbidimetry, dynamic light scattering (DSL,ζ-potential measurement, and atomic force microscope (AFM. The neutralization of the anionic PAA blocks with cationic DTAB accompanied with the hydrophobic interaction of alkyl tails of DTAB led to formation of core–shell nanoparticles with the core of the DTAB neutralized PAA blocks and the shell of the looped PEO blocks. The water-dispersible nanoparticles with negative ζ-potential were obtained over the DN range from 0.4 to 2.0 and their sizes depended on the DN. The looped PEO blocks hindered the further neutralization of the PAA blocks with cationic DTAB, resulting in existence of some negative charged PAA-b-PEO-b-PAA backbones even when DN > 1.0. The spherical and ellipsoidal nature of these nanoparticles was observed with AFM.

  7. NOS2 is critical to the development of emphysema in Sftpd deficient mice but does not affect surfactant homeostasis.

    Directory of Open Access Journals (Sweden)

    Lars Knudsen

    Full Text Available RATIONALE: Surfactant protein D (SP-D has important immuno-modulatory properties. The absence of SP-D results in an inducible NO synthase (iNOS, coded by NOS2 gene related chronic inflammation, development of emphysema-like pathophysiology and alterations of surfactant homeostasis. OBJECTIVE: In order to test the hypothesis that SP-D deficiency related abnormalities in pulmonary structure and function are a consequence of iNOS induced inflammation, we generated SP-D and iNOS double knockout mice (DiNOS. METHODS: Structural data obtained by design-based stereology to quantify the emphysema-like phenotype and disturbances of the intracellular surfactant were correlated to invasive pulmonary function tests and inflammatory markers including activation markers of alveolar macrophages and compared to SP-D (Sftpd(-/- and iNOS single knockout mice (NOS2(-/- as well as wild type (WT littermates. MEASUREMENTS AND RESULTS: DiNOS mice had reduced inflammatory cells in BAL and BAL-derived alveolar macrophages showed an increased expression of markers of an alternative activation as well as reduced inflammation. As evidenced by increased alveolar numbers and surface area, emphysematous changes were attenuated in DiNOS while disturbances of the surfactant system remained virtually unchanged. Sftpd(-/- demonstrated alterations of intrinsic mechanical properties of lung parenchyma as shown by reduced stiffness and resistance at its static limits, which could be corrected by additional ablation of NOS2 gene in DiNOS. CONCLUSION: iNOS related inflammation in the absence of SP-D is involved in the emphysematous remodeling leading to a loss of alveoli and associated alterations of elastic properties of lung parenchyma while disturbances of surfactant homeostasis are mediated by different mechanisms.

  8. 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 cati

  9. pH-Sensitive surfactants from lysine: assessment of their cytotoxicity and environmental behavior.

    Science.gov (United States)

    Colomer, Aurora; Pinazo, Aurora; García, Maria Teresa; Mitjans, Montserrat; Vinardell, M Pilar; Infante, Maria Rosa; Martínez, Verónica; Pérez, Lourdes

    2012-04-10

    The toxicity and environmental behavior of new pH-sensitive surfactants from lysine are presented. Three different chemical structures are studied: surfactants with one amino acid and one alkyl chain, surfactants with two amino acids on the polar head and one alkyl chain, and gemini surfactants. The pH sensitivity of these compounds can be tuned by modifying their chemical structures. Cytotoxicity has been evaluated using erythrocytes and fibroblast cells. The toxic effects against these cells depend on the hydrophobicity of the molecules as well as their cationic charge density. The effect of hydrophobicity and cationic charge density on toxicity is different for each type of cells. For erythrocytes, the toxicity increases as hydrophobicity and charge density increases. Nevertheless, for fibroblasts cationic charge density affects cytotoxicity in the opposite way: the higher charge density, the lower the toxicity. The effect of the pH on hemolysis has been evaluated in detail. The aquatic toxicity was established using Daphnia magna . All surfactants yielded EC(50) values considerably higher than that reported for cationic surfactants based on quaternary ammonium groups. Finally, their biodegradability was evaluated using the CO(2) headspace test (ISO 14593). These lysine derivatives showed high levels of biodegradation under aerobic conditions and can be classified as "readily biodegradable compounds".

  10. Desorption of organo phosphorous pesticides from soil with wastewater and surfactant solution

    OpenAIRE

    Hernandez-Soriano, Maria del Carmen; Mingorance, Maria Dolores; Peña, Aranzazu

    2008-01-01

    Surfactants can be introduced in the environment by wastewater discharge, point-charge pollution or deliberate action, e.g. to remediate contaminated soil or groundwater. The irrigation of soil with wastewater containing surfactants may modify pesticide desorption from soil, thus affecting their environmental fate. Desorption from soil of the plain of Granada (South-eastern Spain) of two organophosphorous pesticides, diazinon and dimethoate, differing in solubility and hydrophobicity...

  11. Exploration of twisted intramolecular charge transfer fluorescence properties of trans-2-[4-(dimethylamino)styryl]benzothiazole to characterize the protein-surfactant aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Muthusubramanian, Sowmiya [Department of Chemistry, Birla Institute of Technology and Science, Pilani 333031, Rajasthan (India); Saha, Subit Kumar, E-mail: sksaha@bits-pilani.ac.in [Department of Chemistry, Birla Institute of Technology and Science, Pilani 333031, Rajasthan (India)

    2012-08-15

    The characterization of aggregates of an anionic surfactant, sodium dodecyl sulphate (SDS) with bovine serum albumin (BSA) in various regions of binding isotherm of SDS to BSA with increasing concentration of the former have been done by exploring the twisted intramolecular charge transfer (TICT) fluorescence properties of a probe, trans-2-[4-(dimethylamino)styryl] benzothiazole (DMASBT). The TICT fluorescence, steady-state fluorescence anisotropy and time-resolved fluorescence of DMASBT, and the fluorescence resonance energy transfer (FRET) study reveal the characteristics of the native protein as well as the protein-surfactant aggregates viz., micropolarity, microviscosity, locations of probe, denaturation of protein in various regions of binding isotherm, and also the validation of necklace-bead model. The changes in the polarity and the viscosity of the microenvironment around the probe from one binding region of SDS to other have been reflected in the highly sensitive fluorescence properties of DMASBT. The study of FRET between the DMASBT and the tryptophan residue (Trp) of BSA has identified the locations of the probe molecule in the native protein as well as that in various BSA-SDS aggregates. The energy transfer efficiency decreases, whereas the distance between the DMASBT and the Trp residue increases with increasing concentration of SDS. The significant change in the conformations of protein molecules during the non-cooperative binding region of SDS is evidenced by the fluorescence anisotropic behavior of DMASBT in the same region. - Highlights: Black-Right-Pointing-Pointer Micropolarity and microviscosity of environment around the probe in BSA-SDS aggregates is reported. Black-Right-Pointing-Pointer Denaturation of protein is demonstrated by the TCSPC of DMASBT and FRET study. Black-Right-Pointing-Pointer Location of the probe in the native protein and BSA-SDS aggregates is identified using FRET study. Black-Right-Pointing-Pointer During unfolding of BSA

  12. A spectroscopic study of factors affecting charge transfer at organo-metallic interfaces

    CERN Document Server

    Tucker, C E

    2001-01-01

    polydiacetylene and omega-tricosenoic acid LB films. The resulting analyses have allowed comparison of charge trapping within the different bulk films and also at the film to substrate interface. In addition to DBARS, Fourier Transform Infra-red (FTIR) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopies have been used to investigate the factors affecting the carboxylic acid group at the head of the LB molecule and the role this plays in charge transport across the organo-metallic boundary. The properties of organic films produced by the Langmuir-Blodgett (LB) technique have become more widely known in the last few decades, as the variety of organic molecules suitable for this method of production has increased. One class of LB molecule receiving particular attention has been that of conjugated polymers. These organic materials exhibit an anisotropic semi-conductor like behavior along the polymer chain, making them suitable candidate materials for use in molecular electronic devices. However,...

  13. Effects of Concentration and Conformation of Surfactants on Phase Separation of Surfactant-Water-Oil Systems

    Institute of Scientific and Technical Information of China (English)

    袁银权; 邹宪武; 刘昊阳

    2004-01-01

    The effects of surfactants on the phase separation of surfactant-water-oil systems have been investigated by using discontinuous molecular dynamic simulations. The phase separation speed and equilibrium configuration are dependent on the surfactant concentration and conformation. The equilibrium concentration of surfactants at the interface remains constant. With the increasing surfactant concentration, the equilibrium configuration crosses over from the disperse phase to the bicontinuous one. The crossover concentration is estimated. The conformation of the surfactant has little effect on the equilibrium concentration of surfactants at the interface,while it affects the equilibrium configuration after phase separation.

  14. Surfactant for pediatric acute lung injury.

    Science.gov (United States)

    Willson, Douglas F; Chess, Patricia R; Notter, Robert H

    2008-06-01

    This article reviews exogenous surfactant therapy and its use in mitigating acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) in infants, children, and adults. Biophysical and animal research documenting surfactant dysfunction in ALI/ARDS is described, and the scientific rationale for treatment with exogenous surfactant is discussed. Major emphasis is placed on reviewing clinical studies of surfactant therapy in pediatric and adult patients who have ALI/ARDS. Particular advantages from surfactant therapy in direct pulmonary forms of these syndromes are described. Also discussed are additional factors affecting the efficacy of exogenous surfactants in ALI/ARDS.

  15. 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.

  16. 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.

  17. Surfactant enhanced volumetric sweep efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Harwell, J.H.; Scamehorn, J.F.

    1989-10-01

    Surfactant-enhanced waterflooding is a novel EOR method aimed to improve the volumetric sweep efficiencies in reservoirs. The technique depends upon the ability to induce phase changes in surfactant solutions by mixing with surfactants of opposite charge or with salts of appropriate type. One surfactant or salt solution is injected into the reservoir. It is followed later by injection of another surfactant or salt solution. The sequence of injections is arranged so that the two solutions do not mix until they are into the permeable regions well away from the well bore. When they mix at this point, by design they form a precipitate or gel-like coacervate phase, plugging this permeable region, forcing flow through less permeable regions of the reservoir, improving sweep efficiency. The selectivity of the plugging process is demonstrated by achieving permeability reductions in the high permeable regions of Berea sandstone cores. Strategies were set to obtain a better control over the plug placement and the stability of plugs. A numerical simulator has been developed to investigate the potential increases in oil production of model systems. Furthermore, the hardness tolerance of anionic surfactant solutions is shown to be enhanced by addition of monovalent electrolyte or nonionic surfactants. 34 refs., 32 figs., 8 tabs.

  18. Kolliphor surfactants affect solubilization and bioavailability of fenofibrate. Studies of in vitro digestion and absorption in rats

    DEFF Research Database (Denmark)

    Berthelsen, Ragna; Holm, Rene; Jacobsen, Jette;

    2015-01-01

    Selection of excipients for drug formulations requires both intellectual and experimental considerations as many of the used excipients are affected by physiological factors, e.g., they may be digested by pancreatic enzymes in the gastrointestinal tract. In the present paper we have looked...

  19. A Review on Progress in QSPR Studies for Surfactants

    Directory of Open Access Journals (Sweden)

    Zhengwu Wang

    2010-03-01

    Full Text Available 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 on cloud point (for nonionic surfactants, biodegradation potential and some other properties of surfactants are evaluated .

  20. Electrokinetic investigation of surfactant adsorption.

    Science.gov (United States)

    Bellmann, C; Synytska, A; Caspari, A; Drechsler, A; Grundke, K

    2007-05-15

    Fuerstenau [D.W. Fuerstenau, in: M.L. Hair (Ed.), Dekker, New York, 1971, p. 143] has already discussed the role of hydrocarbon chain of surfactants, the effect of alkyl chain length, chain structure and the pH of the solution on the adsorption process of surfactants. Later Kosmulski [M. Kosmulski, Chemical Properties of Material Surfaces, Surfactant Science Series, vol. 102, Dekker, New York, Basel, 2001] included the effect of surfactant concentration, equilibration time, temperature and electrolyte in his approaches. Certainly, the character of the head groups of the surfactant and the properties of the adsorbent surface are the basis for the adsorption process. Different surfactants and adsorbents cause different adsorption mechanisms described firstly by Rosen [M.J. Rosen, Surfactants and Interfacial Phenomena, second ed., Wiley, New York, 1989]. These adsorption mechanisms and their influencing factors were studied by electrokinetic investigations. Here only changes of the charges at the surfaces could be detected. To control the results of electrokinetic investigations they were compared with results from ellipsometric measurements. In the case of surfactant adsorption the chain length was vitally important. It could be shown by the adsorption of alkyl trimethyl ammonium bromides onto polymer films spin coated at wafer surfaces. The influence of the chain length depending on surface properties of the polymer film was studied. Streaming potential measurements were applied for these investigations. The obtained results enabled us to calculate the molar cohesive free energy per mol of CH2-group in the alkaline chain of the surfactant if all other specific adsorption effects were neglected.

  1. 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...

  2. Tuning Polyelectrolyte-Surfactant Interactions: Modification of Poly(ethylenimine) with Propylene Oxide and Blocks of Ethylene Oxide.

    Science.gov (United States)

    Penfold, J; Thomas, R K; Li, P; Batchelor, S N; Tucker, I M; Burley, A W

    2016-02-02

    Significantly enhanced adsorption at the air-water interface arises in polyelectrolyte/ionic surfactant mixtures, such as poly(ethylenimine)/sodium dodecyl sulfate (PEI/SDS), down to relatively low surfactant concentrations due to a strong surface interaction between the polyelectrolyte and surfactant. In the region of charge neutralization this can result in precipitation or coacervation and give rise to undesirable properties in many applications. Ethoxylation of the PEI can avoid precipitation, but can also considerably weaken the interaction. Localization of the ethoxylation can overcome these shortcomings. Further manipulation of the polyelectrolyte-surfactant interaction can be achieved by selective ethoxylation and propoxylation of the PEI amine groups. Neutron reflectivity and surface tension data are presented here which show how the polyelectrolyte-surfactant interaction can be manipulated by tuning the PEI structure. Using deuterium labeled surfactant and polymer the neutron reflectivity measurements provide details of the surface composition and structure of the adsorbed layer. The general pattern of behavior is that at low surfactant concentrations there is enhanced surfactant adsorption due to the strong surface interaction; whereas around the region of the SDS critical micellar concentration, cmc, the surface is partially depleted of surfactant in favor bulk aggregate structures. The results presented here show how these characteristic features of the adsorption are affected by the degree of ethoxylation and propoxylation. Increasing the degree of propoxylation enhances the surfactant adsorption, whereas varying the degree of ethoxylation has a less pronounced effect. In the region of surfactant surface depletion increasing both the degree of ethoxylation and propoxylation result in an increased surface depletion.

  3. Synthesis of high quality MCM-48 with binary cationic-nonionic surfactants.

    Science.gov (United States)

    Zhao, Wei; Li, Quanzhi; Wang, Lina; Chu, Jinglong; Qu, Jinkui; Li, Shaohua; Qi, Tao

    2010-05-18

    Highly ordered MCM-48 was synthesized in the hydrothermal system of a mixture of cationic cetyltrimethylammonium bromide (CTAB) and nonionic poly(ethylene glycol) monooctylphenyl ether (Tx-100) using water glass as the silicon source. The effect of various factors, such as the amount of surfactant, CTAB/Tx-100, Si source, crystallization temperature, and crystallization time, on the synthesis were discussed in detail. The local effective surfactant packing parameter theory and the charge balance theory were used to explain the reason that various factors can affect the product structure reasonably. Especially, the role of Tx-100 was expounded. The optimum synthesis conditions for MCM-48 were obtained.

  4. Derivation of original RESP atomic partial charges for MD simulations of the LDAO surfactant with AMBER: applications to a model of micelle and a fragment of the lipid kinase PI4KA.

    Science.gov (United States)

    Karakas, Esra; Taveneau, Cyntia; Bressanelli, Stéphane; Marchi, Massimo; Robert, Bruno; Abel, Stéphane

    2017-01-01

    In this paper, we describe the derivation and the validation of original RESP atomic partial charges for the N, N-dimethyl-dodecylamine oxide (LDAO) surfactant. These charges, designed to be fully compatible with all the AMBER force fields, are at first tested against molecular dynamics simulations of pure LDAO micelles and with a fragment of the lipid kinase PIK4A (DI) modeled with the QUARK molecular modeling server. To model the micelle, we used two distinct AMBER force fields (i.e. Amber99SB and Lipid14) and a variety of starting conditions. We find that the micelle structural properties (such as the shape, size, the LDAO headgroup hydration, and alkyl chain conformation) slightly depend on the force field but not on the starting conditions and more importantly are in good agreement with experiments and previous simulations. We also show that the Lipid14 force field should be used instead of the Amber99SB one to better reproduce the C(sp3)C(sp3)C(sp3)C(sp3) conformation in the surfactant alkyl chain. Concerning the simulations with LDAO-DI protein, we carried out different runs at two NaCl concentrations (i.e. 0 and 300 mM) to mimic, in the latter case, the experimental conditions. We notice a small dependence of the simulation results with the LDAO parameters and the salt concentration. However, we find that in the simulations, three out of four tryptophans of the DI protein are not accessible to water in agreement with our fluorescence spectroscopy experiments reported in the paper.

  5. Joint influence of surfactants and humic matter on PAH solubility. Are mixed micelles formed?

    Energy Technology Data Exchange (ETDEWEB)

    Lippold, H.; Gottschalch, U.; Kupsch, H. [Inst. of Interdisziplinare Isotopeforschung, Leipzig (Germany)

    2008-02-15

    Mobilization of polycyclic aromatic hydrocarbons (PAH) by surfactants, present at contaminated sites or deliberately introduced for remediation purposes, is inevitably associated with the influence of humic substances, which are ubiquitous in natural systems. Therefore, the solubilizing effects of anthropogenic and natural amphiphiles must be considered in their combined action since synergistic or antagonistic effects may be expected, for instance, as a consequence of mixed micellization. In this paper, solubilization of {sup 14}C-labeled pyrene in single-component and mixed solutions of surfactants and humic acid (coal-derived) was investigated up to the micellar concentration range. At low concentrations, antagonistic effects were observed for systems with cationic as well as anionic surfactants. Solubility enhancements in the presence of humic acid were canceled on addition of a cationic surfactant (DTAB) since charge compensation at humic colloids entailed precipitation. Solubility was also found to be decreased in the presence of an anionic surfactant (SDS), which was attributed to a competitive effect in respect of pyrene-humic interaction. This explanation is based on octanol-water partitioning experiments with radiolabeled humic acid, yielding evidence of different interaction modes between humic colloids and cationic/anionic surfactants. At higher concentrations, the effects of humic acid and SIDS were found to be additive. Thus, a formation of mixed micelles is very unlikely, which was confirmed by size exclusion chromatography of mixed systems. It can be concluded that remediation measures on the basis of micellar solubilization are not significantly affected by the presence of natural amphiphilic compounds.

  6. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    CERN Document Server

    Voisin, D

    2002-01-01

    Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each po...

  7. Studies on the electrocapillary curves of anionic surfactants in presence of non-ionic surfactants.

    Science.gov (United States)

    Bembi, R; Goyal, R N; Malik, W U

    1976-09-01

    Polyoxyethylated non-ionic surfactants such as Tween 20, Tween 40, Nonidet P40 and Nonex 501 have been supposed to be associated with cationic characteristics. Studies on the effect of these surfactants on the electrocapillary curves of the anionic surfactants Aerosol IB, Manaxol OT and sodium lauryl sulphate (SLS), show that the electrocapillary maxima shift towards positive potentials. The order of adsorption of the anionic surfactants is SLS > Manaxol OT > Aerosol IB while the shift in maxima is in the order Aerosol IB ~ Manaxol OT > SLS which confirms association of cationic characteristics with the micelles of these non-ionic surfactants. The magnitude of the shift in electrocapillary maxima is Nonex 501 > Nonidet P40 > Tween 20 > Tween 40 which may be the order of magnitude of the positive charge carried by these non-ionic surfactants.

  8. Parameters affecting the transscleral delivery of two positively charged proteins of comparable size.

    Science.gov (United States)

    Grimaudo, Maria Aurora; Tratta, Elena; Pescina, Silvia; Padula, Cristina; Santi, Patrizia; Nicoli, Sara

    2017-02-20

    Apart from molecular weight and net surface charge, there are other macromolecule-related factors that could, in principle, influence their diffusion across biological tissues, such as shape, conformability, water solubility and surface charge distribution. Lysozyme and cytochrome c, proteins with comparable molecular weight, isoelectric point and net surface charge in physiological conditions (approx. +7.8), are suitable model compounds for comparative studies, in particular to find out if other properties can have a role in the permeation across the sclera. The comparison between lysozyme and cytochrome c permeability was conducted by studying the permeation across the sclera and the choroid-Bruch's membrane and the diffusion across a hyaluronan gel-matrix. Melanin binding tests and the measurement of the electroosmosis flow during transscleral iontophoresis allowed for the evaluation of macromolecules affinity for the ocular tissues. Finally, anodal iontophoresis was applied to further confirm the interaction of the two proteins with the sclera. The data here collected show that two proteins with very similar MW, p Ka and charge can display very different diffusion properties across biological barriers. In particular, these differences can be attributed to a different interaction with specific components of ocular tissues: while the interaction with melanin and collagen fibers is apparently the same for the two molecules, a relevant difference was found in case of hyaluronic acid. Considering also literature evidences, the important parameters that can be responsible for this different affinity are molecular shape (spherical for cytochrome c vs prolate for lysozyme) and a combination of hydrophobic and electrostatic interactions that depends on the surface charge distribution. The interactions between sclera components and lysozyme are relatively strong and were not altered by the application of electric current.

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

    Science.gov (United States)

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

    2015-06-20

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Switchable Pickering emulsions stabilized by silica nanoparticles hydrophobized in situ with a conventional cationic surfactant.

    Science.gov (United States)

    Zhu, Yue; Jiang, Jianzhong; Liu, Kaihong; Cui, Zhenggang; Binks, Bernard P

    2015-03-24

    A stable oil-in-water Pickering emulsion stabilized by negatively charged silica nanoparticles hydrophobized in situ with a trace amount of a conventional cationic surfactant can be rendered unstable on addition of an equimolar amount of an anionic surfactant. The emulsion can be subsequently restabilized by adding a similar trace amount of cationic surfactant along with rehomogenization. This destabilization-stabilization behavior can be cycled many times, demonstrating that the Pickering emulsion is switchable. The trigger is the stronger electrostatic interaction between the oppositely charged ionic surfactants compared with that between the cationic surfactant and the (initially) negatively charged particle surfaces. The cationic surfactant prefers to form ion pairs with the added anionic surfactant and thus desorbs from particle surfaces rendering them surface-inactive. This access to switchable Pickering emulsions is easier than those employing switchable surfactants, polymers, or surface-active particles, avoiding both the complicated synthesis and the stringent switching conditions.

  12. Dissolution of Aluminum in Variably Charged Soils as Affected by Low-Molecular-Weight Organic Acids

    Institute of Scientific and Technical Information of China (English)

    LI Jiu-Yu; XU Ren-Kou; JI Guo-Liang

    2005-01-01

    Low-molecular-weight (LMW) organic acids exist widely in soils and play an important role in soil processes such as mineral weathering, nutrient mobilization and Al detoxification. In this research, a batch experiment was conducted to examine the effects of LMW organic acids on dissolution of aluminum in two variably charged soils, an Ultisol and an Oxisol. The results showed that the LMW organic acids enhanced the dissolution of Al in the two investigated soils in the following order: citric > oxalic > malonic > malic > tartaric > salicylic > lactic > maleic. This was generally in agreement with the magnitude of the stability constants for the Al-organic complexes. The effects of LMW organic acids on Al dissolution were greater in the Ultisol than in the Oxisol as compared to their controls. Also, the accelerating effects of citric and oxalic acids on dissolution of Al increased with an increase in pH, while the effects of lactic and salicylic acids decreased. Additionally, when the organic acid concentration was less than 0.2 mmol L-1, the dissolution of Al changed little with increase in acid concentration. However, when the organic acid concentration was greater than 0.2 mmol L-1,the dissolution of Al increased with increase in acid concentration. In addition to the acid first dissociation constant and stability constant of Al-organic complexes, the promoting effects of LMW organic acids on dissolution of Al were also related to their sorption-desorption equilibrium in the soils.

  13. Thermally cleavable surfactants

    Science.gov (United States)

    McElhanon, James R.; Simmons, Blake A.; Zifer, Thomas; Jamison, Gregory M.; Loy, Douglas A.; Rahimian, Kamyar; Long, Timothy M.; Wheeler, David R.; Staiger, Chad L.

    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.

  14. Thermally cleavable surfactants

    Energy Technology Data Exchange (ETDEWEB)

    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)

    2009-09-29

    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.

  15. Thermally cleavable surfactants

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Predictive model of cationic surfactant binding to humic substances

    NARCIS (Netherlands)

    Ishiguro, M.; Koopal, L.K.

    2011-01-01

    The humic substances (HS) have a high reactivity with other components in the natural environment. An important factor for the reactivity of HS is their negative charge. Cationic surfactants bind strongly to HS by electrostatic and specific interaction. Therefore, a surfactant binding model is devel

  17. A study of surfactant-assisted waterflooding

    Energy Technology Data Exchange (ETDEWEB)

    Scamehorn, J F; Harwell, J H

    1990-09-01

    In surfactant-assisted waterflooding, a surfactant slug is injected into a reservoir, followed by a brine spacer, followed by second surfactant slug. The charge on the surfactant in the first slug has opposite sign to that in the second slug. When the two slugs mix in the reservoir, a precipitate or coacervate is formed which plugs the permeable region of the reservoir. Subsequently injected water or brine is forced through the low permeability region of the reservoir, increasing sweep efficiency of the waterflood, compared to a waterflood not using surfactants. In this part of the work, two major tasks are performed. First, core floods are performed with oil present to demonstrate the improvement in incremental oil production, as well as permeability modification. Second, a reservoir simulation model will be proposed to further delineate the optimum strategy for implementation of the surfactant-assisted waterflooding, as well as indicate the reservoir types for which it would be most effective. Surfactants utilized were sodium dodecyl sulfate and dodecyl pyridinium chloride. 44 refs., 17 figs., 3 tabs.

  18. Delivery and performance of surfactant replacement therapies to treat pulmonary disorders.

    Science.gov (United States)

    El-Gendy, Nashwa; Kaviratna, Anubhav; Berkland, Cory; Dhar, Prajnaparamita

    2013-08-01

    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.

  19. Charge and geometry of residues in the loop 2 β hairpin differentially affect agonist and ethanol sensitivity in glycine receptors.

    Science.gov (United States)

    Perkins, Daya I; Trudell, James R; Asatryan, Liana; Davies, Daryl L; Alkana, Ronald L

    2012-05-01

    Recent studies highlighted the importance of loop 2 of α1 glycine receptors (GlyRs) in the propagation of ligand-binding energy to the channel gate. Mutations that changed polarity at position 52 in the β hairpin of loop 2 significantly affected sensitivity to ethanol. The present study extends the investigation to charged residues. We found that substituting alanine with the negative glutamate at position 52 (A52E) significantly left-shifted the glycine concentration response curve and increased sensitivity to ethanol, whereas the negative aspartate substitution (A52D) significantly right-shifted the glycine EC₅₀ but did not affect ethanol sensitivity. It is noteworthy that the uncharged glutamine at position 52 (A52Q) caused only a small right shift of the glycine EC₅₀ while increasing ethanol sensitivity as much as A52E. In contrast, the shorter uncharged asparagine (A52N) caused the greatest right shift of glycine EC₅₀ and reduced ethanol sensitivity to half of wild type. Collectively, these findings suggest that charge interactions determined by the specific geometry of the amino acid at position 52 (e.g., the 1-Å chain length difference between aspartate and glutamate) play differential roles in receptor sensitivity to agonist and ethanol. We interpret these results in terms of a new homology model of GlyR based on a prokaryotic ion channel and propose that these mutations form salt bridges to residues across the β hairpin (A52E-R59 and A52N-D57). We hypothesize that these electrostatic interactions distort loop 2, thereby changing agonist activation and ethanol modulation. This knowledge will help to define the key physical-chemical parameters that cause the actions of ethanol in GlyRs.

  20. Influence of surfactants in forced dynamic dewetting.

    Science.gov (United States)

    Henrich, Franziska; Fell, Daniela; Truszkowska, Dorota; Weirich, Marcel; Anyfantakis, Manos; Nguyen, Thi-Huong; Wagner, Manfred; Auernhammer, Günter K; Butt, Hans-Jürgen

    2016-09-20

    In this work we show that the forced dynamic dewetting of surfactant solutions depends sensitively on the surfactant concentration. To measure this effect, a hydrophobic rotating cylinder was horizontally half immersed in aqueous surfactant solutions. Dynamic contact angles were measured optically by extrapolating the contour of the meniscus to the contact line. Anionic (sodium 1-decanesulfonate, S-1DeS), cationic (cetyl trimethylammonium bromide, CTAB) and nonionic surfactants (C4E1, C8E3 and C12E5) with critical micelle concentrations (CMCs) spanning four orders of magnitude were used. The receding contact angle in water decreased with increasing velocity. This decrease was strongly enhanced when adding surfactant, even at surfactant concentrations of 10% of the critical micelle concentration. Plots of the receding contact angle-versus-velocity almost superimpose when being plotted at the same relative concentration (concentration/CMC). Thus the rescaled concentration is the dominating property for dynamic dewetting. The charge of the surfactants did not play a role, thus excluding electrostatic effects. The change in contact angle can be interpreted by local surface tension gradients, i.e. Marangoni stresses, close to the three-phase contact line. The decrease of dynamic contact angles with velocity follows two regimes. Despite the existence of Marangoni stresses close to the contact line, for a dewetting velocity above 1-10 mm s(-1) the hydrodynamic theory is able to describe the experimental results for all surfactant concentrations. At slower velocities an additional steep decrease of the contact angle with velocity was observed. Particle tracking velocimetry showed that the flow profiles do not differ with and without surfactant on a scales >100 μm.

  1. Particle and substrate charge effects on colloidal self-assembly in a sessile drop.

    Science.gov (United States)

    Yan, Qingfeng; Gao, Li; Sharma, Vyom; Chiang, Yet-Ming; Wong, C C

    2008-10-21

    By direct video monitoring of dynamic colloidal self-assembly during solvent evaporation in a sessile drop, we investigated the effect of surface charge on the ordering of colloidal spheres. The in situ observations revealed that the interaction between charged colloidal spheres and substrates affects the mobility of colloidal spheres during convective self-assembly, playing an important role in the colloidal crystal growth process. Both ordered and disordered growth was observed depending on different chemical conditions mediated by surface charge and surfactant additions to the sessile drop system. These different self-assembly behaviors were explained by the Coulombic and hydrophobic interactions between surface-charged colloidal spheres and substrates.

  2. 荷电膜去除水中表面活性剂十二烷基苯磺酸钠研究%STUDY ON THE REMOVAL OF SURFACTANT SODIUM DODECYL BENZENE SULFONATE BY CHARGED MEMBRANE

    Institute of Scientific and Technical Information of China (English)

    张洁欣; 魏俊富; 张环

    2011-01-01

    采用自制等离子体改性聚砜荷电膜对表面活性剂十二烷基苯磺酸钠(SDBS)进行截留测试,通过改变溶液的初始SDBS质量浓度(40~400 mg· L-1)、操作压力(0.15~0.35 MPa),离子强度(NaCl质量浓度100~300 mg·L-1)以及pH(2~12)等影响因素,观察荷电膜对SDBS溶液的截留率以及通量的变化,分析作用机理.结果表明,静电斥力为主要作用力,同时伴有机械筛分作用.初始SDBS含量低时比高时截留效果好,SDBS初始质量浓度为40 mg· L-1时截留率可达85.68%;低离子强度时静电斥力发挥主要作用,截留率比高离子强度时高;压力越大,截留率越高;溶液pH接近中性时截留效果最好.%Surfactant sodium dodecyl benzene sulfonate solution was retained by the plasma modified polysulfone charged membrane. The rejection tests were at different factors including solution concentration, operating pressure (0.15~0.35 Mpa), ionic strength (concentration of NaCl 100~300 mg*L') and pH (2~12). The retention rate and flux of SDBS solution retained by charged membrane were observed. The mechanism of retention was analyzed. Experimental results revealed that electrostatic repulsion was the main force in the process. And size exclusion also existed. Solutions possessing low concentration showed better rejection effect than those having high concentration. When initial feed concentration was 40 mg'L', the retention rate could reach 85.68%. Electrostatic repulsion played an important role at low ionic strength. The retention rate at low ionic strength was higher than those at high ionic strength. The retention rate increased as the operating pressure presented high. And the rejection performed well when pH was close to neutral.

  3. Perylenediimide-surfactant complexes: thermotropic liquid-crystalline materials via ionic self-assembly.

    Science.gov (United States)

    Guan, Ying; Zakrevskyy, Yuriy; Stumpe, Joachim; Antonietti, Markus; Faul, Charl F J

    2003-04-07

    In this communication we present the facile preparation and characterisation of thermotropic liquid-crystalline materials from the ionic self-assembly of a charged perylenediimide derivative and oppositely charged surfactants.

  4. Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time

    Institute of Scientific and Technical Information of China (English)

    Jia-li SHENTU; Zhen-li HE; Xiao-e YANG; Ting-qiang LI

    2008-01-01

    Effects of cadmium (Cd) on microbial biomass, activity and community diversity were assessed in a representative variable charge soil (Typic Aquult) using an incubation study. Cadmium was added as Cd(NO3)2> to reach a concentration range of 0~16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil mi-crobial biomass was enhanced at low Cd levels (0.5~1 mg/kg), but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate (<0.7 mg/kg available Cd), but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading (<1 mg/kg), and enhanced at higher Cd levels. Soil microbial metabolic quotient (MMQ) was generally greater at high Cd loading (1~16 mg/kg). However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids (PLFAs) for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination.

  5. SP-A-enriched surfactant for treatment of rat lung transplants with SP-A deficiency after storage and reperfusion

    NARCIS (Netherlands)

    Erasmus, ME; Hofstede, GJH; Petersen, AH; Batenburg, JJ; Haagsman, HP; Oetomo, SB; Prop, J

    2002-01-01

    Background. The function of pulmonary surfactant is affected by lung transplantation, contributing to impaired lung transplant function. A decreased amount of surfactant protein-A (SP-A) after reperfusion is believed to contribute to the impaired surfactant function. Surfactant treatment has been sh

  6. 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

  7. Interaction of photosensitive surfactant with DNA and poly acrylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Zakrevskyy, Yuriy, E-mail: yuriy.zakrevskyy@fh-koeln.de; Paasche, Jens; Lomadze, Nino; Santer, Svetlana, E-mail: santer@uni-potsdam.de [Experimental Physics, Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam (Germany); Cywinski, Piotr; Cywinska, Magdalena; Reich, Oliver; Löhmannsröben, Hans-Gerd [Physical Chemistry, Institute of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam (Germany)

    2014-01-28

    In this paper, we investigate interactions and phase transitions in polyelectrolyte-surfactant complexes formed between a cationic azobenzene-containing surfactant and two types of polyelectrolytes: natural (DNA) or synthetic (PAA: poly acrylic acid). The construction of a phase diagram allowed distancing between four major phases: extended coil conformation, colloidally stable compacted globules, colloidal instability range, and surfactant-stabilized compact state. Investigation on the complexes’ properties in different phases and under irradiation with UV light provides information about the role of the surfactant's hydrophobic trans isomers both in the formation and destruction of DNA and PAA globules as well as in their colloidal stabilization. The trans isomer shows much stronger affinity to the polyelectrolytes than the hydrophilic cis counterpart. There is no need for complete compensation of the polyelectrolyte charges to reach the complete compaction. On contrary to the findings previously reported in the literature, we demonstrate – for the first time – complete polyelectrolyte compaction which occurs already at 20% of DNA (and at 50% of PAA) charge compensation. The trans isomer plays the main role in the compaction. The aggregation between azobenzene units in the photosensitive surfactant is a driving force of this process. The decompaction can be realized during UV light irradiation and is strongly influenced by the interplay between surfactant-surfactant and surfactant-DNA interactions in the compacted globules.

  8. Interaction of photosensitive surfactant with DNA and poly acrylic acid

    Science.gov (United States)

    Zakrevskyy, Yuriy; Cywinski, Piotr; Cywinska, Magdalena; Paasche, Jens; Lomadze, Nino; Reich, Oliver; Löhmannsröben, Hans-Gerd; Santer, Svetlana

    2014-01-01

    In this paper, we investigate interactions and phase transitions in polyelectrolyte-surfactant complexes formed between a cationic azobenzene-containing surfactant and two types of polyelectrolytes: natural (DNA) or synthetic (PAA: poly acrylic acid). The construction of a phase diagram allowed distancing between four major phases: extended coil conformation, colloidally stable compacted globules, colloidal instability range, and surfactant-stabilized compact state. Investigation on the complexes' properties in different phases and under irradiation with UV light provides information about the role of the surfactant's hydrophobic trans isomers both in the formation and destruction of DNA and PAA globules as well as in their colloidal stabilization. The trans isomer shows much stronger affinity to the polyelectrolytes than the hydrophilic cis counterpart. There is no need for complete compensation of the polyelectrolyte charges to reach the complete compaction. On contrary to the findings previously reported in the literature, we demonstrate - for the first time - complete polyelectrolyte compaction which occurs already at 20% of DNA (and at 50% of PAA) charge compensation. The trans isomer plays the main role in the compaction. The aggregation between azobenzene units in the photosensitive surfactant is a driving force of this process. The decompaction can be realized during UV light irradiation and is strongly influenced by the interplay between surfactant-surfactant and surfactant-DNA interactions in the compacted globules.

  9. POLYMERIC SURFACTANT STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    P.M. Saville; J.W. White

    2001-01-01

    Polymeric surfactants are amongst the most widespread of all polymers. In nature, proteins and polysaccharides cause self organization as a result of this surfactancy; in industry, polymeric surfactants play key roles in the food, explosives and surface coatings sectors. The generation of useful nano- and micro-structures in films and emulsions as a result of polymer amphiphilicity and the application of mechanical stress is discussed. The use of X-ray and neutron small angle scattering and reflectivity to measure these structures and their dynamic properties will be described. New results on linear and dendritic polymer surfactants are presented.

  10. Dendrimer-surfactant interactions.

    Science.gov (United States)

    Cheng, Yiyun; Zhao, Libo; Li, Tianfu

    2014-04-28

    In this article, we reviewed the interactions between dendrimers and surfactants with particular focus on the interaction mechanisms and physicochemical properties of the yielding dendrimer-surfactant aggregates. In order to provide insight into the behavior of dendrimers in biological systems, the interactions of dendrimers with bio-surfactants such as phospholipids in bulk solutions, in solid-supported bilayers and at the interface of phases or solid-states were discussed. Applications of the dendrimer-surfactant aggregates as templates to guide the synthesis of nanoparticles and in drug or gene delivery were also mentioned.

  11. Characterization and control of surfactant-mediated Norovirus interactions.

    Science.gov (United States)

    Mertens, Brittany S; Velev, Orlin D

    2015-11-28

    Understanding of the colloidal interactions of Norovirus particles in aqueous medium could provide insights on the origins of the notorious stability and infectivity of these widespread viral agents. We characterized the effects of solution pH and surfactant type and concentration on the aggregation, dispersion, and disassembly of Norovirus virus-like particles (VLPs) using dynamic light scattering, electrophoretic light scattering, and transmission electron microscopy. Owing to net negative surface charge of the VLPs at neutral pH, low concentrations of cationic surfactant tend to aggregate the VLPs, whereas low concentrations of anionic surfactant tend to disperse the particles. Increasing the concentration of these surfactants beyond their critical micelle concentration leads to virus capsid disassembly and breakdown of aggregates. Non-ionic surfactants, however, had little effect on virus interactions and likely stabilized them additionally in suspension. The data were interpreted on the basis of simple models for surfactant binding and re-charging of the virus capsid. We used zeta potential data to characterize virus surface charge and interpret the mechanisms behind these demonstrated surfactant-virus interactions. The fundamental understanding and control of these interactions will aid in practical formulations for virus inactivation and removal from contaminated surfaces.

  12. Surfactant Sector Needs Urgent Readjustment

    Institute of Scientific and Technical Information of China (English)

    Huang Hongzhou

    2007-01-01

    @@ Surfactant industrial system has been basically established After 50 years' development, China has already established a surfactant industrial system with a relatively complete product portfolio and can produce 4714 varieties of surfactants in cationic,anionic, nonionic and amphoteric categories.

  13. 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.

  14. SURFACTANTS IN LUBRICATION

    Science.gov (United States)

    Surfactants are one of the most widely applied materials by consumers and industry. The application areas for surfactants span from everyday mundane tasks such as cleaning, to highly complex processes involving the formulation of pharmaceuticals, foods, pesticides, lubricants, etc. Even though sur...

  15. Hot foam for weed control-Do alkyl polyglucoside surfactants used as foaming agents affect the mobility of organic contaminants in soil?

    Science.gov (United States)

    Cederlund, H; Börjesson, E

    2016-08-15

    Use of alkyl polyglucosides (APGs) as a foaming agent during hot water weed control may influence the environmental fate of organic contaminants in soil. We studied the effects of the APG-based foaming agent NCC Spuma (C8-C10) on leaching of diuron, glyphosate, and polycyclic aromatic hydrocarbons (PAHs) in sand columns. We also examined how APG concentration affected the apparent water solubility and adsorption of the herbicides and of the PAHs acenaphthene, acenaphthylene and fluorene. Application of APGs at the recommended concentration of 0.3% did not significantly affect leaching of any of the compounds studied. However, at a concentration of 1.5%, leaching of both diuron and glyphosate was significantly increased. The increased leaching corresponded to an increase in apparent water solubility of diuron and a decrease in glyphosate adsorption to the sand. However, APG addition did not significantly affect the mobility of PAHs even though their apparent water solubility was increased. These results suggest that application of APG-based foam during hot water weed control does not significantly affect the mobility of organic contaminants in soil if used according to recommendations. Moreover, they suggest that APGs could be useful for soil bioremediation purposes if higher concentrations are used.

  16. Phase diagrams of DNA-photosensitive surfactant complexes: effect of ionic strength and surfactant structure.

    Science.gov (United States)

    Zakrevskyy, Yuriy; Titov, Evgenii; Lomadze, Nino; Santer, Svetlana

    2014-10-28

    Realization of all-optically controlled and efficient DNA compaction is the major motivation in the study of interactions between DNA and photosensitive surfactants. In this article, using recently published approach of phase diagram construction [Y. Zakrevskyy, P. Cywinski, M. Cywinska, J. Paasche, N. Lomadze, O. Reich, H.-G. Löhmannsroben, and S. Santer, J. Chem. Phys. 140, 044907 (2014)], a strategy for substantial reduction of compaction agent concentration and simultaneous maintaining the light-induced decompaction efficiency is proposed. The role of ionic strength (NaCl concentration), as a very important environmental parameter, and surfactant structure (spacer length) on the changes of positions of phase transitions is investigated. Increase of ionic strength leads to increase of the surfactant concentration needed to compact DNA molecule. However, elongation of the spacer results to substantial reduction of this concentration. DNA compaction by surfactants with longer tails starts to take place in diluted solutions at charge ratios Z phase diagrams for different DNA-photosensitive surfactant systems allowed explanation and proposal of a strategy to overcome previously reported limitations of the light-induced decompaction for complexes with increasing surfactant hydrophobicity.

  17. Small-angle neutron scattering study of aggregate structures of multi-headed pyridinium surfactants in aqueous solution

    Indian Academy of Sciences (India)

    J Haldar; V K Aswal; P S Goyal; S Bhattacharya

    2004-08-01

    The aggregate structures of a set of novel single-chain surfactants bearing one, two and three pyridinium headgroups have been studied using small-angle neutron scattering (SANS). It is found that the nature of aggregate structures of these cationic surfactants depend on the number of headgroups present in the surfactants. The single-headed pyridinium surfactant forms the lamellar structure, whereas surfactants with double and triple headgroups form micelles in water. The aggregates shrink in size with increase in the number of headgroups in the surfactants. The aggregation number () continually decreases and the fractional charge () increases with more number of headgroups on the surfactants. The semimajor axis () and semiminor axis ( = ) of the micelle also decrease with the increase in the number of headgroups in the surfactants. This indicates that hydrocarbon chains in such micelles prepared from multiheaded surfactants adopt bent conformation and no longer stay in extended conformation.

  18. Effects of Surfactants on the Rate of Chemical Reactions

    Directory of Open Access Journals (Sweden)

    B. Samiey

    2014-01-01

    Full Text Available Surfactants are self-assembled compounds that depend on their structure and electric charge can interact as monomer or micelle with other compounds (substrates. These interactions which may catalyze or inhibit the reaction rates are studied with pseudophase, cooperativity, and stoichiometric (classical models. In this review, we discuss applying these models to study surfactant-substrate interactions and their effects on Diels-Alder, redox, photochemical, decomposition, enzymatic, isomerization, ligand exchange, radical, and nucleophilic reactions.

  19. Surface-enhanced Raman spectroscopy of surfactants on silver electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Soncheng; Birke, R.L.; Lombardi, J.R. (City Univ. of New York, NY (USA))

    1990-03-08

    Surface-enhanced Raman spectroscopy (SERS) has been used to study different kinds of surfactants (cationic, anionic, and nonionic surfactants) adsorbed on a roughened Ag electrode. Spectral assignments are made for the SERS spectrum of cetylpyridinium chloride (CPC), and it is shown that the molecule is oriented with its pyridinium ring end-on at the electrode surface at potentials positive to the point of zero charge (pzc) on Ag.

  20. Tuning of protein-surfactant interaction to modify the resultant structure.

    Science.gov (United States)

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

    2015-09-01

    Small-angle neutron scattering and dynamic light scattering studies have been carried out to examine the interaction of bovine serum albumin (BSA) protein with different surfactants under varying solution conditions. We show that the interaction of anionic BSA protein (pH7) with surfactant and the resultant structure are strongly modified by the charge head group of the surfactant, ionic strength of the solution, and mixed surfactants. The protein-surfactant interaction is maximum when two components are oppositely charged, followed by components being similarly charged through the site-specific binding, and no interaction in the case of a nonionic surfactant. This interaction of protein with ionic surfactants is characterized by the fractal structure representing a bead-necklace structure of micellelike clusters adsorbed along the unfolded protein chain. The interaction is enhanced with ionic strength only in the case of site-specific binding of an anionic surfactant with an anionic protein, whereas it is almost unchanged for other complexes of cationic and nonionic surfactants with anionic proteins. Interestingly, the interaction of BSA protein with ionic surfactants is significantly suppressed in the presence of nonionic surfactant. These results with mixed surfactants thus can be used to fold back the unfolded protein as well as to prevent surfactant-induced protein unfolding. For different solution conditions, the results are interpreted in terms of a change in fractal dimension, the overall size of the protein-surfactant complex, and the number of micelles attached to the protein. The interplay of electrostatic and hydrophobic interactions is found to govern the resultant structure of complexes.

  1. 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.

  2. 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 th

  3. Metathesis depolymerizable surfactants

    Science.gov (United States)

    Jamison, Gregory M.; Wheeler, David R.; Loy, Douglas A.; Simmons, Blake A.; Long, Timothy M.; McElhanon, James R.; Rahimian, Kamyar; Staiger, Chad L.

    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.

  4. Effects of Surfactant on Solubility and Microbial Conversion of Steroid

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Enhancing the dispersion and dissolution of substrate particles in substrate/water suspension is a feasible way to improve steroid bioconversion. The aim of the present study is to investigate the effects of applying surfactant to microbial conversion system on the dispersion, solubilization and in turn bioconversion of steroid substrate. The model system is hydroxylation of substrate 16α-,17α-epoxy-4-pregnene-3,20-dine by microbial enzymes from Rhizopus nigricanl. The results show that the presence of substrate leads to an increase in critical micelle concentration (CMC) of surfactant PSE compared with the normal CMC of PSE in aqueous solution. The grinding time during substrate suspension preparation affects the substrate aqueous solubility differently with the varied surfactant concentrations while barely making any difference in substrate solubility in the absence of surfactant. The properly prolonged grinding time can make up for the loss in substrate solubility arising from the reduction in surfactant concentration. The surfactant complexes composed of surfactants PSE and MGE at appropriate ratios are screened out with orthodoxy experiment method, the interaction between PSE and MGE exerts the most prominent effects on substrate bioconversion, and the surfactant complexes show more beneficial effects on steroid bioconversion than the surfactant PSE used alone.

  5. 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.

  6. 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

  7. Effect of surfactant on surface hardness of dental stone and investment casts produced from polyvinyl siloxane duplicating materials.

    Science.gov (United States)

    Al-Johani, Attalah; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2008-06-01

    Polyvinylsiloxane duplicating materials are typically treated with a topical surfactant before pouring dental models, but the use of topical surfactants in the dental laboratory may affect the surface hardness of the resultant models. The effect of two different topical surfactants on surface hardness of two dental stones (FujiRock and Dentstone) and one phosphate bonded investment material (Croform WB) produced from polyvinyl siloxane (PVS) dental laboratory duplicating moulds was investigated. Topical surfactants affected the surface hardness of FujiRock, Dentstone and Croform WB investment material. Surface hardness of FujiRock increased with Wax-Mate surfactant. However, surface hardness of Croform WB investment material decreased with both topical surfactants.

  8. Removal of 226Ra and 228Ra from TENORM sludge waste using surfactants solutions.

    Science.gov (United States)

    Attallah, M F; Hamed, Mostafa M; El Afifi, E M; Aly, H F

    2015-01-01

    The feasibility of using surfactants as extracting agent for the removal of radium species from TENORM sludge produced from petroleum industry is evaluated. In this investigation cationic and nonionic surfactants were used as extracting agents for the removal of radium radionuclides from the sludge waste. Two surfactants namely cetyltrimethylammonium bromide (CTAB) and Triton X-100 (TX100) were investigated as the extracting agents. Different parameters affecting the removal of both (226)Ra and (228)Ra by the two surfactants as well as their admixture were studied by the batch technique. These parameters include effect of shaking time, surfactants concentration and temperature as well as the effect of surfactants admixture. It was found that, higher solution temperature improves the removal efficiency of radium species. Combined extraction of nonionic and cationic surfactants produces synergistic effect in removal both (226)Ra and (228)Ra, where the removals reached 84% and 80% for (226)Ra and (228)Ra, respectively, were obtained using surfactants admixture.

  9. Removal of cationic surfactant (CTAB from aqueous solution on to activated carbon obtained from corncob.

    Directory of Open Access Journals (Sweden)

    S. M. Yakout

    2009-05-01

    Full Text Available Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before water is released to the environment or delivered for public use. Using powdered activated carbon (PAC as adsorbent may be an effective technique to remove surfactants. In this study, the removal of surfactants by PAC was investigated and the influencesof the operating parameters on the effectiveness on adsorption rate were studied. Cationic surfactant, Cetyl trimethyl ammonium bromide (CTAB was selected for the experiments. A series of batch experiments were performed to determine the sorption isotherms of surfactants to PAC. The results showed that carbon structure affect mainly on the surfactant adsorption. Surfactant equilibrium data fitted very well to the binary langmuir model. The pseudo first-,second- order and intraparticle diffusion kinetic models were applied. Both, the external mass transfer and intraparticle diffusion mechanisms involve in CTAB sorption.

  10. Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Voisin, David

    2002-07-01

    Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and

  11. 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.

  12. Surfactant apoprotein in nonmalignant pulmonary disorders.

    Science.gov (United States)

    Singh, G.; Katyal, S. L.

    1980-01-01

    Formalin-fixed, paraffin-embedded lungs exhibiting a variety of nonmalignant disorders were studied by immunoperoxidase staining using antibodies specific for surfactant apoprotein, IgG, IgM, IgA, albumin, fibrinogen, and lysozyme. Normal Type II pneumocytes showed staining for surfactant apoprotein in the perinuclear region only. The extent and intensity of staining for apoprotein was markedly increased in reactive Type II pneumocytes. This increase appeared to be a nonspecific reaction to lung injury. The intra-alveolar material in pulmonary alveolar proteinosis stained intensely for surfactant apoprotein, indicating that the accumulated proteinaceous material contained pulmonary surfactant. Type II pneumocytes in pulmonary alveolar proteinosis exhibited hyperplasia as well as hypertrophy. The few macrophages in lung affected by pulmonary alveolar proteinosis stained intensely for lysozyme. The excessive intraalveolar accumulation of proteinaceous material in pulmonary alveolar proteinosis may be the result of both an over-production as well as a deficient removal of pulmonary surfactant. Images Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 p[57]-a PMID:7004201

  13. How Do the Size, Charge and Shape of Nanoparticles Affect Amyloid β Aggregation on Brain Lipid Bilayer?

    Science.gov (United States)

    Kim, Yuna; Park, Ji-Hyun; Lee, Hyojin; Nam, Jwa-Min

    2016-01-19

    Here, we studied the effect of the size, shape, and surface charge of Au nanoparticles (AuNPs) on amyloid beta (Aβ) aggregation on a total brain lipid-based supported lipid bilayer (brain SLB), a fluid platform that facilitates Aβ-AuNP aggregation process. We found that larger AuNPs induce large and amorphous aggregates on the brain SLB, whereas smaller AuNPs induce protofibrillar Aβ structures. Positively charged AuNPs were more strongly attracted to Aβ than negatively charged AuNPs, and the stronger interactions between AuNPs and Aβ resulted in fewer β-sheets and more random coil structures. We also compared spherical AuNPs, gold nanorods (AuNRs), and gold nanocubes (AuNCs) to study the effect of nanoparticle shape on Aβ aggregation on the brain SLB. Aβ was preferentially bound to the long axis of AuNRs and fewer fibrils were formed whereas all the facets of AuNCs interacted with Aβ to produce the fibril networks. Finally, it was revealed that different nanostructures induce different cytotoxicity on neuroblastoma cells, and, overall, smaller Aβ aggregates induce higher cytotoxicity. The results offer insight into the roles of NPs and brain SLB in Aβ aggregation on the cell membrane and can facilitate the understanding of Aβ-nanostructure co-aggregation mechanism and tuning Aβ aggregate structures.

  14. Responsive Aqueous Foams Stabilized by Silica Nanoparticles Hydrophobized in Situ with a Conventional Surfactant.

    Science.gov (United States)

    Zhu, Yue; Pei, Xiaomei; Jiang, Jianzhong; Cui, Zhenggang; Binks, Bernard P

    2015-12-01

    In the recent past, switchable surfactants and switchable/stimulus-responsive surface-active particles have been of great interest. Both can be transformed between surface-active and surface-inactive states via several triggers, making them recoverable and reusable afterward. However, the synthesis of these materials is complicated. In this paper we report a facile protocol to obtain responsive surface-active nanoparticles and their use in preparing responsive particle-stabilized foams. Hydrophilic silica nanoparticles are initially hydrophobized in situ with a trace amount of a conventional cationic surfactant in water, rendering them surface-active such that they stabilize aqueous foams. The latter can then be destabilized by adding equal moles of an anionic surfactant, and restabilized by adding another trace amount of the cationic surfactant followed by shaking. The stabilization-destabilization of the foams can be cycled many times at room temperature. The trigger is the stronger electrostatic interaction between the oppositely charged surfactants than that between the cationic surfactant and the negatively charged particles. The added anionic surfactant tends to form ion pairs with the cationic surfactant, leading to desorption of the latter from particle surfaces and dehydrophobization of the particles. Upon addition of another trace amount of cationic surfactant, the particles are rehydrophobized in situ and can then stabilize foams again. This principle makes it possible to obtain responsive surface-active particles using commercially available inorganic nanoparticles and conventional surfactants.

  15. Photosensitive surfactants: micellization and interaction with DNA.

    Science.gov (United States)

    Zakrevskyy, Yuriy; Roxlau, Julian; Brezesinski, Gerald; Lomadze, Nino; Santer, Svetlana

    2014-01-28

    Recently, photosensitive surfactants have re-attracted considerable attention. It has been shown that their association with oppositely charged biologically important polyelectrolytes, such as DNA or microgels, can be efficiently manipulated simply by light exposure. In this article, we investigate the self-assembly of photosensitive surfactants as well as their interactions with DNA by calorimetric and spectroscopic methods. Critical micelle concentration (CMC), standard micellization enthalpy, entropy, and Gibbs energy were determined in different conditions (ionic strengths and temperatures) for a series of cationic surfactants with an azobenzene group in their tail. It is shown, that aggregation forces of photosensitive units play an important role in the micellization giving the major contribution to the micellization enthalpy. The onset of the aggregation can be traced from shift of the absorption peak position in the UV-visible spectrum. Titration UV-visible spectroscopy is used as an alternative, simple, and sensitive approach to estimate CMC. The titration UV-visible spectroscopy was also employed to investigate interactions (CAC: critical aggregation concentration, precipitation, and colloidal stabilization) in the DNA-surfactant complex.

  16. Photosensitive surfactants: Micellization and interaction with DNA

    Science.gov (United States)

    Zakrevskyy, Yuriy; Roxlau, Julian; Brezesinski, Gerald; Lomadze, Nino; Santer, Svetlana

    2014-01-01

    Recently, photosensitive surfactants have re-attracted considerable attention. It has been shown that their association with oppositely charged biologically important polyelectrolytes, such as DNA or microgels, can be efficiently manipulated simply by light exposure. In this article, we investigate the self-assembly of photosensitive surfactants as well as their interactions with DNA by calorimetric and spectroscopic methods. Critical micelle concentration (CMC), standard micellization enthalpy, entropy, and Gibbs energy were determined in different conditions (ionic strengths and temperatures) for a series of cationic surfactants with an azobenzene group in their tail. It is shown, that aggregation forces of photosensitive units play an important role in the micellization giving the major contribution to the micellization enthalpy. The onset of the aggregation can be traced from shift of the absorption peak position in the UV-visible spectrum. Titration UV-visible spectroscopy is used as an alternative, simple, and sensitive approach to estimate CMC. The titration UV-visible spectroscopy was also employed to investigate interactions (CAC: critical aggregation concentration, precipitation, and colloidal stabilization) in the DNA-surfactant complex.

  17. Fibrinogen stability under surfactant interaction.

    Science.gov (United States)

    Hassan, Natalia; Barbosa, Leandro R S; Itri, Rosangela; Ruso, Juan M

    2011-10-01

    Differential scanning calorimetry (DSC), circular dichroism (CD), difference spectroscopy (UV-vis), Raman spectroscopy, and small-angle X-ray scattering (SAXS) measurements have been performed in the present work to provide a quantitatively comprehensive physicochemical description of the complexation between bovine fibrinogen and the sodium perfluorooctanoate, sodium octanoate, and sodium dodecanoate in glycine buffer (pH 8.5). It has been found that sodium octanoate and dodecanoate act as fibrinogen destabilizer. Meanwhile, sodium perfluorooctanoate acts as a structure stabilizer at low molar concentration and as a destabilizer at high molar concentration. Fibrinogen's secondary structure is affected by all three studied surfactants (decrease in α-helix and an increase in β-sheet content) to a different extent. DSC and UV-vis revealed the existence of intermediate states in the thermal unfolding process of fibrinogen. In addition, SAXS data analysis showed that pure fibrinogen adopts a paired-dimer structure in solution. Such a structure is unaltered by sodium octanoate and perfluoroctanoate. However, interaction of sodium dodecanoate with the fibrinogen affects the protein conformation leading to a complex formation. Taken together, all results evidence that both surfactant hydrophobicity and tail length mediate the fibrinogen stability upon interaction.

  18. Micellization of monomeric and poly-ω-methacryloyloxyundecyltrimethylammonium surfactants.

    Science.gov (United States)

    FitzGerald, Paul A; Chatjaroenporn, Khwanrat; Zhang, Xiaoli; Warr, Gregory G

    2011-10-04

    We have used small-angle neutron scattering to study how micelle morphology of the tail-polymerizable surfactants MUTAB and MUTAC (ω-methacryloyloxyundecyltrimethylammonium bromide and chloride) is affected by classic self-assembly modifiers such as temperature changes, salt addition, and counterion exchange, as a function of their conversion from monomer into polymer amphiphile in aqueous solution. Contrary to common assumptions about polymerized surfactants, these systems remain in dynamic equilibrium under all conditions examined and at all conversions (except for a small amount of high-molecular-weight precipitation by MUTAC). Counterintuitively, the polymerized methacrylate backbone has little influence on aggregate morphology, except for the formation of rod-like mixed micelles of polymerized and unpolymerized surfactant at intermediate conversions. The addition of salt produces a transition to rod-like micelles at all conversions except in the unpolymerized surfactant, which has some characteristics of an asymmetric bolaform surfactant and retains its spheroidal geometry under almost all conditions.

  19. Surfactant-Amino Acid and Surfactant-Surfactant Interactions in Aqueous Medium: a Review.

    Science.gov (United States)

    Malik, Nisar Ahmad

    2015-08-01

    An overview of surfactant-amino acid interactions mainly in aqueous medium has been discussed. Main emphasis has been on the solution thermodynamics and solute-solvent interactions. Almost all available data on the topic has been presented in a lucid and simple way. Conventional surfactants have been discussed as amphiphiles forming micelles and amino acids as additives and their effect on the various physicochemical properties of these conventional surfactants. Surfactant-surfactant interactions in aqueous medium, various mixed surfactant models, are also highlighted to assess their interactions in aqueous medium. Finally, their applied part has been taken into consideration to interpret their possible uses.

  20. Competitive adsorption of surfactants and hydrophilic silica particles at the oil-water interface: interfacial tension and contact angle studies.

    Science.gov (United States)

    Pichot, R; Spyropoulos, F; Norton, I T

    2012-07-01

    The effect of surfactants' type and concentration on the interfacial tension and contact angle in the presence of hydrophilic silica particles was investigated. Silica particles have been shown to have an antagonistic effect on interfacial tension and contact angle in the presence of both W/O and O/W surfactants. Silica particles, combined with W/O surfactant, have no effect on interfacial tension, which is only dictated by the surfactant concentration, while they strongly affect interfacial tension when combined with O/W surfactants. At low O/W surfactant, both particles and surfactant are adsorbed at the interface, modifying the interface structure. At higher concentration, interfacial tension is only dictated by the surfactant. By increasing the surfactant concentration, the contact angle that a drop of aqueous phase assumes on a glass substrate placed in oil media decreases or increases depending on whether the surfactant is of W/O or O/W type, respectively. This is due to the modification of the wettability of the glass by the oil or water induced by the surfactants. Regardless of the surfactant's type, the contact angle profile was dictated by both particles and surfactant at low surfactant concentration, whereas it is dictated by the surfactant only at high concentration.

  1. Deformation and stability of surfactant - or particle - laden drop

    Science.gov (United States)

    Brosseau, Quentin; Pradillo, Gerardo; Oberlander, Andrew; Vlahovska, Petia; SoftMech@Brown Team

    2015-11-01

    We present an experimental study of the behavior of a drop covered with insoluble surfactant or colloidal particles in a uniform DC electric field. Steady drop shapes, drop evolution upon application of the field, and drop relaxation after the field is turned off are observed for leaky dielectric fluids: Polybutadiene (PB), Silicon oil (PDMS), and Castor oil (CO). The surfactant is generated at the drop interface by reaction between end-functionalized PB and PDMS. The experimental data is compared with existing theoretical models for the steady shape of surfactant covered droplet, and adjusted models taking into account the presence of colloidal spheres with range of electrical properties. We will discuss the complex interplay of shape deformation, surfactant elasticity, particle redistribution, and interfacial charging in droplet electrohydrodynamics. Our results are important for understanding electrorheology of emulsions commonly found in the petroleum industry. We acknowledge grant NSF CBET 1437545 for funding.

  2. Mechanisms for lowering of interfacial tension in alkali/acidic oil systems; Effect of added surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Rudin, J. Wasan, D.T. (Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering)

    1992-08-01

    This paper reports that experimental studies are conducted in order to determine the physicochemical mechanism responsible for lowering of interfacial tension in alkali, surfactant, and surfactant-enhanced alkali/acidic oil systems. A well-defined model oil is chosen to examine the influence of various surfactants and surfactant mixtures, such as oleic acid and its ionic counterpart, sodium dodecyl sulfate, petroleum sulfonate, and isobutanol, on equilibrium interfacial tension. With added surfactant alone, the interfacial tension goes through an ultralow minimum with increasing acid concentration. This proves for the first time that the un-ionized acid species plays a major role in affecting interfacial tension, and the ionized acid species.

  3. Self Assembly of Biogenic Surfactants at Mineral Surfaces and Their Effect on Biological Iron Acquisition

    Science.gov (United States)

    Kraemer, S. M.

    2005-12-01

    Microorganisms exude biogenic surfactants to modify the physical and chemical properties of mineral-water interfaces. Surfactants with negatively charged hydrophilic head groups interact strongly with oppositely charged mineral surfaces such as iron or aluminum oxides. Surfactant self assembly at mineral surfaces can result in the formation of admicelles that have a significant effect on the surface charge and hydrophobicity. These effects are exploited by microorganisms to facilitate attachment to mineral surfaces. Similarly, plants exude surfactants into the rhizosphere and change the surface tension and flow of soil water. Other surface active compounds that are typically found in soils and surface waters are humic substances and fatty acids that are produced by degradation of biomass. In general, surface active compounds are ubiquitous in natural systems. In this study we investigated how surfactants influence bio-mineral interactions using the example of siderophore promoted iron acquisition. Siderophore promoted iron acquisition involves the adsorption of a biogenic iron specific ligand (i.e. the siderophore) to iron oxides and the subsequent siderophore promoted iron oxide dissolution. The hypothesis of this project is that the modification of the iron oxide surface charge and hydrophobicity by adsorbed surfactants will have an important effect on siderophore adsorption and dissolution kinetics. We approached this subject by investigating the adsorption of a natural surfactant (rhamnolipids: RhL) and the synthetic surfactant (sodium dodecyl sulfate: SDS) on goethite (α-FeOOH, a common pedogenic iron oxide) and observing the effect of surfactant self assembly on the properties of the mineral water interface. We observed fast adsorption kinetics at pH 3 and slow adsorption at pH 6. The adsorbed surfactants reversed the surface potential of goethite (as evidenced by electrophoretic mobility measurements) at soluble surfactant concentrations below 10 μM (SDS

  4. Perfluorinated Alcohols Induce Complex Coacervation in Mixed Surfactants.

    Science.gov (United States)

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

    2016-03-15

    (-)) whereas the two counterions (Br(-) and Na(+)) primarily reside in the aqueous-rich phase. The results suggest the formation of a catanionic complex in the coacervate phase through ion pairing with a concomitant release of the surfactant counterions (Na(+) and Br(-)) into the aqueous-rich phase. Finally, the fluorocarbon alcohol systems are contrasted with the effects of aliphatic alcohols in the mixed catanionic surfactant systems. Isopropanol does not have the same interactions as HFIP with respect to solubilization, aggregation, and phase separation of the oppositely charged surfactants.

  5. Sublethal effect of agronomical surfactants on the spider Pardosa agrestis.

    Science.gov (United States)

    Niedobová, Jana; Hula, Vladimír; Michalko, Radek

    2016-06-01

    In addition to their active ingredients, pesticides contain also additives - surfactants. Use of surfactants has been increasing over the past decade, but their effects on non-target organisms, especially natural enemies of pests, have been studied only very rarely. The effect of three common agrochemical surfactants on the foraging behavior of the wolf spider Pardosa agrestis was studied in the laboratory. Differences in short-term, long-term, and overall cumulative predatory activities were investigated. We found that surfactant treatment significantly affected short-term predatory activity but had no effect on long-term predatory activity. The surfactants also significantly influenced the cumulative number of killed prey. We also found the sex-specific increase in cumulative kills after surfactants treatment. This is the first study showing that pesticide additives have a sublethal effect that can weaken the predatory activity of a potential biological control agent. More studies on the effects of surfactants are needed to understand how they affect beneficial organisms in agroecosystems.

  6. Sizing up surfactant synthesis.

    Science.gov (United States)

    Han, SeungHye; Mallampalli, Rama K

    2014-08-01

    Phosphatidylcholine is generated through de novo synthesis and remodeling involving a lysophospholipid. In this issue of Cell Metabolism, research from the Shimizu lab (Harayama et al., 2014) demonstrates the highly selective enzymatic behavior of lysophospholipid acyltransferases. The authors present an enzymatic model for phosphatidylcholine molecular species diversification that impacts surfactant formation.

  7. Mechanistic study of wettability alteration of oil-wet sandstone surface using different surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Bao-feng, E-mail: hbf370283@163.com; Wang, Ye-fei; Huang, Yong

    2015-03-01

    Graphical abstract: Zeta potential of oil-wet quartz powder treated with different surfactants at different concentrations. - Highlights: • Mechanisms of wettability alteration during surfactant flooding were studied. • Different analytical instruments were used to study sandstone wettability alteration. • Surfactants’ structure plays a great role in wettability alteration of solid surface. • CTAB irreversibly desorbs carboxylic acid from solid surface by ionic interaction. • Cationic surfactant is more effective in wettability alteration of sandstone surface. - Abstract: Different analytical methods including Fourier transform infrared (FTIR), atomic force microscopy (AFM), zeta potential measurements, contact angle measurements and spontaneous imbibition tests were utilized to make clear the mechanism for wettability alteration of oil-wet sandstone surface using different surfactants. Results show that among three types of surfactants including cationic surfactants, anionic surfactants and nonionic surfactants, the cationic surfactant CTAB demonstrates the best effect on the wettability alteration of oil-wet sandstone surface. The positively charged head groups of CTAB molecules and carboxylic acid groups from crude oil could interact to form ion pairs, which could be desorbed from the solid surface and solubilized into the micelle formed by CTAB. Thus, the water-wetness of the solid surface is improved. Nonionic surfactant TX-100 could be adsorbed on oil-wet sandstone surface through hydrogen bonds and hydrophobic interaction to alter the wettability of oil-wet solid surface. The wettability alteration of oil-wet sandstone surface using the anionic surfactant POE(1) is caused by hydrophobic interaction. Due to the electrostatic repulsion between the anionic surfactant and the negatively charged surface, POE(1) shows less effect on the wettability alteration of oil-wet sandstone surface.

  8. Large scale molecular dynamics study of polymer-surfactant complex

    Science.gov (United States)

    Goswami, Monojoy; Sumpter, Bobby

    2012-02-01

    In this work, we study the self-assembly of cationic polyelectrolytes mediated by anionic surfactants in dilute or semi-dilute and gel states. The understanding of the dilute system is a requirement for the understanding of gel states. The importance of polyelectrolyte with oppositely charged colloidal particles can be found in biological systems, such as immobilization of enzymes in polyelectrolyte complexes or nonspecific association of DNA with protein. With the same understanding, interaction of surfactants with polyelectrolytes shows intriguing phenomena that are important for both in academic research as well as industrial applications. Many useful properties of PE surfactant complexes come from the highly ordered structures of surfactant self-assembly inside the PE aggregate. We do large scale molecular dynamics simulation using LAMMPS to understand the structure and dynamics of PE-surfactant systems. Our investigation shows highly ordered ring-string structures that have been observed experimentally in biological systems. We will investigate many different properties of PE-surfactant complexation which will be helpful for pharmaceutical, engineering and biological applications.

  9. Reduction of surface charges during coalescence of elastomer particles.

    Science.gov (United States)

    Gauer, Cornelius; Wu, Hua; Morbidelli, Massimo

    2010-07-15

    Reaction-limited aggregation of soft elastomer particles has been studied with specific attention to the fate of surface charges during coalescence. The employed system is an aqueous dispersion of fluoroelastomer particles, which are known to coalesce completely at 70 degrees C. In contrast to diffusion-limited conditions, under reaction-limited conditions the stability of the system is expected to change during aggregation because of surface reduction and charge accumulation resulting from coalescence. This allows investigating the mechanism of charge relocation during cluster coalescence. For particles stabilized by ionic surfactants, it has been found that the charges are mobile (i.e., they redistribute between aqueous solution and particle surface according to their adsorption equilibrium) (Gauer, C.; Jia, Z.; Wu, H.; Morbidelli, M. Langmuir 2009, 25, 9703). In this work, we consider the case of fixed charges, as those given by charged polymer end groups covalently bound to the particle surface. We demonstrate that a loss of fixed surface charges occurs during the coalescence and strongly affects the time evolution and the shape of the resulting cluster mass distribution.

  10. Weak nonlinear surface-charging effects in electrolytic films.

    Science.gov (United States)

    Dean, D S; Horgan, R R

    2003-11-01

    A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full nonlinear surface terms which are then treated at a one-loop level by calculating the mean-field Poisson-Boltzmann solution and then the fluctuations about this solution. We carefully analyze the renormalization of the theory and apply it to a triple-layer model for a thin film with Stern layer of thickness h. For this model we give expressions for the surface charge sigma(L) and the disjoining pressure P(d)(L) and show their dependence on the parameters. The influence of image charges naturally arises in the formalism, and we show that predictions depend strongly on h because of their effects. In particular, we show that the surface charge vanishes as the film thickness L-->0. The fluctuation terms in this class of theories contribute a Casimir-like attraction across the film. Although this attraction is well known to be negligible compared with the mean-field component for model electrolytic films with no surface-charge regulation, in the model studied here these fluctuations also affect the surface-charge regulation leading to a fluctuation component in the disjoining pressure which has the same behavior as the mean-field component even for large film thickness.

  11. Effect of the head-group geometry of amino acid-based cationic surfactants on interaction with plasmid DNA.

    Science.gov (United States)

    Jadhav, Vaibhav; Maiti, Souvik; Dasgupta, Antara; Das, Prasanta Kumar; Dias, Rita S; Miguel, Maria G; Lindman, Björn

    2008-07-01

    The interaction between DNA and different types of amino acid-based cationic surfactants was investigated. Particular attention was directed to determine the extent of influence of surfactant head-group geometry toward tuning the interaction behavior of these surfactants with DNA. An overview is obtained by gel retardation assay, isothermal titration calorimetry, fluorescence spectroscopy, and circular dichroism at different mole ratios of surfactant/DNA; also, cell viability was assessed. The studies show that the surfactants with more complex/bulkier hydrophobic head group interact more strongly with DNA but exclude ethidium bromide less efficiently; thus, the accessibility of DNA to small molecules is preserved to a certain extent. The presence of more hydrophobic groups surrounding the positive amino charge also gave rise to a significantly lower cytotoxicity. The surfactant self-assembly pattern is quite different without and with DNA, illustrating the roles of electrostatic and steric effects in determining the effective shape of a surfactant molecule.

  12. CHARGE syndrome

    Directory of Open Access Journals (Sweden)

    Prasad Chitra

    2006-09-01

    Full Text Available Abstract CHARGE syndrome was initially defined as a non-random association of anomalies (Coloboma, Heart defect, Atresia choanae, Retarded growth and development, Genital hypoplasia, Ear anomalies/deafness. In 1998, an expert group defined the major (the classical 4C's: Choanal atresia, Coloboma, Characteristic ears and Cranial nerve anomalies and minor criteria of CHARGE syndrome. Individuals with all four major characteristics or three major and three minor characteristics are highly likely to have CHARGE syndrome. However, there have been individuals genetically identified with CHARGE syndrome without the classical choanal atresia and coloboma. The reported incidence of CHARGE syndrome ranges from 0.1–1.2/10,000 and depends on professional recognition. Coloboma mainly affects the retina. Major and minor congenital heart defects (the commonest cyanotic heart defect is tetralogy of Fallot occur in 75–80% of patients. Choanal atresia may be membranous or bony; bilateral or unilateral. Mental retardation is variable with intelligence quotients (IQ ranging from normal to profound retardation. Under-development of the external genitalia is a common finding in males but it is less apparent in females. Ear abnormalities include a classical finding of unusually shaped ears and hearing loss (conductive and/or nerve deafness that ranges from mild to severe deafness. Multiple cranial nerve dysfunctions are common. A behavioral phenotype for CHARGE syndrome is emerging. Mutations in the CHD7 gene (member of the chromodomain helicase DNA protein family are detected in over 75% of patients with CHARGE syndrome. Children with CHARGE syndrome require intensive medical management as well as numerous surgical interventions. They also need multidisciplinary follow up. Some of the hidden issues of CHARGE syndrome are often forgotten, one being the feeding adaptation of these children, which needs an early aggressive approach from a feeding team. As the child

  13. MICROBIAL SURFACTANTS. II. LIPOPEPTIDES

    Directory of Open Access Journals (Sweden)

    T. P. Pirog

    2014-04-01

    Full Text Available The classification and the chemical structure of the lipopeptides and their producers (bacteria of the genera Bacillus and Pseudomonas are given. The role of the lipopeptides in cells motility, biofilm formation, metal binding and xenobiotics degradation and their action on the cells of pro- and eukaryotes is summarized. The stages of the nonribosomal lipopeptides synthesis and the role of two-component (GacA/GacS, ComA/ComP and the quorum system regulation of this process are shown. The potential of lactic acid bacteria and marine microorganisms as alternative surfactants producers (glycolipids, lipopeptides, phospholipids and fatty acids, glycolipopeptides are discussed. Their productivity and advantages over traditional producers are given as well. The properties of surfactants synthesized by lactic acid bacteria (the reduction of the surface tension, the critical micelle concentration, the stability in a wide range of pH, the temperature, the biological activity are summarized. Surfactants of nonpathogenic probiotic bacteria could be used as effective antimicrobial agents and antiadhesive and marine producers which able to synthesize unique metabolites that are not produced by other microorganisms.

  14. Comparative insight into surfactants mediated amyloidogenesis of lysozyme.

    Science.gov (United States)

    Chaturvedi, Sumit K; Khan, Javed M; Siddiqi, Mohammad K; Alam, Parvez; Khan, Rizwan H

    2016-02-01

    Electrostatic and hydrophobic interactions have an important role in the protein aggregation. In this study, we have investigated the effect of charge and hydrophobicity of oppositely charged surfactants i.e., anionic (AOT and SDS) and cationic (CTAB and DTAB) on hen egg white lysozyme at pH 9.0 and 13.0, respectively. We have employed various methods such as turbidity measurements, Rayleigh light scattering, ThT, Congo red and ANS dye binding assays, far-UV CD, atomic force microscopy, transmission electron and fluorescence microscopy. At lower molar ratio, both anionic and cationic surfactants promote amyloid fibril formation in lysozyme at pH 9.0 and 13.0, respectively. The aggregation was proportionally increased with respect to protein concentration and hydrophobicity of surfactant. The morphology of aggregates at both the pH was fibrillar in structure, as visualized by dye binding and microscopic imaging techniques. Initially, the interaction between surfactants and lysozyme was electrostatic and then hydrophobic as investigated by ITC. This study demonstrates the crucial role of charge and hydrophobicity during amyloid fibril formation.

  15. Solubilization capacity of nonionic surfactant micelles exhibiting strong influence on export of intracellular pigments in Monascus fermentation.

    Science.gov (United States)

    Kang, Biyu; Zhang, Xuehong; Wu, Zhenqiang; Qi, Hanshi; Wang, Zhilong

    2013-09-01

    In this study, perstractive fermentation of intracellular Monascus pigments in nonionic surfactant micelle aqueous solution had been studied. The permeability of cell membrane modified by nonionic surfactant might have influence on the rate of export of intracellular pigments into its extracellular broth while nearly no effect on the final extracellular pigment concentration. However, the solubilization of pigments in nonionic surfactant micelles strongly affected the final extracellular pigment concentration. The solubilization capacity of micelles depended on the kind of nonionic surfactant, the super-molecule assembly structure of nonionic surfactant in an aqueous solution, and the nonionic surfactant concentration. Elimination of pigment degradation by export of intracellular Monascus pigments and solubilizing them into nonionic surfactant micelles was also confirmed experimentally. Thus, nonionic surfactant micelle aqueous solution is potential for replacement of organic solvent for perstractive fermentation of intracellular product.

  16. Gemini ester quat surfactants and their biological activity.

    Science.gov (United States)

    Łuczyński, Jacek; Frąckowiak, Renata; Włoch, Aleksandra; Kleszczyńska, Halina; Witek, Stanisław

    2013-03-01

    Cationic gemini surfactants are an important class of surface-active compounds that exhibit much higher surface activity than their monomeric counterparts. This type of compound architecture lends itself to the compound being easily adsorbed at interfaces and interacting with the cellular membranes of microorganisms. Conventional cationic surfactants have high chemical stability but poor chemical and biological degradability. One of the main approaches to the design of readily biodegradable and environmentally friendly surfactants involves inserting a bond with limited stability into the surfactant molecule to give a cleavable surfactant. The best-known example of such a compound is the family of ester quats, which are cationic surfactants with a labile ester bond inserted into the molecule. As part of this study, a series of gemini ester quat surfactants were synthesized and assayed for their biological activity. Their hemolytic activity and changes in the fluidity and packing order of the lipid polar heads were used as the measures of their biological activity. A clear correlation between the hemolytic activity of the tested compounds and their alkyl chain length was established. It was found that the compounds with a long hydrocarbon chain showed higher activity. Moreover, the compounds with greater spacing between their alkyl chains were more active. This proves that they incorporate more easily into the lipid bilayer of the erythrocyte membrane and affect its properties to a greater extent. A better understanding of the process of cell lysis by surfactants and of their biological activity may assist in developing surfactants with enhanced selectivity and in widening their range of application.

  17. Nature of the Intermicellar Interactions in Ethoxylated Polysorbate Surfactants with High Degrees of Ethoxylation.

    Science.gov (United States)

    Penfold, J; Thomas, R K; Li, P X; Tucker, I; Petkov, J; Petkova, R E

    2016-02-09

    Ethoxylated polysorbate Tween nonionic surfactants are extensively used as foam and emulsion stabilizers and in aqueous solution form globular micelles. The ethoxylated polysorbate surfactants with higher degrees of ethoxylation than the Tween surfactants exhibit some interesting self-assembly properties. Small-angle neutron scattering, SANS, measurements have revealed intermicellar interactions which are more pronounced than the hard-sphere excluded volume interactions normally associated with nonionic surfactant micelles. The interactions are interpreted as arising from the partial charge on the ether oxygen of the ethylene oxide groups. This gives rise to an effective net negative charge on the micelles, which has been determined from the SANS data and zeta potential measurements. For degrees of ethoxylation of ⩽20, the effect is relatively small. The interaction increases with increasing ethoxylation such that for a degree of ethoxylation of 50 the interaction is comparable to that of ionic surfactant micelles. Unlike the intermicellar interaction in ionic surfactant micellar solutions, which results from the charge on the micelle arising from the partial binding of counterions, the interaction between ethoxthylated polysorbate surfactant micelles is unaffected by the addition of electrolyte.

  18. Alteration in cell surface properties of Burkholderia spp. during surfactant-aided biodegradation of petroleum hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Sagarika; Mukherji, Suparna [Indian Institute of Technology Bombay, Mumbai (India). Centre for Environmental Science and Engineering (CESE)

    2012-04-15

    Chemical surfactants may impact microbial cell surface properties, i.e., cell surface hydrophobicity (CSH) and cell surface charge, and may thus affect the uptake of components from non-aqueous phase liquids (NAPLs). This work explored the impact of Triton X-100, Igepal CA 630, and Tween 80 (at twice the critical micelle concentration, CMC) on the cell surface characteristics of Burkholderia cultures, Burkholderia cepacia (ES1, aliphatic degrader) and Burkholderia multivorans (NG1, aromatic degrader), when grown on a six-component model NAPL. In the presence of Triton X-100, NAPL biodegradation was enhanced from 21% to 60% in B. cepacia and from 18% to 53% in B. multivorans. CSH based on water contact angle (50-52 ) was in the same range for both strains while zeta potential at neutral pH was -38 and -31 mV for B. cepacia and B. multivorans, respectively. In the presence of Triton X-100, their CSH increased to greater than 75 and the zeta potential decreased. This induced a change in the mode of uptake and initiated aliphatic hydrocarbon degradation by B. multivorans and increased the rate of aliphatic hydrocarbon degradation in B. cepacia. Igepal CA 630 and Tween 80 also altered the cell surface properties. For B. cepacia grown in the presence of Triton X-100 at two and five times its CMC, CSH increased significantly in the log growth phase. Growth in the presence of the chemical surfactants also affected the abundance of chemical functional groups on the cell surface. Cell surface changes had maximum impact on NAPL degradation in the presence of emulsifying surfactants, Triton X-100 and Igepal CA630.

  19. Interaction of nonionic surfactant AEO9 with ionic surfactants

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-guo; YIN Hong

    2005-01-01

    The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, αAEO9 =0.5. The surface properties of the surfactants, critical micelle concentration (CMC),effectiveness of surface tension reduction (γCMC), maximum surface excess concentration (Гmax) and minimum area per molecule at the air/solution interface (Amin) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were determined. Mixtures of both AEO9/SDS and AEO9/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness.

  20. Electrophoretic separations in poly(dimethylsiloxane) microchips using mixtures of ionic, nonionic and zwitterionic surfactants.

    Science.gov (United States)

    Guan, Qian; Noblitt, Scott D; Henry, Charles S

    2012-09-01

    The use of surfactant mixtures to affect both EOF and separation selectivity in electrophoresis with PDMS substrates is reported, and capacitively coupled contactless conductivity detection is introduced for EOF measurement on PDMS microchips. First, the EOF was measured for two nonionic surfactants (Tween 20 and Triton X-100), mixed ionic/nonionic surfactant systems (SDS/Tween 20 and SDS/Triton X-100), and finally for the first time, mixed zwitterionic/nonionic surfactant systems (TDAPS/Tween 20 and TDAPS/Triton X-100). EOF for the nonionic surfactants decreased with increasing surfactant concentration. The addition of SDS or TDAPS to a nonionic surfactant increased EOF. After establishing the EOF behavior, the separation of model catecholamines was explored to show the impact on separations. Similar analyte resolution with greater peak heights was achieved with mixed surfactant systems containing Tween 20 and TDAPS relative to the single surfactant system. Finally, the detection of catecholamine release from PC12 cells by stimulation with 80 mM K(+) was performed to demonstrate the usefulness of mixed surfactant systems to provide resolution of biological compounds in complex samples.

  1. 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.

  2. Surfactant adsorption kinetics in microfluidics

    Science.gov (United States)

    Riechers, Birte; Maes, Florine; Akoury, Elias; Semin, Benoît; Gruner, Philipp; Baret, Jean-Christophe

    2016-10-01

    Emulsions are metastable dispersions. Their lifetimes are directly related to the dynamics of surfactants. We design a microfluidic method to measure the kinetics of adsorption of surfactants to the droplet interface, a key process involved in foaming, emulsification, and droplet coarsening. The method is based on the pH decay in the droplet as a direct measurement of the adsorption of a carboxylic acid surfactant to the interface. From the kinetic measurement of the bulk equilibration of the pH, we fully determine the adsorption process of the surfactant. The small droplet size and the convection during the droplet flow ensure that the transport of surfactant through the bulk is not limiting the kinetics of adsorption. To validate our measurements, we show that the adsorption process determines the timescale required to stabilize droplets against coalescence, and we show that the interface should be covered at more than 90% to prevent coalescence. We therefore quantitatively link the process of adsorption/desorption, the stabilization of emulsions, and the kinetics of solute partitioning—here through ion exchange—unraveling the timescales governing these processes. Our method can be further generalized to other surfactants, including nonionic surfactants, by making use of fluorophore-surfactant interactions.

  3. 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...

  4. 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

  5. Dielectrophoresis of a surfactant-laden viscous drop

    Science.gov (United States)

    Mandal, Shubhadeep; Bandopadhyay, Aditya; Chakraborty, Suman

    2016-06-01

    The dielectrophoresis of a surfactant-laden viscous drop in the presence of non-uniform DC electric field is investigated analytically and numerically. Considering the presence of bulk-insoluble surfactants at the drop interface, we first perform asymptotic solution for both low and high surface Péclet numbers, where the surface Péclet number signifies the strength of surface convection of surfactants as compared to the diffusion at the drop interface. Neglecting fluid inertia and interfacial charge convection effects, we obtain explicit expression for dielectrophoretic drop velocity for low and high Péclet numbers by assuming small deviation of drop shape from sphericity and small deviation of surfactant concentration from the equilibrium uniform distribution. We then depict a numerical solution, assuming spherical drop, for arbitrary values of Péclet number. Our analyses demonstrate that the asymptotic solution shows excellent agreement with the numerical solution in the limiting conditions of low and high Péclet numbers. The present analysis shows that the flow-induced redistribution of the surfactants at the drop interface generates Marangoni stress, owing to the influence of the surfactant distribution on the local interfacial tension, at the drop interface and significantly alters the drop velocity at steady state. For a perfectly conducting/dielectric drop suspended in perfectly dielectric medium, Marangoni stress always retards the dielectrophoretic velocity of the drop as compared with a surfactant-free drop. For a leaky dielectric drop suspended in another leaky dielectric medium, in the low Péclet number limit, depending on the electrical conductivity and permittivity of both the liquids, the Marangoni stress may aid or retard the dielectrophoretic velocity of the drop. The Marangoni stress also has the ability to move the drop in the opposite direction as compared with a surfactant-free drop. This non-intuitive reverse motion of the drop is

  6. Biophysicochemical Interaction of a Clinical Pulmonary Surfactant with Nanoalumina.

    Science.gov (United States)

    Mousseau, F; Le Borgne, R; Seyrek, E; Berret, J-F

    2015-07-01

    We report on the interaction of pulmonary surfactant composed of phospholipids and proteins with nanometric alumina (Al2O3) in the context of lung exposure and nanotoxicity. We study the bulk properties of phospholipid/nanoparticle dispersions and determine the nature of their interactions. The clinical surfactant Curosurf, both native and extruded, and a protein-free surfactant are investigated. The phase behavior of mixed surfactant/particle dispersions was determined by optical and electron microscopy, light scattering, and zeta potential measurements. It exhibits broad similarities with that of strongly interacting nanosystems such as polymers, proteins or particles, and supports the hypothesis of electrostatic complexation. At a critical stoichiometry, micron-sized aggregates arising from the association between oppositely charged vesicles and nanoparticles are formed. Contrary to the models of lipoprotein corona or of particle wrapping, our work shows that vesicles maintain their structural integrity and trap the particles at their surfaces. The agglomeration of particles in surfactant phase is a phenomenon of importance that could change the interactions of the particles with lung cells.

  7. Solubilization isotherms of aromatic solutes in surfactant aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Gadelle, F.; Koros, W.J.; Schechter, R.S. (Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering)

    1995-03-01

    Several factors affecting solubilization of aromatic solutes in surfactant micelles have been investigated. Solubilization isotherms of benzene, toluene, and chlorobenzene in various aqueous micellar solutions were determined using head space gas chromatography. Cationic surfactants such as cetylpyridinium chloride or cetyltrimethylammonium bromide present high solubilization capacities. Comparable anionic surfactants exhibit lower solubilization and a greater tendency to precipitate. It was observed that nonionic surfactants show high solubilization on a molar basis. Solubilization in mixed cationic-anionic micelles was also investigated. It also appears that the molecular size of the solute determines the extent of the solubilization. Finally, the shape of the different isotherms indicates that knowing the amount solubilized at saturation of the micellar solution is not sufficient to estimate solubilization at solute concentrations lower than the solute aqueous solubility. Solubilization of organics in surfactant micelles is of major importance in many applications. One new application is micellar-enhanced ultrafiltration. Another application of interest is the surfactant-enhanced aquifer remediation, a process in which a micellar aqueous solution is flushed into contaminated groundwaters to enhance recovery of pollutants by micellar solubilization.

  8. Barrier or carrier? Pulmonary surfactant and drug delivery.

    Science.gov (United States)

    Hidalgo, Alberto; Cruz, Antonio; Pérez-Gil, Jesús

    2015-09-01

    To consider the lung as a target for drug delivery and to optimise strategies directed at the pulmonary route, it is essential to consider the role of pulmonary surfactant, a thin lipid-protein film lining the respiratory surface of mammalian lungs. Membrane-based surfactant multilayers are essential for reducing the surface tension at the respiratory air-liquid interface to minimise the work of breathing. Different components of surfactant are also responsible for facilitating the removal of potentially pathological entities such as microorganisms, allergens or environmental pollutants and particles. Upon inhalation, drugs or nanoparticles first contact the surfactant layer, and these interactions critically affect their lifetime and fate in the airways. This review summarises the current knowledge on the possible role and effects of the pulmonary surfactant system in drug delivery strategies. It also summarises the evidence that suggests that pulmonary surfactant is far from being an insuperable barrier and could be used as an efficient shuttle for delivering hydrophobic and hydrophilic compounds deep into the lung and the organism.

  9. Improving reseeding success after catastrophic wildfire - shifting the paradigm with surfactant seed coatings

    Science.gov (United States)

    The application of soil surfactants in wildfire-affected ecosystems has been limited due to logistical and economic constraints associated with the standard practice of using large quantities of irrigation water as the surfactant carrier. We tested a potential solution to this problem that uses seed...

  10. Improving reseeding success after catastrophic wildfire with surfactant seed coating technology

    Science.gov (United States)

    The application of soil surfactants in wildfire-affected ecosystems has been limited due to logistical and economic constraints associated with the standard practice of using large quantities of irrigation water as the surfactant carrier. We tested a potential solution to this problem that uses seed...

  11. Aggregation Kinetics and Transport of Single-Walled CarbonNanotubes at Low Surfactant Concentrations

    Science.gov (United States)

    Little is known about how low levels of surfactants can affect the colloidal stability of single-walled carbon nanotubes (SWNTs) and how surfactant-wrapping of SWNTs can impact ecological exposures in aqueous systems. In this study, SWNTs were suspended in water with sodium ...

  12. Innovation in surfactant therapy II: surfactant administration by aerosolization.

    Science.gov (United States)

    Pillow, J Jane; Minocchieri, S

    2012-01-01

    Instilled bolus surfactant is the only approved surfactant treatment for neonatal respiratory distress syndrome. However, recent trends towards increased utilization of noninvasive respiratory support for preterm infants with surfactant deficiency have created a demand for a similarly noninvasive means of administering exogenous surfactant. Past approaches to surfactant nebulization met with varying success due to inefficient aerosol devices resulting in low intrapulmonary delivery doses of surfactant with variable clinical effectiveness. The recent development of vibrating membrane nebulizers, coupled with appropriate positioning of the interface device, indicates that efficient delivery of aerosolized surfactant is now a realistic goal in infants. Evidence of clinical effect despite low total administered dose in pilot studies, together with suggestions of enhanced homogeneity of pulmonary distribution indicate that this therapy may be applied in a cost-effective manner, with minimal patient handling and disruption. These studies need to be subjected to appropriately designed randomized controlled trials. Further work is also required to determine the optimum delivery route (mask, intranasal prong, nasopharyngeal or laryngeal), dosing amount and redosing interval.

  13. A study of polymer-surfactant interactions by neutron reflectivity

    CERN Document Server

    Warren, N

    1999-01-01

    surfactants and their relative levels of interaction with the polymer. The surface behaviour of these systems was observed to be in many ways more remarkable than that of the bulk solution. In the high total surfactant concentration range, once all polymer molecules were associated with bound micelles, the extent of adsorption at the air-liquid interface was found to be dominated largely, as might be expected, by the solution monomer concentrations of the two surfactants. Prior to this, however, adsorption was dominated by the presence of a very surface active polymer-SDS complex which gave rise to enhanced SDS adsorption and low surface tensions compared with those found in polymer-free systems. The origin of this effect, being the stabilisation of the adsorbed SDS monolayer due to a reduction in the inter-headgroup repulsions through screening, by the charged polymer segments, suggests that this may be a characteristic feature of systems continuing a polyelectrolyte and an oppositely charged surfactant. In ...

  14. Viscoelasticity Enhancement of Surfactant Solutions Depends on Molecular Conformation: Influence of Surfactant Headgroup Structure and Its Counterion.

    Science.gov (United States)

    Lutz-Bueno, Viviane; Pasquino, Rossana; Liebi, Marianne; Kohlbrecher, Joachim; Fischer, Peter

    2016-05-03

    During the anisotropic growth from globular to wormlike micelles, the basic interactions among distinct parts of the surfactant monomer, its counterion, and additives are fundamental to tune molecular self-assembly. We investigate the addition of sodium salicylate (NaSal) to hexadecyltrimethylammonium chloride and bromide (CTAC and CTAB), 1-hexadecylpyridinium chloride and bromide (CPyCl and CPyBr), and benzyldimethylhexadecylammonium chloride (BDMC), which have the same hydrophobic tail. Their potential to enhance viscoelasticity by anisotropic micellar growth upon salt addition was compared in terms of (i) the influence of the headgroup structure, and (ii) the influence of surfactant counterion type. Employing proton nuclear magnetic resonance ((1)H NMR), we focused on the molecular conformation of surfactant monomers in the core and polar shell regions of the micelles and their interactions with increasing concentration of NaSal. The viscoelastic response was investigated by rotational and oscillatory rheology. We show that micellar growth rates can be tuned by varying the flexibility and size of the surfactant headgroup as well as the dissociation degree of the surfactant counterion, which directly influences the strength of headgroup-counterion pairing. As a consequence, the morphological transitions depend directly on charge neutralization by electrostatic screening. For example, the amount of salt necessary to start the rodlike-to-wormlike micelle growth depends directly on the number of dissociated counterions in the polar shell.

  15. Interaction of nonionic surfactant AEO9 with ionic surfactants*

    OpenAIRE

    2005-01-01

    The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, α AEO9=0.5. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (γ CMC), maximum surface excess concentration (Γ max) and minimum area per...

  16. Lichenysin-geminal amino acid-based surfactants: Synergistic action of an unconventional antimicrobial mixture.

    Science.gov (United States)

    Coronel-León, Jonathan; Pinazo, Aurora; Pérez, Lourdes; Espuny, Mª José; Marqués, Ana Mª; Manresa, Angeles

    2017-01-01

    Recently it has been demonstrated that catanionic mixtures of oppositely charged surfactants have improved physicochemical-biological properties compared to the individual components. Isotherms of mixtures of an anionic biosurfactant (lichenysin) and a cationic aminoacid surfactant (C3(LA)2) indicate a strong interaction suggesting the formation of a new "pseudo-surfactant". The antimicrobial properties of the mixture lichenysin and C3(LA)2 M80:20, indicate a synergistic effect of the components. The mechanism of action on the bacterial envelope was assessed by flow cytometry and Transmission Electron Microscopy.

  17. 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.

  18. Binding of 12-s-12 dimeric surfactants to calf thymus DNA: Evaluation of the spacer length influence.

    Science.gov (United States)

    Sarrión, Beatriz; Bernal, Eva; Martín, Victoria Isabel; López-López, Manuel; López-Cornejo, Pilar; García-Calderón, Margarita; Moyá, María Luisa

    2016-08-01

    Several cationic dimeric surfactants have shown high affinity towards DNA. Bis-quaternary ammonium salts (m-s-m) have been the most common type of dimeric surfactants investigated and it is generally admitted that those that posses a short spacer (s≤3) show better efficiency to bind or compact DNA. However, experimental results in this work show that 12-s-12 surfactants with long spacers make the surfactant/ctDNA complexation more favorable than those with short spacers. A larger contribution of the hydrophobic interactions, which control the binding Gibbs energy, as well as a higher average charge of the surfactant molecules bound to the nucleic acid, which favors the electrostatic attractions, could explain the experimental observations. Dimeric surfactants with intermediate spacer length seem to be the less efficient for DNA binding.

  19. Surfactants present complex joint effects on the toxicities of metal oxide nanoparticles.

    Science.gov (United States)

    Wang, Dali; Lin, Zhifen; Yao, Zhifeng; Yu, Hongxia

    2014-08-01

    The potential toxicities of nanoparticles (NPs) have been intensively discussed over the past decade. In addition to their single toxicities, NPs can interact with other environmental chemicals and thereby exert joint effects on biological systems and the environment. The present study investigated the combined toxicities of NPs and surfactants, which are among the chemicals that most likely coexist with NPs. Photobacterium phosphoreum was employed as the model organism. The results indicate that surfactants with different ion types can alter the properties of NPs (i.e., particle size and surface charge) in different ways and present complex joint effects on NP toxicities. Mixtures of different NPs and surfactants exhibited antagonistic, synergistic, and additive effects. In particular, the toxicity of ZnO was observed to result from its dissolved Zn(2+); thus, the joint effects of the ZnO NPs and surfactants can be explained by the interactions between the Zn ions and the surfactants. Our study suggests that the potential hazards caused by mixtures of NPs and surfactants are different from those caused by single NPs. Because surfactants are extensively used in the field of nanotechnology and are likely to coexist with NPs in natural waters, the ecological risk assessments of NPs should consider the impacts of surfactants.

  20. Surfactant and metal ion effects on the mechanical properties of alginate hydrogels.

    Science.gov (United States)

    Kaygusuz, Hakan; Evingür, Gülşen Akın; Pekcan, Önder; von Klitzing, Regine; Erim, F Bedia

    2016-11-01

    This paper addresses the controlled variation of the mechanical properties of alginate gel beads by changing the alginate concentration or by adding different surfactants or cross-linking cations. Alginate beads containing nonionic Brij 35 or anionic sodium dodecyl sulfate (SDS) surfactants were prepared with two different types of cations (Ca(2+), Ba(2+)) as crosslinkers. Compression measurements were performed to investigate the effect of the surfactant and cation types and their concentrations on the Young's modulus of alginate beads. The Young's modulus was determined by using Hertz theory. For all types of alginate gel beads the Young's modulus showed an increasing value for increasing alginate contents. Addition of the anionic surfactant SDS increases the Young's modulus of the alginate beads while the addition of non-ionic surfactant Brij 35 leads to a decrease in Young's modulus. This opposite behavior is related to the contrary effect of both surfactants on the charge of the alginate beads. When Ba(2+) ions were used as crosslinker cation, the Young's modulus of the beads with the surfactant SDS was found to be approximately two times higher than the modulus of beads with the surfactant Brij 35. An ion specific effect was found for the crosslinking ability of divalent cations.

  1. Anaerobic Biodegradation of Detergent Surfactants

    Directory of Open Access Journals (Sweden)

    Erich Jelen

    2009-03-01

    Full Text Available Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have strictly anaerobic conditions. This review gives an overview on anaerobic biodegradation processes, the methods for testing anaerobic biodegradability, and the anaerobic biodegradability of different detergent surfactant types (anionic, nonionic, cationic, amphoteric surfactants.

  2. Formation and stability of nanoemulsions with mixed ionic-nonionic surfactants.

    Science.gov (United States)

    Wang, Lijuan; Tabor, Rico; Eastoe, Julian; Li, Xuefeng; Heenan, Richard K; Dong, Jinfeng

    2009-11-14

    A simple, low-energy two-step dilution process has been applied with binary mixtures of ionic-nonionic surfactants to prepare nanoemulsions. The systems consist of water/DDAB-C(12)E(5)/decane. Nanoemulsions were obtained by dilution of concentrates located in bicontinuous microemulsion or lamellar liquid crystal phase regions. The nanoemulsions generated were investigated both by contrast-variation small-angle neutron scattering (SANS) and dynamic light scattering (DLS). The SANS profiles show that C(12)E(5) nanodroplets suffer essentially no structural change on incorporation of the cationic DDAB surfactant, except for increased electrostatic repulsive interactions. Interestingly, SANS indicated that the preferred droplet sizes were hardly affected by the surfactant mixture composition (up to a DDAB molar ratio (m(DDAB)/(m(DDAB) + m(C(12)E(5))) of 0.40) and droplet volume fraction, phi, between 0.006 and 0.120. No notable changes in the structure or radius of nanoemulsion droplets were observed by SANS over the test period of 1 d, although the droplet number intensity decreased significantly in systems stabilized by C(12)E(5) only. However, the DLS sizing shows a marked increase with time, with higher droplet volume fractions giving rise to the largest changes. The discrepancy between apparent nanoemulsion droplet size determined by DLS and SANS data can be attributed to long-range droplet interactions occurring outside of the SANS sensitivity range. The combined SANS and DLS results suggest flocculation is the main mechanism of instability for these nanoemulsions. The flocculation rate is shown to be significantly retarded by addition of the charged DDAB, which may be due to enhanced electrostatic repulsive forces between droplets, leading to improved stability of the nanoemulsions.

  3. A conductometric investigation of hydroxypropylmethyl cellulose/sodium dodecyl sulfate/nonionic surfactant systems

    Directory of Open Access Journals (Sweden)

    Petrović Lidija B.

    2014-01-01

    Full Text Available Surfactant mixtures are very often used in various cosmetic and pharmaceutical products because they commonly act in synergism and provide more favorable properties than the single surfactants. At the same time, the 9 presence of polymers in mixtures of surfactants may lead to molecular interactions thereby affecting product stability and activity. For these reasons it is very important to determine the surfactant interactions influence on 1micellization and mixed micellization, as well as polymer-surfactants mixed micelles interactions. In this work we examined self-aggregation of nonionic surfactants, polysorbate 20 (Tween 20, polyoxyethylene octylphenyl ether (Triton X100 and polyoxyethylene-polyoxypropylene block copolymer (Pluronic F68 with ionic surfactant, sodium dodecylsulfate, in aqueous solution at 40ºC using conductometric titration method. It was found that concentration region for mixed micelle formation depends on nonionic surfactant characteristics and its concentration. Formation of surfactants mixed micelles in the presence of nonionic polymer, hydroxypropylmethyl cellulose, and their binding to polymer hydrophobic sites, were investigated too. Analysis of obtained results points to different kinds of interactions in investigated systems, which are crucial for their application. [Projekat Ministarstva nauke Republike Srbije, br. III 46010

  4. 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 metabol

  5. Electrochemical Oscillations Induced by Surfactants

    Institute of Scientific and Technical Information of China (English)

    翟俊红; 贺占博

    2003-01-01

    A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO4 aqueous and an aluminum rod in Al(NO3)3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg2SO4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.

  6. Persurf, a New Method to Improve Surfactant Delivery: A Study in Surfactant Depleted Rats

    OpenAIRE

    2012-01-01

    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 di...

  7. Mechanistic study of wettability alteration using surfactants with applications in naturally fractured reservoirs.

    Science.gov (United States)

    Salehi, Mehdi; Johnson, Stephen J; Liang, Jenn-Tai

    2008-12-16

    In naturally fractured reservoirs, oil recovery from waterflooding relies on the spontaneous imbibition of water to expel oil from the matrix into the fracture system. The spontaneous imbibition process is most efficient in strongly water-wet rock where the capillary driving force is strong. In oil- or mixed-wet fractured carbonate reservoirs, however, the capillary driving force for the spontaneous imbibition process is weak, and therefore the waterflooding oil recoveries are low. The recovery efficiency can be improved by dissolving low concentrations of surfactants in the injected water to alter the wettability of the reservoir rock to a more water-wet state. This wettability alteration accelerates the spontaneous imbibition of water into matrix blocks, thereby increasing the oil recovery during waterflooding. Several mechanisms have been proposed to explain the wettability alteration by surfactants, but none have been verified experimentally. Understanding of the mechanisms behind wettability alteration could help to improve the performance of the process and aid in identification of alternative surfactants for use in field applications. Results from this study revealed that ion-pair formation and adsorption of surfactant molecules through interactions with the adsorbed crude oil components on the rock surface are the two main mechanisms responsible for the wettability alteration. Previous researchers observed that, for a given rock type, the effectiveness of wettability alteration is highly dependent upon the ionic nature of the surfactant involved. Our experimental results demonstrated that ion-pair formation between the charged head groups of surfactant molecules and the adsorbed crude oil components on rock surface was more effective in changing the rock wettability toward a more water-wet state than the adsorption of surfactant molecules as a monolayer on the rock surface through hydrophobic interaction with the adsorbed crude oil components. By comparing

  8. Surfactant damages on coastal vegetation in southern Italy

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available Coastal vegetation decline caused by seaspray has been reported to affect a variety of species in several countries: Australia, South of France, along the Italian Tyrrhenian coast, Spain and Tunisia. The most serious injury is due to the interaction between sea salt and surfactants, even if surfactants may cause direct damage on cell membranes. The salt uptake is enhanced by the durfactant-induced erosion of the epicuticular wax, which reduces the water surface tension. The symptoms are non-specific and consist in leaf discoloration and necrosis. In needles, necrosis begins from the apex; in leaves, from the edges. Directionality of crown damage is the main symptom for diagnosing the involvement of polluted seaspray. If an obstacle is placed between trees and sea wind, the trees do not show appreciable damage. In Italy, the tree decline caused by seaspray and surfactants has been investigated with special reference to the pinewoods of the San Rossore (Tuscany, Central Italy, or on the Tyrrhenian coastlands of Central Italy, such as the area around Castelporziano in Lazio. This research is aimed at a preliminary assessment of the extent of surfactant damage to the coastal vegetation in four regions in Southern Italy by: i field surveys and mapping of damage caused by surfactants; ii detecting the presence of surfactants on the tree crowns. The damages have been observed in a lot of zones in Apulia, Basilicata, Campania and Calabria, within 500 m inland from the sea, for a maximum length of 5500 m coastline, near the mouth of a river or stream, near the outlet of sewage canals and in any other coastal areas where the surface currents carry a surfactant load.

  9. The role of surfactant treatment in preterm infants and term newborns with acute respiratory distress syndrome.

    Science.gov (United States)

    Wirbelauer, J; Speer, C P

    2009-05-01

    Surfactant treatment in preterm infants and term newborns with (acute respiratory distress syndrome) ARDS-like severe respiratory failure has become part of an individualized treatment strategy in many intensive care units around the world. These babies constitute heterogeneous groups of gestational ages, lung maturity, as well as of the underlying disease processes and postnatal interventions. The pathophysiology of respiratory failure in preterm infants is characterized by a combination of primary surfactant deficiency and surfactant inactivation as a result of plasma proteins leaking into the airways from areas of epithelial disruption and injury. Various pre- and postnatal factors, such as exposure to chorioamnionitis, pneumonia, sepsis and asphyxia, induce an injurious inflammatory response in the lungs of preterm infants, which may subsequently affect surfactant function, synthesis and alveolar stability. Surfactant inactivation--and dysfunction--is also a hallmark in newborns with meconium aspiration syndrome (MAS), pneumonia and other disorders affecting the pulmonary function. Although for the majority of suggested indications no data from randomized controlled trials exist, a surfactant replacement that counterbalances surfactant inactivation seems to improve oxygenation and lung function in many babies with ARDS without any apparent negative side effects. Newborns with MAS will definitely benefit from a reduced need for extracorporeal membrane oxygenation (ECMO). Clinical experience seems to justify surfactant treatment in neonates with ARDS.

  10. Specific interactions within micelle microenvironment in different charged dye/surfa

    Directory of Open Access Journals (Sweden)

    Adina Roxana Petcu

    2016-01-01

    Full Text Available The interactions of two ionic dyes, Crystal Violet and Methyl Orange, with different charged surfactants and also with a nonionic surfactant were investigated using surface tension measurements and visible spectroscopy in pre-micellar and post-micellar regions. It was found that for the water dominant phase systems the dye was localized between the polar heads, at the exterior of the direct micelle shells for all the systems. For the oil dominant phase systems, in case of the same charged dye/surfactant couples, the dye was localized in the micelle shell between the hydrocarbon chain of the surfactant nearby the hydrophilic head groups while for nonionic surfactant and oppositely charged dye/surfactant, localization of dye was between the oxyethylenic head groups towards the interior of the micelle core. Mixed aggregates of the dye and surfactant (below the critical micellar concentration of cationic surfactant, dye-surfactant ion pair and surfactant-micelles were present. The values of equilibrium constants (for TX-114/MO and TX-114/CV systems were 0.97 and 0.98, respectively, partition coefficients between the micellar and bulk water phases and standard free energy (for the nonionic systems were −12.59 kJ/mol for MO and −10.97 kJ/mol for CV were calculated for all the studied systems. The partition processes were exothermic and occurred spontaneously.

  11. Dynamics of surfactant-driven fracture of particle rafts.

    Science.gov (United States)

    Vella, Dominic; Kim, Ho-Young; Aussillous, Pascale; Mahadevan, L

    2006-05-05

    We investigate the dynamic fracture of a close-packed monolayer of particles, or particle raft, floating at a liquid-gas interface induced by the localized addition of surfactant. Unusually for a two-dimensional solid, our experiments show that the speed of crack propagation here is not affected by the elastic properties of the raft. Instead it is controlled by the rate at which surfactant is advected to the crack tip by means of the induced Marangoni flows. Further, the velocity of propagation is not constant in time and the length of the crack scales as t(3/4). More broadly, this surfactant-induced rupture of interfacial rafts suggests ways to manipulate them for applications.

  12. [Adsorption of phenol chemicals by surfactant-modified zeolites].

    Science.gov (United States)

    Xie, Jie; Wang, Zhe; Wu, De-Yi; Li, Chun-Jie

    2012-12-01

    Two kinds of zeolites were prepared from fly ash and modified by surfactant subsequently. Surfactant-modified zeolites were studied for adsorption of phenol chemicals (phenol, p-chlorphenol, bisphenol A). It showed that the adsorption affinity of zeolite to phenol chemicals was significantly improved after surfactant modification. The adsorption isotherms of phenol chemicals were well fitted by the Langmuir isotherm. For the two surfactant-surfactant modified zeolites, the maximum adsorption amounts of phenol, p-chlorphenol, and bisphenol A calculated from the Langmuir equation were 37.7, 52.36, 90.9 mg x g(-1) and 10.7, 22.83, 56.8 mg x g(-1), respectively. When pH values of solutions were higher than the pK(a) values of phenol chemicals, the removal efficiencies were getting higher with the increase of pH values. The octanol/water partition coefficient (K(ow)) was also found to be an important factor affecting adsorption of phenol chemicals by the modified zeolites. Higher K(ow) value, which means the greater hydrophobicity of the chemicals, resulted in a higher removal.

  13. Direct suppression of phagocytosis by amphipathic polymeric surfactants.

    Science.gov (United States)

    Watrous-Peltier, N; Uhl, J; Steel, V; Brophy, L; Merisko-Liversidge, E

    1992-09-01

    Recent studies have demonstrated that phagocytosis of colloidal particles by the mononuclear phagocytes of the liver and spleen can be controlled by either coating or stabilizing particulate carriers with the amphipathic polymeric surfactants, F108 and T908. These surfactants consist of copolymers of polypropylene oxide (PPO) and polyethylene oxide (PEO) and, when adsorbed to particulate surfaces, significantly decrease sequestration of particulates by the mononuclear phagocytes (MPS) of the liver. To evaluate these observations further, murine peritoneal macrophages were incubated for varying periods with surfactant-coated and noncoated polystyrene particles (PSPs). Phagocytosis was monitored using gamma counting and quantitative fluorescence microscopy. The data show that phagocytosis is decreased when PSPs are coated with F108 and T908. In addition, suppression of phagocytic activity was observed when cells were pretreated with the surfactant and then challenged with noncoated particles. The data confirm previous observations that polymeric surfactants consisting of PEO and PPO protect particulate carriers from rapid uptake by the MPS of the liver. Further, F108 and T908 suppress phagocytosis directly without affecting the integrity, viability, or functional state of the cell.

  14. Evaporation of Sessile Droplets Laden with Particles and Insoluble Surfactants.

    Science.gov (United States)

    Karapetsas, George; Chandra Sahu, Kirti; Matar, Omar K

    2016-07-12

    We consider the flow dynamics of a thin evaporating droplet in the presence of an insoluble surfactant and noninteracting particles in the bulk. On the basis of lubrication theory, we derive a set of evolution equations for the film height, the interfacial surfactant, and bulk particle concentrations, taking into account the dependence of liquid viscosity on the local particle concentration. An important ingredient of our model is that it takes into account the fact that the surfactant adsorbed at the interface hinders evaporation. We perform a parametric study to investigate how the presence of surfactants affects the evaporation process as well as the flow dynamics with and without the presence of particles in the bulk. Our numerical calculations show that the droplet lifetime is affected significantly by the balance between the ability of the surfactant to enhance spreading, suppressing the effect of thermal Marangoni stresses-induced motion, and to hinder the evaporation flux through the reduction of the effective interfacial area of evaporation, which tend to accelerate and decelerate the evaporation process, respectively. For particle-laden droplets and in the case of dilute solutions, the droplet lifetime is found to be weakly dependent on the initial particle concentration. We also show that the particle deposition patterns are influenced strongly by the direct effect of the surfactant on the evaporative flux; in certain cases, the "coffee-stain" effect is enhanced significantly. A discussion of the delicate interplay between the effects of capillary pressure and solutal and thermal Marangoni stresses, which drive the liquid flow inside of the evaporating droplet giving rise to the observed results, is provided herein.

  15. Phospholipid bilayer-perturbing properties underlying lysis induced by pH-sensitive cationic lysine-based surfactants in biomembranes.

    Science.gov (United States)

    Nogueira, Daniele Rubert; Mitjans, Montserrat; Busquets, M Antonia; Pérez, Lourdes; Vinardell, M Pilar

    2012-08-14

    Amino acid-based surfactants constitute an important class of natural surface-active biomolecules with an unpredictable number of industrial applications. To gain a better mechanistic understanding of surfactant-induced membrane destabilization, we assessed the phospholipid bilayer-perturbing properties of new cationic lysine-based surfactants. We used erythrocytes as biomembrane models to study the hemolytic activity of surfactants and their effects on cells' osmotic resistance and morphology, as well as on membrane fluidity and membrane protein profile with varying pH. The antihemolytic capacity of amphiphiles correlated negatively with the length of the alkyl chain. Anisotropy measurements showed that the pH-sensitive surfactants, with the positive charge on the α-amino group of lysine, significantly increased membrane fluidity at acidic conditions. SDS-PAGE analysis revealed that surfactants induced significant degradation of membrane proteins in hypo-osmotic medium and at pH 5.4. By scanning electron microscopy examinations, we corroborated the interaction of surfactants with lipid bilayer. We found that varying the surfactant chemical structure is a way to modulate the positioning of the molecule inside bilayer and, thus, the overall effect on the membrane. Our work showed that pH-sensitive lysine-based surfactants significantly disturb the lipid bilayer of biomembranes especially at acidic conditions, which suggests that these compounds are promising as a new class of multifunctional bioactive excipients for active intracellular drug delivery.

  16. Theoretical modeling of cationic surfactant aggregation at the silica/aqueous solution interface: Effects of pH and ionic strength

    NARCIS (Netherlands)

    Drach, M.; Andrzejewska, A.; Narkiewicz-Michalek, J.; Rudzinski, W.; Koopal, L.K.

    2002-01-01

    A theory of ionic surfactant aggregation on oppositely charged surfaces is presented. In the proposed model the adsorbed phase is considered as a mixture of singly dispersed surfactant molecules, monolayered and bilayered aggregates of various sizes and the ions of simple electrolyte added to the aq

  17. Hydrophobic, electrostatic, and dynamic polymer forces at silicone surfaces modified with long-chain bolaform surfactants.

    Science.gov (United States)

    Rapp, Michael V; Donaldson, Stephen H; Gebbie, Matthew A; Das, Saurabh; Kaufman, Yair; Gizaw, Yonas; Koenig, Peter; Roiter, Yuri; Israelachvili, Jacob N

    2015-05-06

    Surfactant self-assembly on surfaces is an effective way to tailor the complex forces at and between hydrophobic-water interfaces. Here, the range of structures and forces that are possible at surfactant-adsorbed hydrophobic surfaces are demonstrated: certain long-chain bolaform surfactants-containing a polydimethylsiloxane (PDMS) mid-block domain and two cationic α, ω-quarternary ammonium end-groups-readily adsorb onto thin PDMS films and form dynamically fluctuating nanostructures. Through measurements with the surface forces apparatus (SFA), it is found that these soft protruding nanostructures display polymer-like exploration behavior at the PDMS surface and give rise to a long-ranged, temperature- and rate-dependent attractive bridging force (not due to viscous forces) on approach to a hydrophilic bare mica surface. Coulombic interactions between the cationic surfactant end-groups and negatively-charged mica result in a rate-dependent polymer bridging force during separation as the hydrophobic surfactant mid-blocks are pulled out from the PDMS interface, yielding strong adhesion energies. Thus, (i) the versatile array of surfactant structures that may form at hydrophobic surfaces is highlighted, (ii) the need to consider the interaction dynamics of such self-assembled polymer layers is emphasized, and (iii) it is shown that long-chain surfactants can promote robust adhesion in aqueous solutions.

  18. Effect of surfactants and temperature on the hyperfiltration performance of poly(ether/urea) membranes

    Science.gov (United States)

    Leban, M. I.; Wydeven, T. J.

    1984-01-01

    The individual and combined effects of pasteurization temperature (347 K) and surfactants (anionic, cationic, and neutral) on a poly(ether/urea) thin-film hyperfiltration membrane were studied. Performance of this positively charged membrane was measured in terms of sodium chloride rejection and water flux. The observed effect was mostly on water flux and minimal on salt rejection. Pasteurization temperature caused an irreversible flux decline (flux decline slope of 0.09). The gradual flux reduction caused by neutral and cationic surfactants was reversible, whereas the flux reduction caused by anionic surfactant was irreversible and of similar magnitude to flux reduction caused by pasteurization temperature. The effects of anionic surfactant and pasteurization temperature were additive. Because of flux decline at elevated temperatures the poly(ether/urea) membrane is not very attractive for long-term spaceflight use.

  19. 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.

  20. Biophysicochemical interaction of a clinical pulmonary surfactant with nano-alumina

    CERN Document Server

    Mousseau, F; Seyrek, E; Berret, J -F

    2015-01-01

    We report on the interaction of pulmonary surfactant composed of phospholipids and proteins with nanometric alumina (Al2O3) in the context of lung exposure and nanotoxicity. We study the bulk properties of phospholipid/nanoparticle dispersions and determine the nature of their interactions. The clinical surfactant Curosurf, both native and extruded, and a protein-free surfactant are investigated. The phase behavior of mixed surfactant/particle dispersions was determined by optical and electron microscopy, light scattering and zeta potential measurements. It exhibits broad similarities with that of strongly interacting nanosystems such as polymers, proteins or particles, and supports the hypothesis of electrostatic complexation. At a critical stoichiometry, micron sized aggregates arising from the association between oppositely charged vesicles and nanoparticles are formed. Contrary to the models of lipoprotein corona or of particle wrapping, our work shows that vesicles maintain their structural integrity and...

  1. Effect of surfactants on shear-induced gelation and gel morphology of soft strawberry-like particles.

    Science.gov (United States)

    Xie, Delong; Arosio, Paolo; Wu, Hua; Morbidelli, Massimo

    2011-06-07

    The role of surfactant type in the aggregation and gelation of strawberry-like particles induced by intense shear without any electrolyte addition is investigated. The particles are composed of a rubbery core, partially covered by a plastic shell, and well stabilized by fixed (sulfate) charges in the end group of the polymer chains originating from the initiator. In the absence of any surfactant, after the system passes through a microchannel at a Peclet number equal to 220 and a particle volume fraction equal to 0.15, not only shear-induced gelation but also partial coalescence among the particles occurs. The same shear-induced aggregation/gelation process has been carried out in the presence of an ionic (sulfonate) surfactant or a nonionic (Tween 20) steric surfactant. It is found that for both surfactants shear-induced gelation does occur at low surfactant surface density but the conversion of the primary particles to the clusters constituting the gel decreases as the surfactant surface density increases. When the surfactant surface density increases above certain critical values, shear-induced gelation and eventually even aggregation do not occur any longer. For the sulfonate surfactant, this was explained in the literature by the non-DLVO, short-range repulsive hydration forces generated by the adsorbed surfactant layer. In this work, it is shown that the steric repulsion generated by the adsorbed Tween 20 layer can also protect particles from aggregation under intense shear. Moreover, the nonionic steric surfactant can also protect the strawberry-like particles from coalescence. This implies a decrease in the fractal dimension of the clusters constituting the gel from 2.76 to 2.45, which cannot be achieved using the ionic sulfonate surfactant.

  2. 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.

  3. Understanding How Isotopes Affect Charge Transfer in P3HT/PCBM: A Quantum Trajectory-Electronic Structure Study with Nonlinear Quantum Corrections.

    Science.gov (United States)

    Wang, Lei; Jakowski, Jacek; Garashchuk, Sophya; Sumpter, Bobby G

    2016-09-13

    The experimentally observed effect of selective deuterium substitution on the open circuit voltage for a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM; Nat. Commun. 2014, 5, 3180) is explored using a 221-atom model of a polymer-wrapped PCBM molecule. The protonic and deuteronic wave functions for the H/D isotopologues of the hexyl side chains are described within a quantum trajectory/electronic structure approach where the dynamics is performed with newly developed nonlinear corrections to the quantum forces, necessary to describe the nuclear wave functions; the classical forces are generated with a density functional tight binding method. The resulting protonic and deuteronic time-dependent wave functions are used to assess the effects of isotopic substitution (deuteration) on the energy gaps relevant to the charge transfer for the donor and acceptor electronic states. While the isotope effect on the electronic energy levels is found negligible, the quantum-induced fluctuations of the energy gap between the charge transfer and charge separated states due to nuclear wave functions may account for experimental trends by promoting charge transfer in P3HT:PCBM and increasing charge recombination on the donor in the deuterium substituted P3HT:PCBM.

  4. Surfactant recovery from water using foam fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Tharapiwattananon, N.; Osuwan, S. [Chulalongkorn Univ., Bangkok (Thailand); Scamehorn, J.F. [Inst. of Oklahoma, Norman, OK (United States)] [and others

    1996-05-01

    The purpose of this study was to investigate the use of foam fractionation to recover surfactant from water. A simple continuous mode foam fractionation was used and three surfactants were studied (two anionic and one cationic). The effects of air flow rate, foam height, liquid height, liquid feed surfactant concentration, and sparger porosity were studied. This technique was shown to be effective in either surfactant recovery or the reduction of surfactant concentration in water to acceptable levels. As an example of the effectiveness of this technique, the cetylpyridinium chloride concentration in water can be reduced by 90% in one stage with a liquid residence time of 375 minutes. The surfactant concentration in the collapsed foam is 21.5 times the feed concentration. This cationic surfactant was easier to remove from water by foam fractionation than the anionic surfactants studied.

  5. Synthesis of carbohydrate-based surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Pemberton, Jeanne E.; Polt, Robin L.; Maier, Raina M.

    2016-11-22

    The present invention provides carbohydrate-based surfactants and methods for producing the same. Methods for producing carbohydrate-based surfactants include using a glycosylation promoter to link a carbohydrate or its derivative to a hydrophobic compound.

  6. Adsorption Behavior and Mechanisms of Surfactants by Farmland Soils in Northeast China

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The adsorption of two nonionic surfactants polyethylene glycol tert-octylphenyl ether Triton X-100 (TX-100), polyoxyethylene lauryl ether(Brij35) and an anionic surfactant sodium dodecyl benzene sulfonate(SDBS) by two soils(S1, S2) of different natures and their respective organic-matter-extracted samples(S3, S4) were investigated. These adsorption isotherms show different adsorption stages of different types of surfactants by soils. The data fitted Langmuir equation very well. The adsorption maximum capacity(Q0) indicates that TX-100 and SDBS were in the sequence of S3〉S4〉S1〉S2 in adsorption, however, Brij35 was in the sequence of S4〉S3〉S1〉S2 in adsorption. And the adsorption amounts of the different surfactants by soils followed the order of TX-100〉Brij35〉SDBS. Meanwhile, the adsorption of the nonionic surfactants TX-100 and Brij35 decreased with the increase of their ethylene oxide(EO) numbers. The results indicate that both soil organic matter and mineral played important roles in the adsorption of surfactants, and the adsorption of the surfactants by soils was affected by the physicochemical properties and structures of the soils and surfactants, especially the mineral type and content of soil.

  7. Desorption of two organophosphorous pesticides from soil with wastewater and surfactant solutions.

    Science.gov (United States)

    Hernández-Soriano, M C; Mingorance, M D; Peña, A

    2012-03-01

    A batch test was used to evaluate the extent of desorption of diazinon and dimethoate, preadsorbed on a calcareous agricultural soil, representative of the Mediterranean area. Urban wastewater from a secondary treatment and seven surfactant solutions, at concentrations ranging from 0.75 mg L(-1) to 10 gL(-1), were used. The surfactants assayed were cationic (hexadecyl trimethyl ammonium bromide (HD)), anionic (sodium dodecyl sulfate (SDS), Aerosol 22 (A22) and Biopower (BP)), and nonionic (Tween 80 (TW), Triton X 100 (TX) and Glucopon 600 (G600)). Desorption of dimethoate was either not affected or only slightly by the nonionic and anionic surfactants tested, while desorption of diazinon from the soil was only enhanced by A22, BP and TW. This desorption increase correlated significantly with the surfactant concentration of the solution used for desorption and with the concurrent increase in the supernatant of the dissolved organic carbon, in particular that originating from the surfactant. This parameter did not vary with the use of SDS, G600 and TX. The cationic surfactant HD was retained on the soil surface, as confirmed by an increase in soil organic carbon, resulting in a fall in desorption rate for both pesticides. Comparing treatment by wastewater with control water, there was no difference in desorption rate for either pesticide. Mixed TW/anionic surfactant solutions either did not modify or slightly increased desorption of both pesticides in comparison with individual surfactant solutions.

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

    Science.gov (United States)

    Mah, Pei T; Peltonen, Leena; Novakovic, Dunja; Rades, Thomas; Strachan, Clare J; Laaksonen, Timo

    2016-06-01

    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 in a significant improvement on the dissolution behavior of binary polymer based solid dispersion. Incorporating the surfactant to the formulation to form ternary solid dispersion adversely affected the dissolution behavior. In conclusion, the use of surfactants (as wetting or solubilization agents) in dissolution studies of neat amorphous drugs requires prudent consideration. The design of amorphous formulations with optimal dissolution performance requires the appropriate selection of a combination of excipients and consideration of the method of introducing the excipients.

  9. Complex Formation Between Polyelectrolytes and Ionic Surfactants

    OpenAIRE

    1998-01-01

    The interaction between polyelectrolyte and ionic surfactant is of great importance in different areas of chemistry and biology. In this paper we present a theory of polyelectrolyte ionic-surfactant solutions. The new theory successfully explains the cooperative transition observed experimentally, in which the condensed counterions are replaced by ionic-surfactants. The transition is found to occur at surfactant densities much lower than those for a similar transition in non-ionic polymer-sur...

  10. Determination of methylene blue biosorption by Rhizopus arrhizus in the presence of surfactants with different chemical structures.

    Science.gov (United States)

    Karatay, Sevgi Ertuğrul; Gül, Ulküye Dudu; Dönmez, Gönül

    2014-10-03

    Methylene blue (MB) biosorption properties of Rhizopus arrhizus were investigated in the presence of surfactants. The effects of cationic and anionic surfactants on MB removal by dead biomass (1 g L(-1)) were determined. MB removal was tested as a function of initial pH (2-12), contact time (5-1440 min), and dye (37.4-944.7 mg L(-1)) and surfactant (0-10 mM) concentrations. The opposite charged anionic surfactant dodecylbenzenesulfonic acid sodium salt (DBS) enhanced sorption of cationic MB by biomass dramatically. Maximum biosorption capacity was 471.5 mg g(-1) at pH 8 with 0.5 mM DBS at 944.7 mg L(-1) MB concentration. The surfactant-stimulated fungal decolorization method may provide a highly efficient, inexpensive, and time-saving procedure in biological wastewater treatment technologies.

  11. Surfactant analysis in oil-containing fluids

    Energy Technology Data Exchange (ETDEWEB)

    Gronsveld, J.; Faber, M.J. (Koninklijke Shell Exploratie en Produktie Laboratorium, Rijswijk (Netherlands))

    The total surfactant concentration in aqueous phase samples can be analysed with a potentiometric titration. In enhanced oil recovery research, however, the surfactant is produced not only in aqueous phase samples but also in oleic phase samples. The oleic constituents in the oliec phase samples interfere in the surfactant analysis and, therefore, the titration method has been adapted. (orig.).

  12. 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

  13. Structure of DNA-Cationic Surfactant Complexes at Hydrophobically Modified and Hydrophilic Silica Surfaces as Revealed by Neutron Reflectometry

    DEFF Research Database (Denmark)

    Cardenas Gomez, Marite; Wacklin, Hanna; Campbell, Richard A.;

    2011-01-01

    layer structure (the location, coverage, and conformation the e DNA and surfactant molecules). Neutron reflectometry is the technique of choice for revealing the surface layer structure by means of selective deuteration. We start by studying the interfacial complexation of DNA...... with dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB) on hydrophobic surfaces, where we show that DNA molecules are located on top of a self-assembled surfactant monolayer, with the thickness of the DNA layer and the surfactant DNA ratio determined by the surface coverage of the underlying...... cationic layer. The surface coverages of surfactant and DNA are determined by the bulk concentration of the surfactant relative to its critical micelle concentration (cmc). The structure of the interfacial layer is not affected by the choice of cationic surfactant studied. However, to obtain similar...

  14. Interaction between cationic surfactant of 1-methyl-3-tetradecylimidazolium bromide and anionic polymer of sodium polystyrene sulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qian [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); School of Chemistry and Chemical Engineering, Engineering Research Center for Fine Chemicals of Ministry of Education, Shanxi University, Shanxi Province, VIC 030006 (China); Kang, Wenpei [Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Shandong Province, VIC 250100 (China); Sun, Dezhi [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); Liu, Jie, E-mail: liujie@lcu.edu.cn [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China); Wei, Xilian, E-mail: weixilian@126.com [College of Chemistry and Chemical Engineering, Liaocheng University, Shandong Province, VIC 252059 (China)

    2013-08-15

    The interaction between long-chain imidazolium ionic liquid (C{sub 14}mimBr) and anionic polyelectrolyte of sodium polystyrene sulfonate (NaPSS) has been studied using surface tension, isothermal titration microcalorimetry (ITC), dynamic light scatting (DLS) and conductance methods. The result shows that the surface tension plots have a pronounced hump in the surface tension at surfactant concentrations below the critical micelle concentration (cmc) of the surfactant. The cooperative adsorption of surfactant and polymer on the surface (PS{sub S}) and the formation of polymer/surfactant aggregate in bulk solution (PS{sub M}) provide a rational explanation about it. The formation of surfactant/polymer complexes is affected by the concentration of the surfactant or NaPSS, which is also ascertained by ITC and DLS measurements. Further, the thermodynamic parameters are derived from calorimetric titration and conductance curves, and the effects of polymer concentration and temperature on the parameters are evaluated in detail.

  15. Removal of organic pollutants by surfactant modified zeolite: Comparison between ionizable phenolic compounds and non-ionizable organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Jie; Meng, Wenna [School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Rd., Shanghai 200240 (China); Wu, Deyi, E-mail: dywu@sjtu.edu.cn [School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Rd., Shanghai 200240 (China); Zhang, Zhenjia; Kong, Hainan [School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Rd., Shanghai 200240 (China)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Surfactant modified zeolite could greatly retain organic pollutants. Black-Right-Pointing-Pointer Uptake of organic compounds was due to the loaded surfactant. Black-Right-Pointing-Pointer k{sub ow} is crucial for the uptake of both ionizable and non-ionizable organic solutes. Black-Right-Pointing-Pointer pK{sub a} is another factor affecting adsorption process of ionizable organic pollutants. Black-Right-Pointing-Pointer Adsorption mechanisms of the two kinds of organic pollutants were proposed. - Abstract: The aim of this study was to examine the adsorption capability and mechanism of hexadecyltrimethylammonium modified zeolite, which was synthesized from coal fly ash, for the removal of ionizable phenolic compounds (phenol, p-chlorophenol and bisphenol A, with different pK{sub a}) and non-ionizable organic compounds (aniline, nitrobenzene, and naphthalene, with different hydrophobicity). The obtained zeolite was identified as type Na-P1 (Na{sub 6}Al{sub 6}Si{sub 10}O{sub 32}{center_dot}12H{sub 2}O, JCPDS code 39-0219), which is classified into the gismondine group with a pore size of 3.1 Angstrom-Sign Multiplication-Sign 4.5 Angstrom-Sign [1 0 0] and 2.8 Angstrom-Sign Multiplication-Sign 4.8 Angstrom-Sign [1 0 1]. The adsorption of the two kinds of organic compounds was due to loaded surfactant bilayer because modified zeolite showed great ability for the removal of organic chemicals while little adsorption by zeolite was observed. The isotherm data of ionizable compounds fitted well to the Langmuir model but those of non-ionizable chemicals followed a linear equation. Uptake of ionizable compounds depended greatly on pH, increasing at alkaline pH conditions. In contrary, adsorption of non-ionizable chemicals was essentially the same at all pH levels studied. The adsorption of both kinds of organic compounds correlated well to k{sub ow} value, suggesting that more hydrophobic organic contaminants are more easily retained

  16. Fabrication of novel microstructures based on orientation-dependent adsorption of surfactant molecules in a TMAH solution

    Science.gov (United States)

    Pal, Prem; Sato, K.; Gosalvez, M. A.; Tang, B.; Hida, H.; Shikida, M.

    2011-01-01

    In this work, the orientation-dependent adsorption of surfactant molecules on the silicon surface during etching in surfactant-added tetramethylammonium hydroxide (TMAH) is investigated. Triton X-100 (C14H22O(C2H4O)n, n = 9-10) and 25 wt% TMAH are used as surfactant and main etchant, respectively. The crystallographic planes affected by the surfactant molecules are determined by analyzing the etching behavior of different mask patterns on Si{1 0 0} wafers and silicon hemispheres in pure and surfactant-added TMAH. Taken together, the shapes of the etched profiles and the analysis of the hemispherical etch rates confirm that thick and dense adsorbed surfactant layers are typically formed on both the exact and vicinal Si{1 1 0} surfaces. In addition, the results indicate that the adsorbed surfactant layer behaves as a permeable mask, partially slowing down the etch rate of the affected surface orientation/s and thus enforcing their appearance on the etching front. The peculiar etching properties of surfactant-added and surfactant-free TMAH are then utilized for the fabrication of advanced micromechanical structures with new shapes on Si{1 0 0} wafers and polydimethylsiloxane based on complex Si{1 0 0} molds.

  17. Metal ion coordination, conditional stability constants, and solution behavior of chelating surfactant metal complexes.

    Science.gov (United States)

    Svanedal, Ida; Boija, Susanne; Almesåker, Ann; Persson, Gerd; Andersson, Fredrik; Hedenström, Erik; Bylund, Dan; Norgren, Magnus; Edlund, Håkan

    2014-04-29

    Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu(2+) ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu(2+) ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory.

  18. Selection and evaluation of adsorbents for the removal of anionic surfactants from laundry rinsing water.

    Science.gov (United States)

    Schouten, Natasja; van der Ham, Louis G J; Euverink, Gert-Jan W; de Haan, André B

    2007-10-01

    Low-cost adsorbents were tested to remove anionic surfactants from laundry rinsing water to allow re-use of water. Adsorbents were selected corresponding to the different surfactant adsorption mechanisms. Equilibrium adsorption studies of linear alkyl benzene sulfonate (LAS) show that ionic interaction results in a high maximum adsorption capacity on positively charged adsorbents of 0.6-1.7 gLAS/g. Non-ionic interactions, such as hydrophobic interactions of LAS with non-ionic resins or activated carbons, result in a lower adsorption capacity of 0.02-0.6 gLAS/g. Negatively charged materials, such as cation exchange resins or bentonite clay, have negligible adsorption capacities for LAS. Similar results are obtained for alpha olefin sulfonate (AOS). Cost comparison of different adsorbents shows that an inorganic anion exchange material (layered double hydroxide) and activated carbons are the most cost-effective materials in terms of the amount of surfactant adsorbed per dollar worth of adsorbent.

  19. 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.

  20. Adsorption and desorption of cationic surfactants onto silica from toluene studied by ATR-FTIR.

    Science.gov (United States)

    Tabor, Rico F; Eastoe, Julian; Dowding, Peter

    2010-01-19

    The adsorption and desorption behavior of cationic dialkyldimethylammonium bromide surfactants (Di-CnDABs where n = 10, 12, 14) at the silica-toluene interface has been studied. Adsorption is a rapid process, consistent with transport control, whereas desorption appears to occur in a two-stage process, with varying proportions of surfactant desorbing in fast and slow modes. These proportions appear to be affected by trace moisture present in the adjacent toluene solvent, possibly owing to competition between surfactant and water molecules for surface sites. Surprisingly, the surfactant tail length (n) has a significant impact on solubility in toluene, and this appears to affect bulk-surface partitioning. The results are compared with previous experiments utilizing nonionic surfactants (Tabor, R. F.; Eastoe, J.; Dowding, P. Langmuir 2009, 25, 9785), and also with work on surfactant-stabilized silica in nonpolar solvents (Tabor, R. F.; Eastoe, J.; Dowding, P. J.; Grillo, I.; Heenan, R. K.; Hollamby, M. Langmuir 2008, 24, 12793). Observations are explained in terms of the balance of interactions between the surfactant, solvent, and surface.

  1. 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.

  2. Effect of Different Surfactants on the Interfacial Behavior of the n-Hexane-Water System in the Presence of Silica Nanoparticles.

    Science.gov (United States)

    Biswal, Nihar Ranjan; Rangera, Naveen; Singh, Jayant K

    2016-07-28

    This paper presents the effect of negatively charged silica nanoparticles (NPs) on the interfacial tension of the n-hexane-water system at variable concentrations of four different surfactants, viz., an anionic surfactant, sodium dodecyl sulfate (SDS), a cationic surfactant, cetyltrimethylammonium bromide (CTAB), and two nonionic surfactants, Tween 20 and Triton X-100 (TX-100). The presence of negatively charged silica nanoparticles is found to have a different effect depending on the type of surfactant. In the case of ionic surfactants, SDS and CTAB, silica NPs reduce the interfacial tension of the system. On the contrary, for nonionic surfactants, Tween 20 and TX-100, silica NPs increase the interfacial tension. The increasing/decreasing nature of the interfacial tension in the presence of NPs is well supported by the calculated surface excess concentrations. The diffusion kinetic control (DKC) and statistical rate theory (SRT) models are used to understand the behavior of dynamic interfacial tension of the surfactant-NP-oil-water system. The DKC model is found to describe the studied surfactant-NP-oil-water systems more aptly.

  3. Alkyl propoxy ethoxylate "graded" surfactants: micelle formation and structure in aqueous solutions.

    Science.gov (United States)

    Sarkar, Biswajit; Alexandridis, Paschalis

    2010-04-08

    The self-assembly of alkyl propoxy ethoxylate surfactants in aqueous solutions has been investigated with a focus on the (i) thermodynamics of micellization (critical micellization concentration; free energy, enthalpy, and entropy of micellization) and (ii) structure of the micelles (overall shape and size; local environment in the micelle core and corona) as affected by the surfactant composition (variation of degree of ethoxylation). The various results are compared to those for alkyl ethoxylate and poly(ethylene oxide)-b-poly(propylene oxide) amphiphiles with the aim to elucidate the role of the middle, propoxy, block in the novel alkyl propoxy ethoxylate surfactants which exhibit a "graded" hydrophobic-hydrophilic character.

  4. Nanofiltration: ion exchange system for effective surfactant removal from water solutions

    Directory of Open Access Journals (Sweden)

    I. Kowalska

    2014-12-01

    Full Text Available A system combining nanofiltration and ion exchange for highly effective separation of anionic surfactant from water solutions was proposed. The subjects of the study were nanofiltration polyethersulfone membranes and ion-exchange resins differing in type and structure. The quality of the treated solution was affected by numerous parameters, such as quality of the feed solution, membrane cut-off, resin type, dose and the solution contact time with the resin. A properly designed purification system made it possible to reduce the concentration of anionic surfactant below 1 mg L-1 from feed solutions containing surfactant in concentrations above the CMC value.

  5. 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.

  6. Interactions of Ovalbumin with Ionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    GUO Xia; YAN Hui; GUO Rong

    2008-01-01

    The interactions of ovalbumin (OVA) with one anionic surfactant,sodium dodecyl sulfate (SDS),and two cationic surfactants,dodecyl trimethylammonium bromide (DTAB) and cetyl trimethylammonium bromide (CTAB),in water have been studied through fluorescence and UV-Vis spectroscopies and transmission electronic microscopy,combined with the measurement of conductivity.OVA can increase the critical micelle concentrations (cmc) of SDS and CTAB but has little effect on that of DTAB.The interaction between surfactant monomer and OVA is greater than that between surfactant micelles and OVA.Moreover,SDS can make OVA unfolded while cationic surfactants cannot.

  7. Surfactant-free Preparation of Highly Stable Zwitterionic Poly(amido amine) Nanogels with Minimal Cytotoxicity

    NARCIS (Netherlands)

    Ekkelenkamp, A.E.; Jansman, M.M.T.; Roelofs-Haarhuis, H.M.; Engbersen, J.F.J.; Paulusse, J.M.J.

    2016-01-01

    Narrowly dispersed zwitterionic poly(amido amine) (PAA) nanogels with a diameter of approximately 100 nm were prepared by a high-yielding and surfactant-free, inverse nanoprecipitation of PAA polymers. The resulting, negatively charged, nanogels (PAA-NG1) were functionalized with N,N-dimethylethylen

  8. The Weak Interaction of Surfactants with Polymer Brushes and Its Impact on Lubricating Behavior

    NARCIS (Netherlands)

    Zhang, Ran; Ma, Shuanhong; Wei, Qiangbing; Ye, Qian; Yu, Bo; Gucht, Van Der Jasper; Zhou, Feng

    2015-01-01

    We study the weak interaction between polymers and oppositely charged surfactants and its effect on the lubricating behavior and wettability of polymer brush-covered surfaces. For cationic (PMETAC) and anionic (PSPMA) brushes, a gradual transition from ultralow friction to ultrahigh friction was

  9. Excitation energy transfer and charge separation are affected in Arabidopsis thaliana mutants lacking light-harvesting chlorophyll a/b binding protein Lhcb3.

    Science.gov (United States)

    Adamiec, Małgorzata; Gibasiewicz, Krzysztof; Luciński, Robert; Giera, Wojciech; Chełminiak, Przemysław; Szewczyk, Sebastian; Sipińska, Weronika; van Grondelle, Rienk; Jackowski, Grzegorz

    2015-12-01

    The composition of LHCII trimers as well as excitation energy transfer and charge separation in grana cores of Arabidopsis thaliana mutant lacking chlorophyll a/b binding protein Lhcb3 have been investigated and compared to those in wild-type plants. In grana cores of lhcb3 plants we observed increased amounts of Lhcb1 and Lhcb2 apoproteins per PSII core. The additional copies of Lhcb1 and Lhcb2 are expected to substitute for Lhcb3 in LHCII trimers M as well as in the LHCII "extra" pool, which was found to be modestly enlarged as a result of the absence of Lhcb3. Time-resolved fluorescence measurements reveal a deceleration of the fast phase of excitation dynamics in grana cores of the mutant by ~15 ps, whereas the average fluorescence lifetime is not significantly altered. Monte Carlo modeling predicts a slowing down of the mean hopping time and an increased stabilization of the primary charge separation in the mutant. Thus our data imply that absence of apoprotein Lhcb3 results in detectable differences in excitation energy transfer and charge separation.

  10. Solubilization and separation of p-tert-butylphenol using polyelectrolyte/surfactant complexes in colloid-enhanced ultrafiltration

    Energy Technology Data Exchange (ETDEWEB)

    Uchiyama, Hirotaka; Christian, S.D.; Tucker, E.E.; Scamehorn, J.F. (Univ. of Oklahoma, Norman, OK (United States))

    1994-03-15

    Water-soluble polyelectrolyte/surfactant complexes, involving oppositely charged species, can form at quite low thermodynamic activities of the surfactant. This fact can be exploited in colloid-enhanced ultrafiltration separations, where both molecular organic pollutants and toxic ions are to be removed from contaminated aqueous streams. Investigations have been made of (a) the solubilization and ultrafiltration of solutions of organic solutes in polymer/surfactant solutions, for comparison with studies of micellar surfactant solutions in the absence of added polymers; (b) the penetration of surfactant through the membrane (leakage of monomer) in dialysis and ultrafiltration experiments; and (c) the utility of polyelectrolytes as scavengers'' for surfactant species that-enter the permeate or filtrate in colloid-enhanced ultrafiltration separations. The polyelectrolyte chosen for the studies is sodium poly(styrenesulfonate) and the surfactant is cetylpyridinium chloride (hexadecylpyridinium chloride). A detailed study has been made of the solubilization and separation of p-tert-butylphenol in aqueous mixtures of sodium poly(styrenesulfonate) and cetylpyridinium chloride, at polyelectrolyte to surfactant mole ratios of two to one and three to one.

  11. Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

    Directory of Open Access Journals (Sweden)

    Mahdi ES

    2011-06-01

    Full Text Available Elrashid Saleh Mahdi1, Mohamed HF Sakeena1, Muthanna F Abdulkarim1, Ghassan Z Abdullah1,3, Munavvar Abdul Sattar2, Azmin Mohd Noor11Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia; 3Department of Pharmaceutical Technology, International Medical University, Bukit Jalil, Kuala Lumpur, MalaysiaBackground: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature.Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters.Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant

  12. Photocatalytic Degradation of Diethyl Phthalate with Surfactant Addition

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tianyong; HU Juan; ZHANG Youlan; LI Bin; FEI Xuening

    2006-01-01

    This paper studies the adsorption of diethyl phthalate (DEP,an environmental hormone) on the surface of nanoscale TiO2, effects of pH value of solutions, initial concentrations of DEP and additive surfactant on photocatalytic degradation and dynamics of DEP. Under ultra violet illumination, the interaction between DEP and surfactants including DBS (sodium dodecylbenzenesulfonate), CTAB (cetyltrimethylammonium bromide), and OP-10 (nonylphenol polyoxyethylene ether)was exploited from the perspective of degradation speed calculated by the data of high pressure liquid chromatography (HPLC) and UV-Vis spectra, respectively. Photocatalytic degradation of DEP followed pseudo first-order reaction kinetics. DEP as substrate degraded fast when its initial concentration was 130 mg/L. TiO2 had certain adsorption ability of DEP. TiO2 could adsorb the most DEP at the approximately neutral pH of 6.91. Degradation of DEP was not affected obviously by ad ditives OP-10 and JBS. Degradation rate of DEP was not enhanced greatly in the presence of surfactants, but degradation of DBS was sped up. Degradation rate of DEP was depressed in the presence of additive CTAB. The more CTAB was added, the less DEP was degraded. Degradation rate of CTAB became slow with the increase of initial CTAB concentration. The possible adsorption models among TiO2, DEP and surfactants were given.

  13. Colloidal particles derived from a complex of phosphotungstic Acid and ethoxylated surfactants.

    Science.gov (United States)

    Sweeney, Maura A; Smith, Thomas W; Croucher, Melvin; Langner, Andreas; Miri, Massoud; Klymachyov, Alex; Kaplan, Sam; Tshudy, Dwight

    2002-09-01

    Stable, colloidal sols of submicron size were prepared by titration of aqueous solutions of alkylene oxide surfactants with phosphotungstic acid, H(3)PW(12)O(40) (PTA), followed by neutralization with ammonium or potassium hydroxide. The stoichiometry of the complex between phosphotungstic acid and the ethoxylated surfactant was determined by (1)H and (31)P NMR and was dependent upon the degree of ethoxylation. For example, in the ethoxylated octylphenol having 9-10 ethylene oxide units, Triton X-100, the mole ratio of surfactant to PTA was 4.5. In the ethoxylated octylphenol having 70 ethylene oxide units, Triton X-705, the mole ratio of surfactant to PTA was 1. Prior to nucleation of particles, phosphotungstic acid forms an apparent yellow charge transfer complex with ethoxylated alkylphenol surfactants, typified by Triton X-405. This complex is characterized by an absorption spectrum that is the sum of the spectra of Triton X-405 and PTA with a very weak shoulder at 400-500 nm. Particles were nearly monodisperse and their size was dependent on the nonionic surfactant employed, the heteropolyacid, and the rate of addition of heteropolyacid solution.

  14. Physicochemical properties of nanoparticles regulate translocation across pulmonary surfactant monolayer and formation of lipoprotein corona.

    Science.gov (United States)

    Hu, Guoqing; Jiao, Bao; Shi, Xinghua; Valle, Russell P; Fan, Qihui; Zuo, Yi Y

    2013-12-23

    Interaction with the pulmonary surfactant film, being the first line of host defense, represents the initial bio-nano interaction in the lungs. Such interaction determines the fate of the inhaled nanoparticles and their potential therapeutic or toxicological effect. Despite considerable progress in optimizing physicochemical properties of nanoparticles for improved delivery and targeting, the mechanisms by which inhaled nanoparticles interact with the pulmonary surfactant film are still largely unknown. Here, using combined in vitro and in silico methods, we show how hydrophobicity and surface charge of nanoparticles differentially regulate the translocation and interaction with the pulmonary surfactant film. While hydrophilic nanoparticles generally translocate quickly across the pulmonary surfactant film, a significant portion of hydrophobic nanoparticles are trapped by the surfactant film and encapsulated in lipid protrusions upon film compression. Our results support a novel model of pulmonary surfactant lipoprotein corona associated with inhaled nanoparticles of different physicochemical properties. Our data suggest that the study of pulmonary nanotoxicology and nanoparticle-based pulmonary drug delivery should consider this lipoprotein corona.

  15. Interaction of Sodium Hyaluronate with a Biocompatible Cationic Surfactant from Lysine: A Binding Study.

    Science.gov (United States)

    Bračič, Matej; Hansson, Per; Pérez, Lourdes; Zemljič, Lidija F; Kogej, Ksenija

    2015-11-10

    Mixtures of natural and biodegradable surfactants and ionic polysaccharides have attracted considerable research interest in recent years because they prosper as antimicrobial materials for medical applications. In the present work, interactions between the lysine-derived biocompatible cationic surfactant N(ε)-myristoyl-lysine methyl ester, abbreviated as MKM, and the sodium salt of hyaluronic acid (NaHA) are investigated in aqueous media by potentiometric titrations using the surfactant-sensitive electrode and pyrene-based fluorescence spectroscopy. The critical micelle concentration in pure surfactant solutions and the critical association concentration in the presence of NaHA are determined based on their dependence on the added electrolyte (NaCl) concentration. The equilibrium between the protonated (charged) and deprotonated (neutral) forms of MKM is proposed to explain the anomalous binding isotherms observed in the presence of the polyelectrolyte. The explanation is supported by theoretical model calculations of the mixed-micelle equilibrium and the competitive binding of the two MKM forms to the surface of the electrode membrane. It is suggested that the presence of even small amounts of the deprotonated form can strongly influence the measured electrode response. Such ionic-nonionic surfactant mixtures are a special case of mixed surfactant systems where the amount of the nonionic component cannot be varied independently as was the case for some of the earlier studies.

  16. On relationships between surfactant type and globular proteins interactions in solution.

    Science.gov (United States)

    Blanco, Elena; Ruso, Juan M; Prieto, Gerardo; Sarmiento, Félix

    2007-12-01

    The binding of sodium perfluorooctanoate (C8FONa), sodium octanoate (C8HONa), lithium perfluorooctanoate (C8FOLi), and sodium dodecanoate (C12HONa) onto myoglobin, ovalbumin, and catalase in water has been characterized using electrophoretic mobility. The tendency of the protein-surfactant complexes to change their charge in the order catalase < ovalbumin < myoglobin was observed which was related to the contents of alpha-helices in the proteins. alpha-Helices are more hydrophobic than beta-sheets. The effect of surfactant on the zeta potentials follows C8HONa < C8FONa < C8FOLi < C12HONa for catalase and ovalbumin; and C8HONa < C8FOLi < C8FONa < C12HONa for myoglobin. The numbers of binding sites on the proteins were determined from the observed increases of the zeta-potential as a function of surfactant concentration in the regions where the binding was a consequence of the hydrophobic effect. The Gibbs energies of binding of the surfactants onto the proteins were evaluated. For all systems, Gibbs energies are negative and large at low concentrations (where binding to the high energy sites takes place) and become less negative at higher ones. This fact suggests a saturation process. Changes in Gibbs energies with the different proteins and surfactants under study have been found to follow same sequence than that found for the charge. The role of hydrophobic interactions in these systems has been demonstrated to be the predominant.

  17. 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.

  18. Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

    Directory of Open Access Journals (Sweden)

    Sagarika Mohanty

    2013-01-01

    Full Text Available Surfactant enhanced bioremediation (SEB of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs. Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review.

  19. 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

  20. Synthesis and properties of differently charged chemiluminescent acridinium ester labels.

    Science.gov (United States)

    Natrajan, Anand; Sharpe, David

    2013-02-14

    Chemiluminescent acridinium dimethylphenyl esters containing N-sulfopropyl groups in the acridinium ring are highly sensitive, hydrophilic labels that are used in automated immunoassays for clinical diagnostics. Light emission from these labels is triggered with alkaline peroxide in the presence of a cationic surfactant. At physiological pH, N-sulfopropyl acridinium esters exist as water adducts that are commonly referred to as pseudobases. Pseudobase formation, which results from addition of water to the zwitterionic N-sulfopropyl acridinium ring, neutralizes the positive charge on the acridinium nitrogen and imparts a net negative charge to the label due to the sulfonate moiety. As a consequence, N-sulfopropyl acridinium ester conjugates of small molecule haptens as well as large molecules such as proteins gain negative charges at neutral pH. In the current study, we describe the synthesis and properties of two new hydrophilic acridinium dimethylphenyl ester labels where the net charge in the labels was altered. In one label, the structure of the hydrophilic N-alkyl group attached to the acridinium ring was changed so that the pseudobase of the label contains no net charge. In the second acridinium ester, two additional negative charges in the form of sulfopropyl groups were added to the acridinium ring to make this label's pseudobase strongly anionic. Chemiluminescence measurements of these labels, as well as their conjugates of an antibody with a neutral pI, indicate that acridinium ester charge while having a modest effect on emission kinetics has little influence on light output. However, our results demonstrate that acridinium ester charge can affect protein pI, apparent chemiluminescence stability and non-specific binding of protein conjugates to microparticles. These results emphasize the need for careful consideration of acridinium ester charge in order to optimize reagent stability and performance in immunoassays. In the current study, we observed that

  1. Anaerobic Biodegradation of Detergent Surfactants

    OpenAIRE

    Erich Jelen; Ute Merrettig-Bruns

    2009-01-01

    Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have str...

  2. 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

  3. Surfactant inhibition in acute respiratory failure : consequences for exogenous surfactant therapy

    NARCIS (Netherlands)

    E.P. Eijking (Eric)

    1993-01-01

    textabstractThe neonatal respiratory distress syndrome (RDS) is characterized by immaturity of the lung, resulting in relative or absolute absence of pulmonary surfactant. Worldwide, neonates suffering from RDS have been treated successfully with exogenous surfactant preparations. Currently, exogeno

  4. Selection and evaluation of adsorbents for the removal of anionic surfactants from laundry rinsing water

    OpenAIRE

    2007-01-01

    Low-cost adsorbents were tested to remove anionic surfactants from laundry rinsing water to allow re-use of water. Adsorbents were selected corresponding to the different surfactant adsorption mechanisms. Equilibrium adsorption studies of linear alkyl benzene sulfonate (LAS) show that ionic interaction results in a high maximum adsorption capacity on positively charged adsorbents of 0.6–1.7 g LAS/g. Non-ionic interactions, such as hydrophobic interactions of LAS with non-ionic resins or activ...

  5. 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.

  6. Remediation using trace element humate surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Riddle, Catherine Lynn; Taylor, Steven Cheney; Bruhn, Debra Fox

    2016-08-30

    A method of remediation at a remediation site having one or more undesirable conditions in which one or more soil characteristics, preferably soil pH and/or elemental concentrations, are measured at a remediation site. A trace element humate surfactant composition is prepared comprising a humate solution, element solution and at least one surfactant. The prepared trace element humate surfactant composition is then dispensed onto the remediation site whereby the trace element humate surfactant composition will reduce the amount of undesirable compounds by promoting growth of native species activity. By promoting native species activity, remediation occurs quickly and environmental impact is minimal.

  7. 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.

  8. Using biologically soft surfactants for dust suppression

    Energy Technology Data Exchange (ETDEWEB)

    Tkachenko, N.G.; Kolodiichak, V.K.; Motrii, A.E.; Severin, V.D.

    1982-07-01

    This article discusses environmental aspects of using surfactants in coal mines for dust suppression. Surfactants for underground black coal mines in the USSR are divided into three classes: so-called soft surfactants with a decomposition period from 1 to 3 days, hard surfactants with decomposition exceeding a month and an intermediary group. The decomposition process is analyzed; the role played by fermentation is stressed. Environmental effects of surfactant decomposition are evaluated. Selected surfactants tested in Soviet laboratories are described. The results of experimental use of diethanolamide as a surfactant for water injection in coal seams are evaluated. Wetting time amounts to 1 s when a 0.2% concentration is used. When surfactant concentration in water is reduced to 0.05% wetting time does not change; when concentration decreases to 0.025% wetting time increases to 3 s. Surfactant efficiency is investigated under operational conditions in a Donbass mine. Specifications of the working face, mining system and air pollution caused by a shearer loader are discussed. When diethanolamide is used dust suppression efficiency ranges from 86.4 to 90.4%. During the tests diethanolamide concentration in water was 0.05%.

  9. Biophysical inhibition of pulmonary surfactant function by polymeric nanoparticles: role of surfactant protein B and C.

    Science.gov (United States)

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

    2014-11-01

    The current study investigated the mechanisms involved in the process of biophysical inhibition of pulmonary surfactant by polymeric nanoparticles (NP). The minimal surface tension of diverse synthetic surfactants was monitored in the presence of bare and surface-decorated (i.e. poloxamer 407) sub-100 nm poly(lactide) NP. Moreover, the influence of NP on surfactant composition (i.e. surfactant protein (SP) content) was studied. Dose-elevations of SP advanced the biophysical activity of the tested surfactant preparation. Surfactant-associated protein C supplemented phospholipid mixtures (PLM-C) were shown to be more susceptible to biophysical inactivation by bare NP than phospholipid mixture supplemented with surfactant protein B (PLM-B) and PLM-B/C. Surfactant function was hindered owing to a drastic depletion of the SP content upon contact with bare NP. By contrast, surface-modified NP were capable of circumventing unwanted surfactant inhibition. Surfactant constitution influences the extent of biophysical inhibition by polymeric NP. Steric shielding of the NP surface minimizes unwanted NP-surfactant interactions, which represents an option for the development of surfactant-compatible nanomedicines.

  10. 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 distri

  11. Electrically charged targets

    Science.gov (United States)

    Goodman, Ronald K.; Hunt, Angus L.

    1984-01-01

    Electrically chargeable laser targets and method for forming such charged targets in order to improve their guidance along a predetermined desired trajectory. This is accomplished by the incorporation of a small amount of an additive to the target material which will increase the electrical conductivity thereof, and thereby enhance the charge placed upon the target material for guidance thereof by electrostatic or magnetic steering mechanisms, without adversely affecting the target when illuminated by laser energy.

  12. Surfactant-assisted dispersion of carbon nanotubes: mechanism of stabilization and biocompatibility of the surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Raman Preet, E-mail: ramanpreetsingh@hotmail.com [Evalueserve SEZ (Gurgaon) Pvt. Ltd. (India); Jain, Sanyog [National Institute of Pharmaceutical Education and Research, Centre for Pharmaceutical Nanotechnology, Department of Pharmaceutics (India); Ramarao, Poduri, E-mail: ramaraop@yahoo.com [Central University of Punjab, School of Basic and Applied Sciences (India)

    2013-10-15

    Nanoparticles (NPs) are thermodynamically unstable system and tend to aggregate to reduce free energy. The aggregation property of NPs results in inhomogeneous exposure of cells to NPs resulting in variable cellular responses. Several types of surfactants are used to stabilize NP dispersions and obtain homogenous dispersions. However, the effects of these surfactants, per se, on cellular responses are not completely known. The present study investigated the application of Pluronic F68 (PF68) for obtaining stable dispersion of NPs using carbon nanotubes as model NPs. PF68-stabilized NP suspensions are stable for long durations and do not show signs of aggregation or settling during storage or after autoclaving. The polyethylene oxide blocks in PF68 provide steric hindrance between adjacent NPs leading to stable NP dispersions. Further, PF68 is biocompatible in nature and does not affect integrity of mitochondria, lysosomes, DNA, and nuclei. Also, PF68 neither induce free radical or cytokine production nor does it interfere with cellular uptake mechanisms. The results of the present study suggest that PF68-assisted dispersion of NPs produced suspensions, which are stable after autoclaving. Further, PF68 does not interfere with normal physiological functions suggesting its application in nanomedicine and nanotoxicity evaluation.

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

    Energy Technology Data Exchange (ETDEWEB)

    García Daza, Fabián A.; Mackie, Allan D., E-mail: allan.mackie@urv.cat [Department d’Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Avinguda dels Països Catalans 26, 43007 Tarragona (Spain); Colville, Alexander J. [Department of Chemical Engineering, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115-5000 (United States)

    2015-03-21

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

  14. Migration of a surfactant-laden droplet in non-isothermal Poiseuille flow

    Science.gov (United States)

    Das, Sayan; Mandal, Shubhadeep; Som, S. K.; Chakraborty, Suman

    2017-01-01

    The motion of a surfactant-laden viscous droplet in the presence of non-isothermal Poiseuille flow is studied analytically and numerically. Specifically, the focus of the present study is on the role of interfacial Marangoni stress generated due to imposed temperature gradient and non-uniform distribution of bulk-insoluble surfactants towards dictating the velocity and direction of motion of the droplet when the background flow is Poiseuille. Assuming the thermal convection and fluid inertia to be negligible, we obtain the explicit expression for steady velocity of a non-deformable spherical droplet when the droplet is located at the centerline of the imposed unbounded Poiseuille flow and encountering a linearly varying temperature field. Under these assumptions, the interfacial transport of surfactants is governed by the surface Péclet number which represents the relative strength of the advective transport of surfactant molecules over the diffusive transport. We obtain analytical solution for small and large values of the surface Péclet number. Analytical solution is also obtained for the case in which the surface Péclet number is of order unity by considering small surfactant Marangoni number which represents the relative strength of the surfactant-induced Marangoni stress over the viscous stress. For an arbitrary surface Péclet number, a numerical solution of the surfactant transport equation is performed using an iterative method which compares well with the analytical solutions. Depending on the direction of temperature gradient with respect to the imposed Poiseuille flow, the surfactant-induced Marangoni stress affects the droplet velocity significantly. When the imposed temperature increases in the direction of imposed Poiseuille flow, surfactants retard the droplet motion as compared with a surfactant-free droplet. However, when the imposed temperature decreases in the direction of imposed Poiseuille flow, the presence of surfactants may increase or

  15. A new nano-engineered hierarchical membrane for concurrent removal of surfactant and oil from oil-in-water nanoemulsion

    Science.gov (United States)

    Qin, Detao; Liu, Zhaoyang; Bai, Hongwei; Sun, Darren Delai; Song, Xiaoxiao

    2016-04-01

    Surfactant stabilized oil-in-water nanoemulsions pose a severe threat to both the environment and human health. Recent development of membrane filtration technology has enabled efficient oil removal from oil/water nanoemulsion, however, the concurrent removal of surfactant and oil remains unsolved because the existing filtration membranes still suffer from low surfactant removal rate and serious surfactant-induced fouling issue. In this study, to realize the concurrent removal of surfactant and oil from nanoemulsion, a novel hierarchically-structured membrane is designed with a nanostructured selective layer on top of a microstructured support layer. The physical and chemical properties of the overall membrane, including wettability, surface roughness, electric charge, thickness and structures, are delicately tailored through a nano-engineered fabrication process, that is, graphene oxide (GO) nanosheet assisted phase inversion coupled with surface functionalization. Compared with the membrane fabricated by conventional phase inversion, this novel membrane has four times higher water flux, significantly higher rejections of both oil (~99.9%) and surfactant (as high as 93.5%), and two thirds lower fouling ratio when treating surfactant stabilized oil-in-water nanoemulsion. Due to its excellent performances and facile fabrication process, this nano-engineered membrane is expected to have wide practical applications in the oil/water separation fields of environmental protection and water purification.

  16. Porous gold nanobelts templated by metal-surfactant complex nanobelts.

    Science.gov (United States)

    Li, Lianshan; Wang, Zhijian; Huang, Teng; Xie, Jinglin; Qi, Limin

    2010-07-20

    Unique, porous gold nanobelts consisting of self-organized nanoparticles were synthesized in a high yield by morphology-preserved transformation from metal-surfactant complex precursor nanobelts formed by a bolaform surfactant dodecane-1,12-bis(trimethylammonium bromide) (N-C(12)-NBr(2)) and HAuCl(4). It was revealed that the precursor nanobelts of the stoichiometric N-C(12)-N(AuCl(4))(2) complex formed through electrostatic combination of the positively charged quaternary ammonium headgroups of N-C(n)-NBr(2) and the negatively charged AuCl(4)(-) ions. They were subsequently converted into porous gold nanobelts with shrunken sizes upon reduction by NaBH(4). The morphology of the produced gold nanostructures could be adjusted by changing the mixing ratio between N-C(12)-NBr(2) and HAuCl(4) in the reaction solution. It was found that the obtained porous Au nanobelts exhibited enhanced catalytic activity toward reduction of 4-nitrophenol compared with solid gold nanobelts, probably owing to their larger surface area and more active sites.

  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.

  18. Structured fluids polymers, colloids, surfactants

    CERN Document Server

    Witten, Thomas A

    2010-01-01

    Over the last thirty years, the study of liquids containing polymers, surfactants, or colloidal particles has developed from a loose assembly of facts into a coherent discipline with substantial predictive power. These liquids expand our conception of what condensed matter can do. Such structured-fluid phenomena dominate the physical environment within living cells. This book teaches how to think of these fluids from a unified point of view showing the far-reaching effects ofthermal fluctuations in producing forces and motions. Keeping mathematics to a minimum, the book seeks the simplest expl

  19. Innovation in surfactant therapy I: surfactant lavage and surfactant administration by fluid bolus using minimally invasive techniques.

    Science.gov (United States)

    Dargaville, Peter A

    2012-01-01

    Innovation in the field of exogenous surfactant therapy continues more than two decades after the drug became commercially available. One such innovation, lung lavage using dilute surfactant, has been investigated in both laboratory and clinical settings as a treatment for meconium aspiration syndrome (MAS). Studies in animal models of MAS have affirmed that dilute surfactant lavage can remove meconium from the lung, with resultant improvement in lung function. In human infants both non-randomised studies and two randomised controlled trials have demonstrated a potential benefit of dilute surfactant lavage over standard care. The largest clinical trial, performed by our research group in infants with severe MAS, found that lung lavage using two 15-ml/kg aliquots of dilute surfactant did not reduce the duration of respiratory support, but did appear to reduce the composite outcome of death or need for extracorporeal membrane oxygenation. A further trial of lavage therapy is planned to more precisely define the effect on survival. Innovative approaches to surfactant therapy have also extended to the preterm infant, for whom the more widespread use of continuous positive airway pressure (CPAP) has meant delaying or avoiding administration of surfactant. In an effort to circumvent this problem, less invasive techniques of bolus surfactant therapy have been trialled, including instillation directly into the pharynx, via laryngeal mask and via brief tracheal catheterisation. In a recent clinical trial, instillation of surfactant into the trachea using a flexible feeding tube was found to reduce the need for subsequent intubation. We have developed an alternative method of brief tracheal catheterisation in which surfactant is delivered via a semi-rigid vascular catheter inserted through the vocal cords under direct vision. In studies to date, this technique has been relatively easy to perform, and resulted in rapid improvement in lung function and reduced need for

  20. Sequential adsorption of an irreversibly adsorbed nonionic surfactant and an anionic surfactant at an oil/aqueous interface.

    Science.gov (United States)

    Kirby, Stephanie M; Anna, Shelley L; Walker, Lynn M

    2015-04-14

    Aerosol-OT (AOT) and Tween 80 are two of the main surfactants in commercial dispersants used in response to oil spills. Understanding how multicomponent surfactant systems interact at oil/aqueous interfaces is crucial for improving both dispersant design and application efficacy. This is true of many multicomponent formulations; a lack of understanding of competition for the oil/water interface hinders formulation optimization. In this study, we have characterized the sequential adsorption behavior of AOT on squalane/aqueous interfaces that have been precoated with Tween 80. A microtensiometer is used to measure the dynamic interfacial tension of the system. Tween 80 either partially or completely irreversibly adsorbs to squalane/aqueous interfaces when rinsed with deionized water. These Tween 80 coated interfaces are then exposed to AOT. AOT adsorption increases with AOT concentration for all Tween 80 coverages, and the resulting steady-state interfacial tension values are interpreted using a Langmuir isotherm model. In the presence of 0.5 M NaCl, AOT adsorption significantly increases due to counterion charge screening of the negatively charged head groups. The presence of Tween 80 on the interface inhibits AOT adsorption, reducing the maximum surface coverage as compared to a clean interface. Tween 80 persists on the interface even after exposure to high concentrations of AOT.

  1. Second Law Analysis of Adiabatic and Non-Adiabatic Pipeline Flows of Unstable and Surfactant-Stabilized Emulsions

    Directory of Open Access Journals (Sweden)

    Rajinder Pal

    2016-03-01

    Full Text Available Entropy generation, and hence exergy destruction, in adiabatic flow of unstable and surfactant-stabilized emulsions was investigated experimentally in different diameter pipes. Four types of emulsion systems are investigated covering a broad range of the dispersed-phase concentration: (a unstable oil-in-water (O/W emulsions without surfactant; (b surfactant-stabilized O/W emulsions; (c unstable water-in-oil (W/O emulsions without surfactant; and (d surfactant-stabilized W/O emulsions. The entropy generation rate per unit pipe length is affected by the type of the emulsion as well as its stability. Unstable emulsions without any surfactant present at the interface generate less entropy in the turbulent regime as compared with the surfactant-stabilized emulsions of the same viscosity and density. The effect of surfactant is particularly severe in the case of W/O emulsions. In the turbulent regime, the rate of entropy generation in unstable W/O emulsions is much lower in comparison with that observed in the stable W/O emulsions. A significant delay in the transition from laminar to turbulent regime is also observed in the case of unstable W/O emulsion. Finally, the analysis and simulation results are presented on non-adiabatic pipeline flow of emulsions.

  2. 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…

  3. 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...

  4. Enthalpy of interaction and binding isotherms of non-ionic surfactants onto micellar amphiphilic polymers (amphipols).

    Science.gov (United States)

    Diab, C; Winnik, F M; Tribet, C

    2007-03-13

    The interactions in water between short amphiphilic macromomolecules, known as amphipols, and three neutral surfactants (detergents), dodecylmaltoside (DM), n-octylthioglucoside (OTG), and n-octyltetraethyleneoxide (C8E4), have been assessed by static and dynamic light-scattering (SLS and DLS), capillary electrophoresis (CE), and isothermal titration calorimetry (ITC). The amphipols selected are random copolymers of the hydrophobic n-octylacrylamide (25-30 mol %), a charged hydrophilic monomer, either acrylic acid ( approximately 35 mol %) or a phosphorylcholine-modified acrylamide (40-70 mol %), and, optionally, N-isopropylacrylamide (30-40 mol %). In water, the copolymers form micelles of small size (hydrodynamic radius: approximately 5 nm). Neutral surfactants, below their critical micellar concentration (cmc), form mixed micelles with the amphipols irrespective of the chemical structure of the detergent or the polymer. The fraction of detergent in the surfactant/polymer complexes increases significantly (cooperatively) as the surfactant concentration nears the cmc. The ITC data, together with data gathered by CE, were fitted via a regular mixing model, which allowed us to predict the detergent concentration in equilibrium with complexes and the heat evolved upon transfer of detergent from water into a mixed surfactant/polymer complex. The enthalpy of transfer was found to be almost equal to the enthalpy of micellization, and the regular mixing model points to a near-ideal mixing behavior for all systems. Amphipols are promising tools in biochemistry where they are used, together with neutral surfactants, for the stabilization and handling of proteins. This study provides guidelines for the optimization of current protein purification protocols and for the formulations of surfactant/polymer systems used in pharmaceutics, cosmetics, and foodstuffs.

  5. 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

  6. Metathesis depolymerization for removable surfactant templates.

    Energy Technology Data Exchange (ETDEWEB)

    Zifer, Thomas (Sandia National Laboratories, Livermore, CA); Wheeler, David Roger; Rahimian, Kamayar; McElhanon, James Ross (Sandia National Laboratories, Livermore, CA); Long, Timothy Michael; Jamison, Gregory Marks; Loy, Douglas Anson (Los Alamos National Laboratories, Los Alamos, NM); Kline, Steven R. (National Institute of Standards and Technology, Gaithersburg, MD); Simmons, Blake Alexander (Sandia National Laboratories, Livermore, CA)

    2005-03-01

    Current methodologies for the production of meso- and nanoporous materials include the use of a surfactant to produce a self-assembled template around which the material is formed. However, post-production surfactant removal often requires centrifugation, calcination, and/or solvent washing which can damage the initially formed material architecture(s). Surfactants that can be disassembled into easily removable fragments following material preparation would minimize processing damage to the material structure, facilitating formation of templated hybrid architectures. Herein, we describe the design and synthesis of novel cationic and anionic surfactants with regularly spaced unsaturation in their hydrophobic hydrocarbon tails and the first application of ring closing metathesis depolymerization to surfactant degradation resulting in the mild, facile decomposition of these new compounds to produce relatively volatile nonsurface active remnants.

  7. Enhanced Oil Recovery with Surfactant Flooding

    DEFF Research Database (Denmark)

    Sandersen, Sara Bülow

    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...... observation of the phase behavior of the different systems at various temperatures and pressures inside the high pressure cell. Phase volumes can also be measured visually through the glass window using precision equipment. The surfactant system for which an experimental study was carried out consisted...... models, such as equations of state, while able to predict and correlate phase equilibrium in two liquid phases (with varying degrees of success) cannot account for the formation of a microemulsion phase. The presence of electrolytes in the surfactant systems further complicates the problem...

  8. Ion-exchange and hydrophobic interactions affecting selectivity for neutral and charged solutes on three structurally similar agglomerated ion-exchange and mixed-mode stationary phases.

    Science.gov (United States)

    Kazarian, Artaches A; Taylor, Mark R; Haddad, Paul R; Nesterenko, Pavel N; Paull, Brett

    2013-11-25

    The nature and extent of mixed-mode retention mechanisms evident for three structurally related, agglomerated, particle-based stationary phases were evaluated. These three agglomerated phases were Thermo Fisher ScientificIon PacAS11-HC - strong anion exchange, Thermo Fisher Scientific IonPac CS10--strong cation-exchange PS-DVB, and the Thermo Fisher Scientific Acclaim Trinity P1silica-based substrate, which is commercially marketed as a mixed-mode stationary phase. All studied phases can exhibit zwitterionic and hydrophobic properties, which contribute to the retention of charged organic analytes. A systematic approach was devised to investigate the relative ion-exchange capacities and hydrophobicities for each of the three phases, together with the effect of eluent pH upon selectivity, using a specifically selected range of anionic, cationic and neutral aromatic compounds. Investigation of the strong anion-exchange column and the Trinity P1 mixed-mode substrate, in relation to ion-exchange capacity and pH effects, demonstrated similar retention behaviour for both the anionic and ampholytic solutes, as expected from the structurally related phases. Further evaluation revealed that the ion-exchange selectivity of the mixed-mode phase exhibited properties similar to that of the strong anion-exchange column, with secondary cation-exchange selectivity, albeit with medium to high anion-exchange and cation-exchange capacities, allowing selective retention for each of the anionic, cationic and ampholytic solutes. Observed mixed-mode retention upon the examined phases was found to be a sum of anion- and cation-exchange interactions, secondary ion-exchange and hydrophobic interactions, with possible additional hydrogen bonding. Hydrophobic evaluation of the three phases revealed logP values of 0.38-0.48, suggesting low to medium hydrophobicity. These stationary phases were also benchmarked against traditional reversed-phase substrates namely, octadecylsilica YMC-Pac Pro C18

  9. 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.

  10. Small angle neutron scattering study of doxorubicin–surfactant complexes encapsulated in block copolymer micelles

    Indian Academy of Sciences (India)

    Jayita Bhattacharjee; Gunjan Verma; V K Aswal; P A Hassan

    2008-11-01

    Self-assembling behaviour of block copolymers and their ability to evade the immune system through polyethylene oxide stealth makes it an attractive candidate for drug encapsulation. Micelles formed by polyethylene oxide–polypropylene oxide–polyethylene oxide triblock copolymers (PEO–PPO–PEO), pluronic P123, have been employed for encapsulating the anti-cancer drug doxorubicin hydrochloride. 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 the anti-cancer drug into nonpolar solvents such as chloroform is investigated. SANS measurements were performed on pluronic P123 mi-celles in the presence of drug–surfactant complex. No significant changes in the structure of the micelles are observed upon drug encapsulation. This demonstrates that surfactant–drug complexes can be encapsulated in block copolymer micelles without disrupting the structure of aggregates.

  11. Effects of Perfluorocarbons on surfactant exocytosis and membrane properties in isolated alveolar type II cells

    Directory of Open Access Journals (Sweden)

    Ravasio Andrea

    2010-05-01

    Full Text Available Abstract Background Perfluorocarbons (PFC are used to improve gas exchange in diseased lungs. PFC have been shown to affect various cell types. Thus, effects on alveolar type II (ATII cells and surfactant metabolism can be expected, data, however, are controversial. Objective The study was performed to test two hypotheses: (I the effects of PFC on surfactant exocytosis depend on their respective vapor pressures; (II different pathways of surfactant exocytosis are affected differently by PFC. Methods Isolated ATII cells were exposed to two PFC with different vapor pressures and spontaneous surfactant exocytosis was measured. Furthermore, surfactant exocytosis was stimulated by either ATP, PMA or Ionomycin. The effects of PFC on cell morphology, cellular viability, endocytosis, membrane permeability and fluidity were determined. Results The spontaneous exocytosis was reduced by PFC, however, the ATP and PMA stimulated exocytosis was slightly increased by PFC with high vapor pressure. In contrast, Ionomycin-induced exocytosis was decreased by PFC with low vapor pressure. Cellular uptake of FM 1-43 - a marker of membrane integrity - was increased. However, membrane fluidity, endocytosis and viability were not affected by PFC incubation. Conclusions We conclude that PFC effects can be explained by modest, unspecific interactions with the plasma membrane rather than by specific interactions with intracellular targets.

  12. Adsorption Behavior and Mechanisms of Surfactants by Farmland Soils in Northeast China

    Institute of Scientific and Technical Information of China (English)

    CHEN Wei-wei; KANG Chun-li; WANG Ting-ting; LI Yue-ming; ZHANG Ying-xin; WEN Xin; GUO Ping

    2011-01-01

    The adsorption of two nonionic surfactants polyethylene glycol tert-octylphenyl ether Triton X-100 (TX-100), polyoxyethylene lauryl ether(Brij35) and an anionic surfactant sodium dodecyl benzene sulfonate(SDBS) by two soils(S1, S2) of different natures and their respective organic-matter-extracted samples(S3, S4) were investigated. These adsorption isotherms show different adsorption stages of different types of surfactants by soils. The data fitted Langmuir equation very well. The adsorption maximum capacity(Q0) indicates that TX-100 and SDBS were in the sequence of S3>S4>S1>S2 in adsorption, however, Brij35 was in the sequence of S4>S3>S1>S2 in adsorption. And the adsorption amounts of the different surfactants by soils followed the order of TX-1 00>Brij35>SDBS. Meanwhile,the adsorption of the nonionic surfactants TX-100 and Brij35 decreased with the increase of their ethylene oxide(EO) numbers. The results indicate that both soil organic matter and mineral played important roles in the adsorption of suffactants, and the adsorption of the surfactants by soils was affected by the physicochemical properties and structures of the soils and suffactants, especially the mineral type and content of soil.

  13. The significance of recurrent lung opacities in neonates on surfactant treatment for respiratory distress syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Odita, J.C. [Dept. of Radiology, Louisiana State Univ. Health Sciences Center, Shreveport (United States)

    2001-02-01

    Purpose. To determine the significance of recurrent opacities in chest radiographs of neonates on surfactant therapy for respiratory distress syndrome (RDS) after an initial period of improvement. Materials and methods. Serial pre- and post-surfactant chest radiographs on 94 preterm infants with RDS were analyzed and the pattern of chest radiographic response was classified as (a) clear, (b) recurrent opacities, and (c) no response. Their clinical characteristics were also recorded. Results. In 34 infants the RDS changes cleared within 3 days. 31 infants developed lung opacities within 10 days after an initial period of improvement. Twenty-nine infants failed to respond to the surfactant. The corresponding mean birth weights for the three groups were 1.74, 1.19, and 0.76 kg and the mean gestation ages 32.6, 27.7, and 25.4 weeks. The incidence of bronchopulmonary dysplasia (BPD) was highest among the slumping infants (72. % vs 50 % in no responders, P < 0.001) Conclusions. The pattern of chest radiographic response is primarily affected by gestation age and birth weight. Recurrent lung opacity after an initial positive response to surfactant therapy may be caused by such factors as edema from barotrauma and patent ductus arteriosus. Infants with intraventricular hemorrhage may demonstrate neurogenic edema. Other contributory factors include pneumonia and abnormal consumption of surfactant. Recurrent lung opacities after surfactant may be a predictor of chronic lung disease in the preterm infant. (orig.)

  14. Micellization of alkyl-propoxy-ethoxylate surfactants in water-polar organic solvent mixtures.

    Science.gov (United States)

    Sarkar, Biswajit; Lam, Stephanie; Alexandridis, Paschalis

    2010-07-06

    The effects of cosolvents (glycerol, ethanol, and isopropanol) on the self-assembly of novel alkyl-propoxy-ethoxylate surfactants in aqueous solutions have been investigated with a focus on the (i) quantification of solvent effects on the critical micelle concentration (cmc), (ii) free-energy contributions to micellization, (iii) local environment in the micellar solution, and (iv) structure of the micelles. The introduction of the polar organic solvents considered in this work into water decreases cohesive forces in the solvent mixture, resulting in an increase in the solubility of the surfactant molecules. As a result, micelle formation becomes less favorable and the cmc increases. The contribution of the cosolvent to the free energy of micellization is positive, and the data for different mixed solvents collapse onto a single straight line when plotted versus a function of the solubility parameters of the surfactant alkyl chains and the mixed solvents. The behavior of the poly(propylene oxide) part of the alkyl-propoxy-ethoxylate surfactants is hydrophilic, albeit less so in the ethanol-water mixed solvent than in plain water. Pyrene fluorescence emission I(1)/I(3) data suggest that the microenvironment in micellar solutions is affected mainly by the cosolvent concentration, not the surfactant degree of ethoxylation. Small-angle X-ray scattering data for both water and ethanol-water surfactant solutions are consistent with oblate ellipsoid micelles and reveal that the introduction of 20% ethanol decreases the micelle long axis by 10-15%.

  15. Influence of surfactant conditions on the structure of an upward bubbly channel flow

    Science.gov (United States)

    Ogasawara, Toshiyuki

    2005-11-01

    We investigated an upward bubbly channel flow and the effects of surfactant on its flow structure experimentally. 3-Pentanol and Triton X-100 are used as surfactants. By the addition of small amount of surfactant, bubble coalescences are prevented and mono-dispersed 1mm spherical bubbles are obtained. Under all of our experimental conditions, the added surfactants do not influence the single-phase turbulence. On the other hand, small amount of surfactant drastically changes the whole flow structure of bubbly flow. On the low concentration of 3-Pentanol (21-63ppm), bubbles strongly migrate towards the wall and these highly accumulated bubbles on the wall form crescent-like shaped horizontal bubble clusters of 10-40mm length. However, in 3-Pentanol solution of higher concentration (˜168ppm) or in the 2ppm Triton X-100 solution, the tendency of the lateral migration of bubbles is weaken and the bubbles are distributed uniformly in the channel. In the surfactant solution, the slip velocity on the bubble surface retards and the bubble rising velocity decreases (Marangoni effect). The change of boundary condition on the bubble surface affects not only drag force but shear-induced lift force. It is indicated that this change of shear-induced lift force greatly relates to the lateral migration of bubbles and the disaggregation of the bubble clusters. We also measured the turbulent properties using LDV and discuss the flow structure.

  16. Solubilization of octane in electrostatically-formed surfactant-polymer complexes.

    Science.gov (United States)

    Zhang, Hui; Zeeb, Benjamin; Salminen, Hanna; Feng, Fengqin; Weiss, Jochen

    2014-03-01

    Polymers can be used to modulate the stability and functionality of surfactant micelles. The purpose of this study was to investigate the solubilization of an octane oil-in-water emulsion in mixtures of an anionic polymer (carboxymethyl cellulose) and anionic sodium dodecylsulphate (SDS), nonionic polyoxyethylene sorbitan monooleate (Tween 80) and cationic cetyltrimethylammonium bromide (CTAB) surfactant micelles using dynamic light scattering, microelectrophoresis and turbidity measurements. The results showed that the addition of anionic carboxymethyl cellulose accelerated octane solubilization in cationic CTAB and CTAB-Tween 80 micelles, but did not affect the solubilization behaviors of micelles that were nonionic and anionic. The surfactant-polymer interactions were also studied using isothermal titration calorimetry (ITC) to characterize different physiochemical interaction regions depending on surfactant concentration in surfactant-polymer systems. Upon octane solubilization in CTAB-carboxymethyl cellulose mixtures, shape transitions of polymer-micelle complexes may have taken place that altered light scattering behavior. Based on these results, we suggest a mechanism for oil solubilization in electrostatically-formed surfactant-polymer complexes.

  17. Surfactant induced complex formation and their effects on the interfacial properties of seawater.

    Science.gov (United States)

    Guzmán, Eduardo; Santini, Eva; Benedetti, Alessandro; Ravera, Francesca; Ferrari, Michele; Liggieri, Libero

    2014-11-01

    The effect of a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), on the interfacial properties of seawater has been studied by dynamic and equilibrium surface tension and by dilational rheology essays. Important modifications of the surface tension and dilational rheology response have been observed already at the very low CTAB concentrations, where the effects due to the high ionic strength are negligible. The comparison with the effects of CTAB in different seawater models, or in natural seawater fractions, points out the establishment of strong interactions between the surfactant molecules and the lipophilic fraction of organic material dispersed/dissolved in seawater, affecting the interfacial activity of the molecules. Considering the biochemical richness of seawater, these results can be explained assuming interaction mechanisms and adsorption schemes similar to those speculated for protein and other macromolecules in the presence of surfactants, which in fact show similar features. Thus already at the low concentrations the surfactant molecules form highly surface-active complexes with part of the organic fraction of seawater. At the larger surfactant concentrations these complexes compete for adsorption with an excess of free CTAB molecules which, according to the thermodynamic conditions, are most favoured to occupy the liquid interface. The results of this study underline the important role of the sea organic content in enhancing the surface-activity of surfactants, which is relevant for a deeper understand of the direct and indirect effects of these types of pollutants on the physico-chemical environment in the sea coastal areas and develop mitigation strategies.

  18. Interactions of univalent counterions with headgroups of monomers and dimers of an anionic surfactant.

    Science.gov (United States)

    Jakubowska, Anna

    2015-03-24

    Specific ion effects in solution are related to the hydrated ion size and ion hydration, electrostatic interactions, dispersion forces, ion effects on water structure, and ion modification of surface tension. In this study, we tried to identify which factor determines the ion specificity observed. The preference and energy of metal cations binding with the headgroups of dodecylsulfate (DS) monomers and dimers were determined by mass spectrometry. In the gas phase, cation binding to DS dimer headgroups depends strongly on the cation radius. On the other hand, the interactions between DS monomer headgroups and chaotropic ions depend on the cation polarizability, and the binding of kosmotropic cations to DS monomer headgroups strongly depends on the Gibbs free energies of ion hydration. DS dimers are related to surfactants having doubly charged headgroups, and DS monomers are related to surfactants with singly charged headgroups. Our spectrometric study of the strength of counterion binding to free monomers of a surfactant provides insight into surfactant-counterion interactions at micellar interfaces in bulk solution.

  19. Rain Drop Charge Sensor

    Science.gov (United States)

    S, Sreekanth T.

    magnitude of initial drops from a precipitation event, gross cloud charge can be estimated and necessary precautions can be taken during convective cloud events. Being a site of high lightning incidence in tropics, Kerala state is affected in India and calls for much attention in lightning hazards mitigation. Installing this charge sensor and atmospheric electric field mill, an attempt to a better warning system can be attempted.

  20. Surfactant replacement therapy--economic impact.

    Science.gov (United States)

    Pejaver, R K; al Hifzi, I; Aldussari, S

    2001-06-01

    Surfactant replacement is an effective treatment for neonatal respiratory distress syndrome. (RDS). As widespread use of surfactant is becoming a reality, it is important to assess the economic implications of this new form of therapy. A comparison study was carried out at the Neonatal Intensive Care Unit (NICU) of Northwest Armed Forces Hospital, Saudi Arabia. Among 75 infants who received surfactant for RDS and similar number who were managed during time period just before the surfactant was available, but by set criteria would have made them eligible for surfactant. All other management modalities except surfactant were the same for all these babies. Based on the intensity of monitoring and nursing care required by the baby, the level of care was divided as: Level IIIA, IIIB, Level II, Level I. The cost per day per bed for each level was calculated, taking into account the use of hospital immovable equipment, personal salaries of nursing, medical, ancillary staff, overheads and maintenance, depreciation and replacement costs. Medications used, procedures done, TPN, oxygen, were all added to individual patient's total expenditure. 75 infants in the Surfactant group had 62 survivors. They spent a total of 4300 days in hospital. (av 69.35) Out of which 970 d (av 15.65 per patient) were ventilated days. There were 56 survivors in the non-surfactant group of 75. They had spent a total of 5023 days in the hospital (av 89.69/patient) out of which 1490 were ventilated days (av 26.60 d). Including the cost of surfactant (two doses), cost of hospital stay for each infant taking the average figures of stay would be SR 118, 009.75 per surfactant treated baby and SR 164, 070.70 per non-surfactant treated baby. The difference of 46,061 SR is 39.03% more in non-surfactant group. One Saudi rial = 8 Rs (approx at the time study was carried out.) Medical care cost varies from place to place. However, it is definitely cost-effective where surfactant is concerned. Quality adjusted

  1. 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.

  2. 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.

  3. Surfactant-Associated Bacteria in the Sea Surface Microlayer and their Effect on Remote Sensing Technology

    Science.gov (United States)

    Kurata, N.; Vella, K.; Tartar, A.; Matt, S.; Shivji, M.; Perrie, W. A.; Soloviev, A.

    2012-12-01

    Synthetic aperture radar remote sensing captures various fine-scale features on the ocean surface such as coastal discharges, oil pollution, vessel traffic, algal blooms and sea slicks. Although numerous factors potentially affect the synthetic aperture radar imaging process, the influence of biogenic and anthropogenic surfactants has been suggested as one of the primary parameters, especially under relatively low wind conditions. Surfactants have a tendency to dampen the short gravity-capillary ocean waves causing the sea surface to smoothen, thus allowing the radar to detect areas of surfactants. Surfactants are found in sea slicks, which are the accumulation of organic material shaped as elongated bands on the ocean's surface. Sea slicks are often observable with the naked eye due to their glassy appearance and can also be seen on synthetic aperture radar images as dark scars. While the sources of surfactants can vary, some are known to be of marine bacteria origin. Countless numbers of marine bacteria are present in the oceanic environment, and their biogeochemical contributions cannot be overlooked. Not only does marine-bacteria produce surfactants, but they also play an important role in the transformation of surfactants. In this study, we profiled the surfactant-associated bacteria composition within the biogenic thin layer of the ocean surface more commonly referred as the sea surface microlayer. Bacterial samples were collected from the sea surface microlayer for comparative analysis from both within and outside of sea slick areas as well as the underlying subsurface water. The bacterial microlayer sampling coincided with synthetic aperture radar satellite, RADARSAT-2, overpasses to demonstrate the simultaneous in-situ measurements during a satellite image capture. The sea surface microlayer sampling method was designed to enable aseptic bacterial sampling. A 47 mm polycarbonate membrane was utilized at each sampling site to obtain a snapshot of the

  4. Biobased surfactant-like molecules from organic wastes: the effect of waste composition and composting process on surfactant properties and on the ability to solubilize Tetrachloroethene (PCE).

    Science.gov (United States)

    Quadri, Giorgia; Chen, Xiaosong; Jawitz, James W; Tambone, Fulvia; Genevini, Pierluigi; Faoro, Franco; Adani, Fabrizio

    2008-04-01

    In this work, four surfactant-like humic acids (HAs) obtained from garden lignocellulose wastes and kitchen food wastes mixed with garden-lignocellulose wastes, both before and after composting, were tested for surfactant properties and the ability to solubilize tetrachloroethene (PCE). The waste-derived HAs showed good surfactant properties, lowering the water surface tension from 74 mN m(-1) to 45.4 +/- 4.4 mN m(-1), with a critical micelle concentration (CMC) of 1.54 +/- 1.68 g L(-1), which is lower than many synthetic ionic surfactants. CMC was affected by both waste origin and composting processes. The addition of food waste and composting reduced CMC by adding alkyl-C (measured by CP MAS 13C NMR) and N- and S-HA contents (amide molecules), so that a multistep regression was found [CMC = 24.6 - 0.189 alkyl C - 2.64 (N + S); R2 = 0.77, P < 0.10, n = 6]. The four HAs solubilized PCE at the rate of 0.18-0.47 g PCE/g aqueous biosurfactant. These results were much higher than those reported in the literature for a commercial HA (0.026 g/g), but they were in line with those measured in this work for nonionic surfactants such as Tween-80 (0.69 g/g) and Triton X-100 (1.08 g/g).

  5. 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.

  6. Fluorescence emission of pyrene in surfactant solutions.

    Science.gov (United States)

    Piñeiro, Lucas; Novo, Mercedes; Al-Soufi, Wajih

    2015-01-01

    The systematic description of the complex photophysical behaviour of pyrene in surfactant solutions in combination with a quantitative model for the surfactant concentrations reproduces with high accuracy the steady-state and the time resolved fluorescence intensity of pyrene in surfactant solutions near the cmc, both in the monomer and in the excimer emission bands. We present concise model equations that can be used for the analysis of the pyrene fluorescence intensity in order to estimate fundamental parameters of the pyrene-surfactant system, such as the binding equilibrium constant K of pyrene to a given surfactant micelle, the rate constant of excimer formation in micelles, and the equilibrium constant of pyrene-surfactant quenching. The values of the binding equilibrium constant K(TX100)=3300·10³ M⁻¹ and K(SDS)=190·10³ M⁻¹ for Triton X-100 (TX100) and SDS micelles, respectively, show that the partition of pyrene between bulk water and micelles cannot be ignored, even at relatively high surfactant concentrations above the cmc. We apply the model to the determination of the cmc from the pyrene fluorescence intensity, especially from the intensity ratio at two vibronic bands in the monomer emission or from the ratio of excimer to monomer emission intensity. We relate the finite width of the transition region below and above the cmc with the observed changes in the pyrene fluorescence in this region.

  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. Fluorescent Ensemble Based on Bispyrene Fluorophore and Surfactant Assemblies: Sensing and Discriminating Proteins in Aqueous Solution.

    Science.gov (United States)

    Fan, Junmei; Ding, Liping; Bo, Yu; Fang, Yu

    2015-10-14

    A particular bispyrene fluorophore (1) with two pyrene moieties covalently linked via a hydrophilic spacer was synthesized. Fluorescence measurements reveal that the fluorescence emission of 1 could be well modulated by a cationic surfactant, dodecyltrimethylammonium bromide (DTAB). Protein sensing studies illustrate that the selected ensemble based on 1/DTAB assemblies exhibits ratiometric responses to nonmetalloproteins and turn-off responses to metalloproteins, which can be used to differentiate the two types of proteins. Moreover, negatively charged nonmetalloproteins can be discriminated from the positively charged ones according to the difference in ratiometric responses. Fluorescence sensing studies with control bispyrenes indicate that the polarity of the spacer connecting two pyrene moieties plays an important role in locating bispyrene fluorophore in DTAB assemblies, which further influences its sensing behaviors to noncovalent interacting proteins. This study sheds light on the influence of the probe structure on the sensing performance of a fluorescent ensemble based on probe and surfactant assemblies.

  9. 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...

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

    Science.gov (United States)

    Pietralik, Zuzanna; Kołodziejska, Żaneta; Weiss, Marek; Kozak, Maciej

    2015-01-01

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

  11. 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.

  12. Synthesis and Characterization of Zirconia Nanocrystallites by Cationic Surfactant and Anionic Surfactant

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Study on nanomaterials has attracted great interests in recent years. In this article,zirconia nanocrystallites of different structures have been successfully synthesized via hydrothermal methods with cationic surfactant (CTAB) and anionic surfactant (SDS), respectively. Differential Scanning Calorimeter (DSC-TG), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM), Ultraviolet-Visible (UV-vis) and N2 adsorption-desorption analyses are used for their structure characteristics. The results show that the cationic surfactant has a distinctive direction effect on the formation of zirconia nanocrystallites, while the anionic surfactant has a self-assembly synergistic effect on them. The sample synthesized with the cationic surfactant presents good dispersion with the main phase of tetragonal zirconia, and the average nanocryst al size is around 15nm after calcination at 500 ℃. While the sample synthesized with the anionic surfactant exhibits a worm-like mesoporous structure with pure tetragonal phase after calcination at 500 ℃ and with good thermal stability.

  13. Liquid-liquid extraction for surfactant-contaminant separation and surfactant reuse

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, M.A. [Surbec Environmental, Norman, OK (United States); Sabatini, D.A.; Harwell, J.H. [Univ. of Oklahoma, Norman, OK (United States)

    1997-07-01

    Liquid-liquid extraction was investigated for use with surfactant enhanced subsurface remediation. A surfactant liquid-liquid extraction model (SLLEM) was developed for batch equilibrium conditions based on contaminant partitioning between micellar, water, and solvent phases. The accuracy of this fundamental model was corroborated with experimental results (using naphthalene and phenanthrene as contaminants and squalane as the extracting solvent). The SLLEM model was then expanded to nonequilibrium conditions. The effectiveness of this nonequilibrium model was corroborated with experimental results from continuous flow hollow fiber membrane systems. The validated models were used to conduct a sensitivity analysis evaluating the effects of surfactants on the removal of the contaminants in liquid-liquid extraction systems. In addition, liquid-liquid extraction is compared to air stripping for surfactant-contaminant separation. Finally, conclusions are drawn as to the impact of surfactants on liquid-liquid extraction processes, and the significance of these impacts on the optimization of surfactant-enhanced subsurface remediation.

  14. Fine tuning of magnetite nanoparticle size distribution using dissymmetric potential pulses in the presence of biocompatible surfactants and the electrochemical characterization of the nanoparticles.

    Science.gov (United States)

    Rodríguez-López, A; Cruz-Rivera, J J; Elías-Alfaro, C G; Betancourt, I; Ruiz-Silva, H; Antaño-López, R

    2015-01-01

    The effects of varying the surfactant concentration and the anodic pulse potential on the properties and electrochemical behaviors of magnetite nanoparticles were investigated. The nanoparticles were synthesized with an electrochemical method based on applying dissymmetric potential pulses, which offers the advantage that can be used to tune the particle size distribution very precisely in the range of 10 to 50 nm. Under the conditions studied, the surfactant concentration directly affects the size distribution, with higher concentrations producing narrower distributions. Linear voltammetry was used to characterize the electrochemical behavior of the synthesized nanoparticles in both the anodic and cathodic regions, which are attributed to the oxidation of Fe(2+) and the reduction of Fe(3+); these species are part of the spinel structure of magnetite. Electrochemical impedance spectroscopy data indicated that the reduction and oxidation reactions of the nanoparticles are not controlled by the mass transport step, but by the charge transfer step. The sample with the highest saturation magnetization was that synthesized in the presence of polyethylene glycol.

  15. 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 C12TAB (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.

  16. Charged Leptons

    CERN Document Server

    Albrecht, J; Babu, K; Bernstein, R H; Blum, T; Brown, D N; Casey, B C K; Cheng, C -h; Cirigliano, V; Cohen, A; Deshpande, A; Dukes, E C; Echenard, B; Gaponenko, A; Glenzinski, D; Gonzalez-Alonso, M; Grancagnolo, F; Grossman, Y; Harnik, R; Hitlin, D G; Kiburg, B; Knoepfe, K; Kumar, K; Lim, G; Lu, Z -T; McKeen, D; Miller, J P; Ramsey-Musolf, M; Ray, R; Roberts, B L; Rominsky, M; Semertzidis, Y; Stoeckinger, D; Talman, R; Van De Water, R; Winter, P

    2013-01-01

    This is the report of the Intensity Frontier Charged Lepton Working Group of the 2013 Community Summer Study "Snowmass on the Mississippi", summarizing the current status and future experimental opportunities in muon and tau lepton studies and their sensitivity to new physics. These include searches for charged lepton flavor violation, measurements of magnetic and electric dipole moments, and precision measurements of the decay spectrum and parity-violating asymmetries.

  17. Synthesis of novel quaternary ammonium surfactants containing adamantane

    Institute of Scientific and Technical Information of China (English)

    Jian Wei Guo; Xing Zhong; Hua Zhu; Li Juan Feng; Ying De Cui

    2012-01-01

    A series of novel quaternary ammonium surfactants containing adamantane were designed and synthesized from 1-adamantanecarboxylic acid.The structures of target surfactants were confirmed by 1H NMR,elements analysis and FTIR.Surface properties of these surfactants were investigated.Due to the lipophilicity of adamantane,the critical micelle concentration (CMC) and C20 values of the synthesized quaternary ammonium surfactants are lower than that of conventional quaternary ammonium surfactants.

  18. Preparation of nanocrystalline MgO by surfactant assisted precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, Mehran, E-mail: rezaei@kashanu.ac.ir [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Khajenoori, Majid; Nematollahi, Behzad [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

    2011-10-15

    Highlights: {yields} Nanocrystalline magnesium oxide with high surface area. {yields} MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. {yields} MgO prepared with surfactant showed a plate-like shape. {yields} Refluxing temperature and time and the surfactant to metal molar ratio affect the textural properties of MgO. -- Abstract: Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly (ethylene glycol)-block, Poly (propylene glycol)-block, Poly (ethylene glycol)) as surfactant and under refluxing conditions. The prepared samples were characterized by X-ray diffraction (XRD), N{sub 2} adsorption (BET) and scanning and transmission electron microscopies (SEM and TEM). The obtained results revealed that the refluxing time and temperature and the molar ratio of surfactant to metal affect the structural properties of MgO, because of the changes in the rate and extent of P123 adsorption on the prepared samples. The results showed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. With increasing the P123/MgO molar ratio to 0.05 the pore size distribution was shifted to larger size. The sample prepared with addition of surfactant showed a plate-like shape which was completely different with the morphology of the sample prepared without surfactant. The formation of nanoplate-like MgO was related to higher surface density of Mg ions on the (0 0 1) plane than that on the other planes of the Mg(OH){sub 2} crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH){sub 2} nanoentities and the growth on the (0 0 1) plane would be markedly restricted, and the consequence is the generation of nanoplate-like MgO. In addition, increase in refluxing temperature and time

  19. Molecular-thermodynamic theory of micellization of multicomponent surfactant mixtures: 2. pH-sensitive surfactants.

    Science.gov (United States)

    Goldsipe, Arthur; Blankschtein, Daniel

    2007-05-22

    In article 1 of this series, we developed a molecular-thermodynamic (MT) theory to model the micellization of mixtures containing an arbitrary number of conventional (pH-insensitive) surfactants. In this article, we extend the MT theory to model mixtures containing a pH-sensitive surfactant. The MT theory was validated by examining mixtures containing both a pH-sensitive surfactant and a conventional surfactant, which effectively behave like ternary surfactant mixtures. We first compared the predicted micellar titration data to experimental micellar titration data that we obtained for varying compositions of mixed micelles containing the pH-sensitive surfactant dodecyldimethylamine oxide (C12DAO) mixed with either a cationic surfactant (dodecyltrimethylammonium bromide, C12TAB), a nonionic surfactant (dodecyl octa(ethylene oxide), C12E8), or an anionic surfactant (sodium dodecyl sulfate, SDS) surfactant. The MT theory accurately modeled the titration behavior of C12DAO mixed with C12E8. However, C12DAO was observed to interact more favorably with SDS and with C12TAB than was predicted by the MT theory. We also compared predictions to data from the literature for mixtures of C12DAO and SDS. Although the pH values of solutions with no added acid were modeled with only qualitative accuracy, the MT theory resulted in quantitatively accurate predictions of solution pH for mixtures containing added acid. In addition, the predicted degree of counterion binding yielded a lower bound to the experimentally measured value. Finally, we predicted the critical micelle concentration (cmc) of solutions of two pH-sensitive surfactants, tetradecyldimethylamine oxide (C14DAO) and hexadecyldimethyl betaine (C16Bet), at varying solution pH and surfactant composition. However, at the pH values considered, the pH sensitivity of C16Bet could be neglected, and it was equivalently modeled as a zwitterionic surfactant. The cmc's predicted using the MT theory agreed well with the experimental

  20. 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.

  1. Effects of Interactions Among Surfactants,Water and Oil on Equilibrium Configuration of Surfactant-Water-Oil Systems

    Institute of Scientific and Technical Information of China (English)

    YUAN Yin-quan; SUN Zhi-bo; XIE Yun; ZOU Xian-wu

    2004-01-01

    The distribution and configuration of surfactants at interface in surfactant-water-oil systems have been investigated using discontinuous molecular dynamic simulations. There exists a certain equilibrium concentration of surfactants at interface for the systems with certain interactions among surfactant, water and oil. The interface length and equilibrium morphology of the systems are dependent on the equilibrium concentration of surfactants at interface and the total amount of surfactants. The interaction strengths among surfactant, water and oil determine the equilibrium concentration of surfactants at interface. Three typical configurations of surfactants at interface have been observed: ① surfactant molecules are perpendicular to the interface and arranged closely; ② perpendicular to the interface and arranged at interval of two particles; ③ lie down in the interface partly.

  2. Structure and dynamics of a protein-surfactant assembly studied by ion-mobility mass spectrometry and molecular dynamics simulations.

    Science.gov (United States)

    Borysik, Antoni J

    2015-09-01

    The structure and dynamics of a protein-surfactant assembly studied by ion-mobility mass spectrometry (IMS) and vacuum molecular dynamics (MD) simulations is reported. Direct evidence is provided for the ability of the surfactant dodecyl-β-D-maltoside (DDM) to prevent charge-induced unfolding of the membrane protein (PagP) in the gas-phase. Restraints obtained by IMS are used to map the surfactant positions onto the protein surface. Surfactants occupying more exposed positions at the apexes of the β-barrel structure are most in-line with the experimental observations. MD simulations provide additional evidence for this assembly organization through surfactant inversion and migration on the protein structure in the absence of solvent. Surfactant migration entails a net shift from apolar membrane spanning regions to more polar regions of the protein structure with the DDM molecule remaining attached to the protein via headgroup interactions. These data provide evidence for the role of protein-DDM headgroup interactions in stabilizing membrane protein structure from gas-phase unfolding.

  3. Aggregation of sulfosuccinate surfactants in water

    Energy Technology Data Exchange (ETDEWEB)

    Magid, L.J.; Daus, K.A.; Butler, P.D.; Quincy, R.B.

    1983-12-22

    The aggregation of sodium di-n-alkyl sulfosuccinates in water (H/sub 2/O and D/sub 2/O at 45/sup 0/C) has been investigated. A self-consistent picture of the dependence of sodium ion binding on surfactant concentration is obtained from emf measurements, conductimetry, and small-angle neutron scattering (SANS) measurements. The concentration dependence of the micellar agregation number for the sulfosuccinates and related double-tailed surfactants depends markedly on surfactant solubility. A sphere-to-disk transition in micellar shape, which might have been expected as a precursor to formation of a lamellar mesophase, was not observed as the surfactant concentration was increased. 8 figures, 2 tables.

  4. Amphiphilic biopolymers (amphibiopols) as new surfactants for membrane protein solubilization

    Science.gov (United States)

    Duval-Terrié, Caroline; Cosette, Pascal; Molle, Gérard; Muller, Guy; Dé, Emmanuelle

    2003-01-01

    The aim of this study was to develop new surfactants for membrane protein solubilization, from a natural, biodegradable polymer: the polysaccharide pullulan. A set of amphiphilic pullulans (HMCMPs), differing in hydrophobic modification ratio, charge ratio, and the nature of the hydrophobic chains introduced, were synthesized and tested in solubilization experiments with outer membranes of Pseudomonas fluorescens. The membrane proteins were precipitated, and then resolubilized with various HMCMPs. The decyl alkyl chain (C10) was the hydrophobic graft that gave the highest level of solubilization. Decyl alkyl chain-bearing HMCMPs were also able to extract integral membrane proteins from their lipid environment. The best results were obtained with an amphiphilic pullulan bearing 18% decyl groups (18C10). Circular dichroism spectroscopy and membrane reconstitution experiments were used to test the structural and functional integrity of 18C10-solubilized proteins (OmpF from Escherichia coli and bacteriorhodopsin from Halobacterium halobium). Whatever their structure type (α or β), 18C10 did not alter either the structure or the function of the proteins analyzed. Thus, HMCMPs appear to constitute a promising new class of polymeric surfactants for membrane protein studies. PMID:12649425

  5. Analysis of pulmonary surfactant in rat lungs after inhalation of nanomaterials: Fullerenes, nickel oxide and multi-walled carbon nanotubes.

    Science.gov (United States)

    Kadoya, Chikara; Lee, Byeong-Woo; Ogami, Akira; Oyabu, Takako; Nishi, Ken-ichiro; Yamamoto, Makoto; Todoroki, Motoi; Morimoto, Yasuo; Tanaka, Isamu; Myojo, Toshihiko

    2016-01-01

    The health risks of inhalation exposure to engineered nanomaterials in the workplace are a major concern in recent years, and hazard assessments of these materials are being conducted. The pulmonary surfactant of lung alveoli is the first biological entity to have contact with airborne nanomaterials in inhaled air. In this study, we retrospectively evaluated the pulmonary surfactant components of rat lungs after a 4-week inhalation exposure to three different nanomaterials: fullerenes, nickel oxide (NiO) nanoparticles and multi-walled carbon nanotubes (MWCNT), with similar levels of average aerosol concentration (0.13-0.37 mg/m(3)). Bronchoalveolar lavage fluid (BALF) of the rat lungs stored after previous inhalation studies was analyzed, focusing on total protein and the surfactant components, such as phospholipids and surfactant-specific SP-D (surfactant protein D) and the BALF surface tension, which is affected by SP-B and SP-C. Compared with a control group, significant changes in the BALF surface tension and the concentrations of phospholipids, total protein and SP-D were observed in rats exposed to NiO nanoparticles, but not in those exposed to fullerenes. Surface tension and the levels of surfactant phospholipids and proteins were also significantly different in rats exposed to MWCNTs. The concentrations of phospholipids, total protein and SP-D and BALF surface tension were correlated significantly with the polymorphonuclear neutrophil counts in the BALF. These results suggest that pulmonary surfactant components can be used as measures of lung inflammation.

  6. Surfactant apoprotein in nonmalignant pulmonary disorders.

    OpenAIRE

    Singh, G.; Katyal, S. L.

    1980-01-01

    Formalin-fixed, paraffin-embedded lungs exhibiting a variety of nonmalignant disorders were studied by immunoperoxidase staining using antibodies specific for surfactant apoprotein, IgG, IgM, IgA, albumin, fibrinogen, and lysozyme. Normal Type II pneumocytes showed staining for surfactant apoprotein in the perinuclear region only. The extent and intensity of staining for apoprotein was markedly increased in reactive Type II pneumocytes. This increase appeared to be a nonspecific reaction to l...

  7. Investigation of a polyether trisiloxane surfactant

    OpenAIRE

    Michel, Amandine

    2016-01-01

    Thanks to their adaptability and high efficiency compared to traditional carbon based surfactants, silicone surfactants are a success in many different applications, from pesticides to cosmetics, polyurethane foam, textile and car care products. In spite of those numerous applications, no analytical method existed for their trace determination in environmental samples and no data have been available regarding their environmental occurrence and fate. An analytical method for the trace ana...

  8. Serum-surfactant SP-D correlates inversely to lung function in cystic fibrosis

    DEFF Research Database (Denmark)

    Olesen, Hanne Vebert; Holmskov, Uffe; Schiøtz, Peter Oluf;

    2010-01-01

    BACKGROUND: Cystic fibrosis (CF) affects the lungs causing infections and inflammation. Surfactant protein D (SP-D) is an innate defense lectin primarily secreted in the lungs. We investigated the influence of the SP-D Met11Thr polymorphism on CF lung function; and serum SP-D as a marker for CF...

  9. Severe adverse effects related to dermal exposure to a glyphosate-surfactant herbicide

    DEFF Research Database (Denmark)

    Mariager, T P; Madsen, P V; Ebbehøj, N E

    2013-01-01

    This is a case of severe chemical burns following prolonged accidental exposure to a glyphosate-surfactant herbicide. The patient developed local swelling, bullae and exuding wounds. Neurological impairment followed affecting finger flexion and sensation with reduced nerve conduction. Imaging...... revealed oedema of the soft tissue and juxta-articular osteopenia, and a causal relationship to exposure is suggested....

  10. Spinodal Decomposition in Mixtures Containing Surfactants

    Science.gov (United States)

    Melenekvitz, J.

    1998-03-01

    Spinodal decomposition in mixtures containing two immiscible liquids (A and B) plus surfactant was investigated using a recently developed (J. Melenkevitz and S. H. Javadpour, J. Chem. Phys., 107, 623 (1997).) 3-component Ginzburg-Landau model. The time dependent Ginzburg-Landau (TDGL) equations governing the evolution of structure were numerically integrated in 2-dimensions. We found the growth rate of the average domain size, R(t), decreased with increasing surfactant concentration over a wide range of relative amounts of A and B. This can be attributed to the surfactant accumulating at the growing interface between the immiscible liquids, which leads to a reduction in the surface tension. At late times, the growth rate was noticeably altered when thermal fluctuations were added to the numerical simulations. In this case, power law behavior was observed for R(t) at late times, R(t) ~ t^α, with the exponent α decreasing as the amount of surfactant increased. The dynamics at early times were determined by linearizing the TDGL equations about a uniformly mixed state. The growth rate at ealry times was found to be strongly dependent on the model parameters describing the surfactant miscibility in A and B and the surfactant strength. Comparison with recent measurements on SBR / PB mixtures with added PB-SBR diblock copolymer will also be presented.

  11. Performance of some surfactants as wetting agents

    Energy Technology Data Exchange (ETDEWEB)

    Shalaby, M.N.; El-Shanny, O.A.A. [Egyptian Petroleum Research Institute (EPRI), Cairo (Egypt). Evaluation and Analysis Dept.

    2005-12-01

    The wetting power of anionic surfactant: sodium dodecyl sulfate (SDS), and nonionic surfactants: polyoxyethelene(14)monolaurate [La(EO){sub 14}] and polyoxyethelene(14)monoeleate [OI(EO){sub 14}] has been studied to determine their performance as wetting agents. The study reveals that the nonionic compound with a long hydrophobic chain exhibits higher wettability than the shorter one when used at very low cocentrations (below CMC) and the reverse is shown with high concentrations (above CMC). the wetting power of the investigated surfactants increases as the CMC values increases. In case of the nonionic compounds and at surfactant concentrations equal their CMC values, OI(EO){sub 14} shows a higher wetting power than La(EO){sub 14} while is possesses a lower HLB value. The anionic surfactant shows an optimum wetting in comparison with the tested nonionic one. The wettability of all the investigated samples increases as the surface tension of their solutions increases to the allowed limit that can be reached in the presence of surfactant. (orig.)

  12. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2005-01-01

    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. Imbibition in an originally oil-wet 2D capillary is the fastest in the case of Alf-38 and slowest in the case of DTAB (among the surfactants studied). Force of adhesion studies and contact angle measurements show that greater wettability alteration is possible with these anionic surfactants than the cationic surfactant studied. The water imbibition rate does not increase monotonically with an increase in the surfactant concentration. A numerical model has been developed that fits the rate of imbibition. Plans for the next quarter include conducting simulation and imbibition studies.

  13. Evaluation of Surfactant Effects on Newborns

    Directory of Open Access Journals (Sweden)

    N. Khalessi

    2006-10-01

    Full Text Available Introduction & Objective: One of the standard therapies in neonates with severe respiratory distress syndrome (RDS is surfactant administration in early course of therapy that cause reduction in mortality, pneumothorax and need to mechanical ventilation. In this study that was carried out in Aliasghar Hospital NICU in 1994-1995 & 2001-2002, the goal was to compare two groups of neonates with severe RDS that had been ventilated in the first 24 hours but one group had received surfactant and the other group (7 years ago was deprived of this substance. Materials & Methods: In our study, 36 neonates that received surfactant and 52 neonates with only mechanical ventilation therapy were compared. Data collected and analyzed using SPSS.Results: We found that mortality in patients with surfactant administration was significantly lower compared to the second group who did not receive surfactant. There were not any significant differences in incidences of HIV, pneumothorax, sepsis, and PDA and also course of hospitalization and need to ventilation between two groups. Conclusion: As a result, all of these findings reflect obligatory surfactant administration in sever RDS in NICU under observation of an educated expert.

  14. Nonlinear water waves with soluble surfactant

    Science.gov (United States)

    Lapham, Gary; Dowling, David; Schultz, William

    1998-11-01

    The hydrodynamic effects of surfactants have fascinated scientists for generations. This presentation describes an experimental investigation into the influence of a soluble surfactant on nonlinear capillary-gravity waves in the frequency range from 12 to 20 Hz. Waves were generated in a plexiglass wave tank (254 cm long, 30.5 cm wide, and 18 cm deep) with a triangular plunger wave maker. The tank was filled with carbon- and particulate-filtered water into which the soluble surfactant Triton-X-100® was added in known amounts. Wave slope was measured nonintrusively with a digital camera running at 225 fps by monitoring the position of light beams which passed up through the bottom of the tank, out through the wavy surface, and onto a white screen. Wave slope data were reduced to determine wave damping and the frequency content of the wave train. Both were influenced by the presence of the surfactant. Interestingly, a subharmonic wave occurring at one-sixth the paddle-driving frequency was found only when surfactant was present and the paddle was driven at amplitudes high enough to produce nonlinear waves in clean water. Although the origins of this subharmonic wave remain unclear, it appears to be a genuine manifestation of the combined effects of the surfactant and nonlinearity.

  15. Lung remodeling in aging surfactant protein D deficient mice.

    Science.gov (United States)

    Schneider, Jan Philipp; Arkenau, Martina; Knudsen, Lars; Wedekind, Dirk; Ochs, Matthias

    2017-02-07

    Pulmonary surfactant, a mixture of lipids and proteins at the air-liquid interface of alveoli, prevents the lungs from collapsing due to surface tension. One constituent is surfactant-associated protein-D (SP-D), a protein involved in surfactant homeostasis and innate immunity. Mice deficient in SP-D (SP-D (-/-)) has been described as developing a characteristic phenotype which affects the surfactant system (including changes in the intra-cellular and intra-alveolar surfactant pool, alveolar epithelial type II cells and alveolar macrophages), lung architecture and its inflammatory state (development of an emphysema-like pathology, inflammatory cell infiltration). Furthermore, it has been described that these mice develop sub-pleural fibrosis and a thickening of alveolar septal walls. The aim of the present study was to systematically investigate the long term progression of this phenotype with special focus on parenchymal remodeling, whether there are progressive emphysematous changes and whether there is progressive septal wall thickening which might indicate the development of pulmonary fibrosis. By means of design-based stereology and light microscopy, lungs of wild type (wt) and SP-D (-/-) mice of four age groups (3, 6, 12 and ∼18 months) were investigated. The data do not suggest a relevant spontaneous pro-fibrotic remodeling or a destructive process in the aging SP-D (-/-) mice. We demonstrated neither a significant destructive emphysema nor significant thickening of alveolar septal walls, but the data suggest an increase in the number weighted mean alveolar volume in aging SP-D (-/-) mice without loss of alveoli or alveolar epithelial surface area per lung. This increase may reflect over-distension due to altered mechanical properties of alveoli. In the light of our findings and data from the literature, the question arises as to whether a lack of SP-D promotes structural changes in the lung which have been described as being associated with aging lungs

  16. Imidazolium-based ionic liquid-type surfactant as pseudostationary phase in micellar electrokinetic chromatography of highly hydrophilic urinary nucleosides.

    Science.gov (United States)

    Rageh, Azza H; Pyell, Ute

    2013-11-05

    Ionic liquid (IL)-type surfactants have been shown to interact more strongly with polar compounds than traditionally used quaternary ammonium cationic surfactants. The aim of this study is to provide an alternative micellar electrokinetic chromatographic method (MEKC) for the analysis of urinary nucleosides in their ionic form at low surfactant concentration. This approach could overcome the use of high surfactant concentrations typically associated with the analysis of these highly hydrophilic metabolites as neutral species, which is frequently accompanied by high electric current, Joule heating and long analysis time. The investigated IL-type surfactant; 1-tetradecyl-3-methylimidazolium bromide (C14MImBr) is similar to the commonly employed cationic surfactant; tetradecyltrimethylammonium bromide (TTAB) but it provides a different separation selectivity. We employed C14MImBr micelles for the MEKC analysis of seven urinary nucleosides. The studied analytes possess a negative charge at pH 9.38 (exceptions are adenosine and cytidine which are neutral at this pH value). Borate imparts an additional negative charge to these compounds after complexation with the cis-diol functionality of the ribose unit, which in turn enables them to interact with the oppositely charged C14MImBr micelles via electrostatic (Coulomb) forces. The effect of the concentration of borate (the complexing, competing and buffering ion) on the effective electrophoretic mobilities and on the retention factors was investigated. The effective electrophoretic mobility data show that complexation between these nucleosides and borate occurs with high degree of complexation even at very low borate concentration (2.5 mmol L(-1) disodium tetraborate). In addition, we found that the retention factors are strongly dependent on the borate concentration being the highest when using the lowest borate concentration and they can be regulated by variation of either tetraborate concentration or the pH of the

  17. Interaction Study and Reactivity of Zr(IV) -Substituted Wells-Dawson Polyoxometalate towards Hydrolysis of Peptide Bonds in Surfactant Solutions.

    Science.gov (United States)

    Quanten, Thomas; Shestakova, Pavletta; Van Den Bulck, Dries; Kirschhock, Christine; Parac-Vogt, Tatjana N

    2016-03-01

    The interaction between the 1:2 Zr(IV) :Wells-Dawson complex, K15 H[Zr(α2 -P2 W17 O61 )2] (1), and a range of surfactants was studied in detail with the aim of developing metal-substituted POMs as potential artificial proteases for membrane proteins. The surfactants include the positively charged cetyl(trimethyl)ammonium bromide (CTAB), the negatively charged sodium dodecyl sulfate (SDS), the neutral Triton X-100 (TX-100), and zwitterionic 3-[dodecyl(dimethyl)ammonio]-1-propanesulfonate (Zw3-13) and 3-[dimethyl(3-{[(3α,5β,7α,12α)-3,7,12-trihydroxy-24-oxocholan-24-yl]amino}propyl)ammonio]-1-propanesulfonate (CHAPS). A combination of multinuclear (1)H, (13)C, and (31) P NMR spectroscopy, (1)H diffusion-ordered NMR spectroscopy ((1)H DOSY), and nuclear Overhauser effect spectroscopy (NOESY) was used to examine the interaction between 1 and each surfactant on the molecular level. Cationic surfactant CTAB caused precipitation of 1 due to strong electrostatic interactions, while the anionic SDS and neutral TX-100 surfactants did not exhibit any interaction at neutral pD. (1)H DOSY NMR spectroscopy indicated an interaction between 1 and zwitterionic surfactants Zw3-12 and CHAPS, which occurs via the positively charged ammonium group in the surfactant molecule. In the presence of anionic, neutral, and zwitterionic surfactants, 1 preserves its catalytic activity towards the hydrolysis of the peptide bond in the dipeptide glycyl-l-histidine (GH). The fastest hydrolysis was observed at pD 7.0 and could be rationalized by taking into account pD-dependent speciation of 1 and coordination properties of GH.

  18. Butterflies with rotation and charge

    Science.gov (United States)

    Reynolds, Alan P.; Ross, Simon F.

    2016-11-01

    We explore the butterfly effect for black holes with rotation or charge. We perturb rotating BTZ and charged black holes in 2 + 1 dimensions by adding a small perturbation on one asymptotic region, described by a shock wave in the spacetime, and explore the effect of this shock wave on the length of geodesics through the wormhole and hence on correlation functions. We find the effect of the perturbation grows exponentially at a rate controlled by the temperature; dependence on the angular momentum or charge does not appear explicitly. We comment on issues affecting the extension to higher-dimensional charged black holes.

  19. Butterflies with rotation and charge

    CERN Document Server

    Reynolds, Alan P

    2016-01-01

    We explore the butterfly effect for black holes with rotation or charge. We perturb rotating BTZ and charged black holes in 2+1 dimensions by adding a small perturbation on one asymptotic region, described by a shock wave in the spacetime, and explore the effect of this shock wave on the length of geodesics through the wormhole and hence on correlation functions. We find the effect of the perturbation grows exponentially at a rate controlled by the temperature; dependence on the angular momentum or charge does not appear explicitly. We comment on issues affecting the extension to higher-dimensional charged black holes.

  20. Charge transport in polymeric transistors

    Directory of Open Access Journals (Sweden)

    Alberto Salleo

    2007-03-01

    Full Text Available Polymeric semiconductors have attracted much attention because of their possible use as active materials in printed electronics. Thin-film transistors (TFTs are a convenient tool for studying charge-transport physics in conjugated polymers. Two families of materials are reviewed here: fluorene copolymers and polythiophenes. Because charge transport is highly anisotropic in molecular conductors, the electrical properties of conjugated polymers are strongly dependent on microstructure. Molecular weight, polydispersity, and regioregularity all affect morphology and charge-transport in these materials. Charge transport models based on microstructure are instrumental in identifying the electrical bottlenecks in these materials.

  1. Silicone antifoam performance enhancement by nonionic surfactants in potato medium.

    Science.gov (United States)

    Christiano, Steven P; Fey, Kenneth C

    2003-01-01

    The ability of a silicone antifoam to retard foaming in a liquor prepared from potatoes is enhanced by the addition of ethoxylated nonionic surfactants. The enhancement is non-linear for surfactant concentration, with all 12 surfactants tested possessing a concentration at which foam heights strongly diminish, referred to as the surfactant critical antifoaming concentration (SCAFC). SCAFCs vary between surfactants, with lower values indicating better mass efficiency of antifoaming enhancement. SCAFCs decrease with degree of ethoxylation and decrease with the hydrophilic-lipophilic balance for ethoxylated nonionic surfactants. Surfactant addition produces a mixed water-surface layer containing surfactant and surface-active components in the potato medium. Surface tension reduction does not correlate well with antifoam performance enhancement. A model is proposed where surfactant adsorption promotes desorption of surface-active potato medium components from the water surface. At the SCAFC, desorption is not complete, yet the rate of bubble rupture is sufficiently enhanced to provide excellent foam control.

  2. 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.

  3. Adsorptive Removal of Copper by Using Surfactant Modified Laterite Soil

    Directory of Open Access Journals (Sweden)

    Tien Duc Pham

    2017-01-01

    Full Text Available Removal of copper ion (Cu2+ by using surfactant modified laterite (SML was investigated in the present study. Characterizations of laterite were examined by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, inductively coupled plasma mass spectrometry (ICP-MS, and total carbon analysis. The optimum conditions for removal of Cu2+ by adsorption using SML were systematically studied and found as pH 6, contact time 90 min, adsorbent dosage 5 mg/mL, and ionic strength 10 mM NaCl. The equilibrium concentration of copper ions was measured by flame atomic absorption spectrometry (F-AAS. Surface modification of laterite by anionic surfactant sodium dodecyl sulfate (SDS induced a significant increase of the removal efficiency of Cu2+. The surface modifications of laterite by preadsorption of SDS and sequential adsorption of Cu2+ were also evaluated by XRD and FT-IR. The adsorption of Cu2+ onto SML increases with increasing NaCl concentration from 1 to 10 mM, but at high salt concentration this trend is reversed because desorption of SDS from laterite surface was enhanced by increasing salt concentration. Experimental results of Cu2+/SML adsorption isotherms at different ionic strengths can be represented well by a two-step adsorption model. Based on adsorption isotherms, surface charge effects, and surface modification, we suggest that the adsorption mechanism of Cu2+ onto SML was induced by electrostatic attraction between Cu2+ and the negatively charged SML surface and nonelectrostatic interactions between Cu2+ and organic substances in the laterite.

  4. Wormlike micelles in mixed amino acid surfactant/nonionic surfactant aqueous systems and the effect of added electrolytes.

    Science.gov (United States)

    Shrestha, Rekha Goswami; Rodriguez-Abreu, Carlos; Aramaki, Kenji

    2009-01-01

    The formation of viscoelastic wormlike micelles in mixed amino acid surfactant/nonionic surfactant aqueous systems in the presence of different counterions and salts is reported, and the effects of the different electrolytes on the rheological behavior are discussed. N-dodecanoylglutamic acid (LAD) is neutralized with biologically relevant L-lysine and L-arginine to obtain anionic surfactants (LAD-Lys2, LAD-Arg2) which form aqueous micellar solutions at 25 degrees C. Addition of a nonionic surfactant, tri-ethyleneglycol mono n-tetradecyl ether (C14EO3), to the aqueous solutions of both LAD-Lys2 and LAD-Arg2 causes the zero-shear viscosity (eta(0)) to increase with C14EO3 concentration gradually at first, and then sharply, indicating one-dimensional growth of the aggregates and eventual formation of entangled wormlike micelles. Further addition of C14EO3 ultimately leads to phase separation of liquid crystals. Such a phase separation, which limits the maximum attainable viscosity, takes place at lower C14EO3 concentrations for LAD-Lys2 compared to LAD-Arg2 systems. It was found that the rheological behavior of micellar solutions is significantly affected by the addition of Na+X(-) salts (X = Cl(-), Br(-), I(-), NO3(-)). The maximum viscosities obtained for the systems with added salt are all higher than that of the salt-free system, and the onset of wormlike micelle formation shift towards lower nonionic surfactant concentrations upon addition of electrolyte. The maximum attainable thickening effect of anions increases in the order NO3(-)>I(-)>Br(-)>Cl(-). The effect of temperature was also investigated. Phase separation takes place at certain temperature, which depends on the type of anion in the added salt, and decreases in the order I(-)>NO3(-)>Br(-) approximately equal Cl(-), in agreement with Hofmeister's series in terms of amphiphile solubility. The thermoresponsive rheological behavior was also found to be highly dependent on the type of anion, and anomalous

  5. 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 a

  6. Critical interaction strength for surfactant-induced mesomorphic structures in polymer-surfactant systems

    NARCIS (Netherlands)

    Ruokolainen, J.; Torkkeli, M.; Serimaa, R.; Vahvaselka, S.; Saariaho, M.; ten Brinke, G.; Ikkala, O.; Vahvaselkä, Sakari

    1996-01-01

    The critical interaction strength to induce mesomorphic structures in flexible polymers by complexing with surfactants is determined by using surfactants with different hydrogen-bonding strengths;. Two essential requirements have to be satisfied: (i) the association has to be strong enough, otherwis

  7. Surfactant Enhanced Electroremediation of Phenanthrene

    Institute of Scientific and Technical Information of China (English)

    佘鹏; 杨建刚; 等

    2003-01-01

    Removal of hydrophobic organic contaminants(HOCs) form soil of low permeability by electroremediation was investigated by using phenanthrene and kaolinite as a model system.Tween 80 was added into the purging solution in order to enhance the solubility of phenanthrene.The effects of pH on the adsorption of phenanthrene and Tween 80 on kaolinite and the magnitude of ζ-potential of kaolinite were examined,respectively.The effects of electric field strength indicated by electric current on the electroremediation behavior,including the pH of purging solution,the conductivity,phenanthrene concentration and flow rate of effluent,were experimentally investigated,repectively,In case of an electric field of 25mA applied for 72 hours,over 90% of phenanthrene was removed from 424g(dry mass)of kaolinite at an energy consumption of 0.148kW.h.The experimental results described in present study show that the addition of surfactant into purging solution greatly enhances the removel of HOCs by electroremediation.

  8. Effects of Ionic Surfactants on Bacterial Luciferase and α-Amylase%离子型表面活性剂对荧光素酶和α-脂肪酶的影响

    Institute of Scientific and Technical Information of China (English)

    闫桑田; 李安; 郑浩; 罗明芳; 邢新会

    2009-01-01

    In order to study the effects of ionic surfactants on bacterial luciferase, the cationic surfactant dodecyl-trimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen. For comparison with bacterial luciferase, α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites. After the enzymes were treated with the surfactants, the catalytic properties of bacterial luciferase and a-amylase were assayed, and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure. The results showed that when the DTAB concentration was low, the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase and a-amylase. On the other hand, the anionic surfactant SDS did not alter the enzymatic activity. The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction, which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low. However, at high cationic surfactant concentration, the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins, leading to the loss of enzymatic activities.

  9. Effect of anionic surfactants on the process of Fenton degradation of methyl orange.

    Science.gov (United States)

    Yang, C W; Wang, D

    2009-01-01

    Fenton process has been shown to be very successful to remove dyes from water. However, the influence of other constituents in dyeing industry wastewater, such as Sodium Dodecyl Sulphate (SDS) surfactants, has not been investigated. In this study, the effect of SDS surfactant on the kinetics of Methyl Orange degradation undergoing Fenton process was investigated. Results show that Methyl Orange degradation rate decreased as SDS concentration increased, which was attributed to the consumption of hydroxyl radicals (OH) by surfactants and the formation of Methyl Orange-SDS complex. No evidence was found that the Methyl Orange degradation pathway was affected by the presence of SDS. The kinetics modelling indicates the reaction was the first-order reaction to Methyl Orange.

  10. Effect of surfactants and temperature on germination and vegetative growth of Beauveria bassiana

    Directory of Open Access Journals (Sweden)

    Lizzy A. Mwamburi

    2015-03-01

    Full Text Available Three non-ionic surfactants: Tween20, Tween80 and Breakthru® were screened for their effects on spore germination and mycelial growth rates and for their influence on three isolates of Beauveria bassianaspore germination at various temperatures. Tween20 and Tween80 were compatible with all the B. bassiana isolates in the germination studies, but inhibited germination at higher surfactant concentrations, irrespective of the conidial concentrations. Breakthru® had an inhibitory effect on germination even at the lowest concentration of 0.1% on all the B. bassiana isolates. The effects of the surfactants on spore germination did not correspond with their effects on colony growth. Conidial viability within the same formulation declined significantly with increases in temperature, irrespective of the surfactant. The optimal temperature for conidial germination of B. bassiana isolates was approximately 25 °C with an upper limit at 30 °C. Isolate 7320 was identified as the least affected by the different surfactants. This isolate was able to germinate rapidly in a broad temperature range of 25–30 °C after 24 h, this characteristic being an essential factor in controlling house fly populations in poultry houses.

  11. Effect of surfactants and temperature on germination and vegetative growth of Beauveria bassiana.

    Science.gov (United States)

    Mwamburi, Lizzy A; Laing, Mark D; Miller, Ray M

    2015-03-01

    Three non-ionic surfactants: Tween20, Tween80 and Breakthru (®) were screened for their effects on spore germination and mycelial growth rates and for their influence on three isolates of Beauveria bassiana spore germination at various temperatures. Tween20 and Tween80 were compatible with all the B. bassiana isolates in the germination studies, but inhibited germination at higher surfactant concentrations, irrespective of the conidial concentrations . Breakthru (®) had an inhibitory effect on germination even at the lowest concentration of 0.1% on all the B. bassiana isolates. The effects of the surfactants on spore germination did not correspond with their effects on colony growth. Conidial viability within the same formulation declined significantly with increases in temperature, irrespective of the surfactant. The optimal temperature for conidial germination of B. bassiana isolates was approximately 25 °C with an upper limit at 30 °C. Isolate 7320 was identified as the least affected by the different surfactants. This isolate was able to germinate rapidly in a broad temperature range of 25-30 °C after 24 h, this characteristic being an essential factor in controlling house fly populations in poultry houses.

  12. Selection of surfactant in remediation of DDT-contaminated soil by comparison of surfactant effectiveness.

    Science.gov (United States)

    Guo, Ping; Chen, Weiwei; Li, Yueming; Chen, Tao; Li, Linhui; Wang, Guanzhu

    2014-01-01

    With an aim to select the most appropriate surfactant for remediation of DDT-contaminated soil, the performance of nonionic surfactants Tween80, TX-100, and Brij35 and one anionic surfactant sodium dodecyl benzene sulfonate (SDBS) in enhancement of DDT water solubility and desorption of DDT from contaminated soil and their adsorption onto soil and ecotoxicities were investigated in this study. Tween80 had the highest solubilizing and soil-washing ability for DDT among the four experimental surfactants. The adsorption loss of surfactants onto soil followed the order of TX-100 > Tween80 > Brij35 > SDBS. The ecotoxicity of Tween80 to ryegrass (Lolium perenne L.) was lowest. The overall performance considering about the above four aspects suggested that Tween80 should be selected for the remediation of DDT-contaminated soil, because Tween80 had the greatest solubilizing and soil-washing ability for DDT, less adsorption loss onto soil, and the lowest ecotoxicity in this experiment.

  13. Microemulsion-based lycopene extraction: Effect of surfactants, co-surfactants and pretreatments.

    Science.gov (United States)

    Amiri-Rigi, Atefeh; Abbasi, Soleiman

    2016-04-15

    Lycopene is a potent antioxidant that has received extensive attention recently. Due to the challenges encountered with current methods of lycopene extraction using hazardous solvents, industry calls for a greener, safer and more efficient process. The main purpose of present study was application of microemulsion technique to extract lycopene from tomato pomace. In this respect, the effect of eight different surfactants, four different co-surfactants, and ultrasound and enzyme pretreatments on lycopene extraction efficiency was examined. Experimental results revealed that application of combined ultrasound and enzyme pretreatments, saponin as a natural surfactant, and glycerol as a co-surfactant, in the bicontinuous region of microemulsion was the optimal experimental conditions resulting in a microemulsion containing 409.68±0.68 μg/glycopene. The high lycopene concentration achieved, indicates that microemulsion technique, using a low-cost natural surfactant could be promising for a simple and safe separation of lycopene from tomato pomace and possibly from tomato industrial wastes.

  14. Carriers recombination processes in charge trapping memory cell by simulation

    Institute of Scientific and Technical Information of China (English)

    Song Yun-Cheng; Liu Xiao-Yan; Du Gang; Kang Jin-Feng; Han Ru-Qi

    2008-01-01

    We have evaluated the effects of recombination processes in a charge storage layer, either between trapped electrons and trapped holes or between trapped carriers and free carriers, on charge trapping memory cell's performances by numerical simulation. Recombination is an indispensable mechanism in charge trapping memory. It helps charge convert process between negative and positive charges in the charge storage layer during charge trapping memory programming/erasing operation. It can affect the speed of programming and erasing operations.

  15. 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.

  16. Solubilization of octane in cationic surfactant-anionic polymer complexes: effect of polymer concentration and temperature.

    Science.gov (United States)

    Zhang, Hui; Deng, Lingli; Zeeb, Benjamin; Weiss, Jochen

    2015-07-15

    Polymers may alter the ability of oppositely charged surfactant micelles to solubilize hydrophobic molecules depending on surfactant-polymer interactions. This study was conducted to investigate the effects of polymer concentration and temperature on the solubilization thermodynamics of an octane oil-in-water emulsion in mixtures of an anionic polymer (carboxymethyl cellulose) and cationic cetyltrimethylammonium bromide (CTAB) surfactant micelles using isothermal titration calorimetry (ITC). Results showed that the CTAB binding capacity of carboxymethyl cellulose increased with increasing temperature from 301 to 323 K, and correspondingly the thermodynamic behavior of octane solubilization in CTAB micelles, either in the absence or presence of polymer, was found to depend on temperature. The addition of carboxymethyl cellulose caused the solubilization in CTAB micelles to be less endothermic, and increased the solubilization capacity. Based on the phase separation model, the solubilization was suggested to be mainly driven by enthalpy gains. Results suggest that increasing concentrations of the anionic polymer gave rise to a larger Gibbs energy decrease and a larger unfavorable entropy increase for octane solubilization in cationic surfactant micelles.

  17. The effect of nanoparticle surfactant polarization on trapping depth of vegetable insulating oil-based nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian, E-mail: lijian@cqu.edu.cn; Du, Bin; Wang, Feipeng; Yao, Wei; Yao, Shuhan

    2016-02-05

    Nanoparticles can generate charge carrier trapping and reduce the velocity of streamer development in insulating oils ultimately leading to an enhancement of the breakdown voltage of insulating oils. Vegetable insulating oil-based nanofluids with three sizes of monodispersed Fe{sub 3}O{sub 4} nanoparticles were prepared and their trapping depths were measured by thermally stimulated method (TSC). It is found that the nanoparticle surfactant polarization can significantly influence the trapping depth of vegetable insulating oil-based nanofluids. A nanoparticle polarization model considering surfactant polarization was proposed to calculate the trapping depth of the nanofluids at different nanoparticle sizes and surfactant thicknesses. The results show the calculated values of the model are in a fairly good agreement with the experimental values. - Highlights: • Three different sized Fe{sub 3}O{sub 4} vegetable-oil based nanofluids was successfully prepared. • The trapping depth of the Fe{sub 3}O{sub 4} nanofluids was investigated. • A new model considering surfactant polarization was proposed to calculate the trapping depth of the nanofluids.

  18. Multivariate design for the evaluation of lipid and surfactant composition effect for optimisation of lipid nanoparticles.

    Science.gov (United States)

    Martins, Susana; Tho, Ingunn; Souto, Eliana; Ferreira, Domingos; Brandl, Martin

    2012-04-11

    Physicochemical properties of lipid nanoparticles (LN), such as size, size distribution and surface charge, have a major influence both, on in vitro stability and delivery of the incorporated drug in vivo. With the purpose of understanding how these properties are influenced by variations of LN composition (e.g. lipid and surfactant type and concentration) 2(2) factorial designs with centre point were applied for several types of lipids and surfactants in the present study. Tested factors and levels were the type and concentration of lipid (cetyl palmitate, Dynasan 114 and Witepsol E85) at the concentrations of 5%, 10% and 15%, in combination with type and concentration of surfactant (polysorbate 20, 40, 60 and 80 and poloxamer 188 and 407) at concentrations of 0.8%, 1.2% and 2.0%. Responses measured within the design space were the mean size and polydispersity index (photon correlation spectroscopy), content of microparticles (optical single particle sizing), macroscopic appearance, pH and zeta potential on the day of production, 1 and 2 years after production. Multivariate evaluation and modelling were performed starting with a principal component analysis (PCA) and followed by partial least square regression analysis (PLS) to assess both qualitative and quantitative influence of the investigated factors in the LN. Our study showed that both, lipid and surfactant concentration and the type of surfactant are crucial parameters for the particle size of the LN prepared by high pressure homogenisation (HPH). For LN stability during 2 years both, lipid and surfactant types and concentrations were identified as the most relevant parameters. Among the surfactants most suitable for producing LN with small sizes were the polysorbates and the lipid yielding best storage stability was cetyl palmitate. Furthermore, the models allowed the prediction of the mean size of LN that could be achieved with a certain lipid/surfactant combination and concentration. The obtained

  19. In situ grown nano-architectures of Co₃O₄ on Ni-foam for charge storage application

    Indian Academy of Sciences (India)

    G RAJESHKHANNA; EDIGA UMESHBABU; G RANGA RAO

    2017-02-01

    Nanostructured Co₃O₄ on Ni-foam has been synthesized with diverse morphologies, high surface area and porosity by employing different surfactants under hydrothermal conditions and subsequent calcination. The surfactants strongly influence the physicochemical properties of cobalt oxide samples. The cobalt oxide grown on Ni-foam without surfactant had flower-like morphology. However, cobalt oxides synthesized by using cationic (CTAB) and non-ionic (Triton X-100) surfactants showed flake-like morphology, but the spatial arrangement of flakes was found to be different in both the samples. The surfactant-assisted cobalt oxide showed average crystallite size of ∼6.6–9.8 nm, surface area of 60–80 m2g−1 and porosity (pore diameter ∼3.8 nm). These samples were found to perform better as charge storage electrode materials. The specific capacitance values of cationic and non-ionic surfactant-assisted cobalt oxide materials, at a current density of1.0 A g−1, were 1820 and 806 F g−1, respectively, compared to 288 F g−1 of cobalt oxide prepared without surfactant. They also showed excellent capacity retention for over 3000 charge-discharge cycles at higher current densities. The difference in the capacitance values of cationic and non-ionic surfactant-assisted cobalt oxide is due to the difference in the flake arrangement.

  20. INTERACTION BETWEEN SURFACTANT AND COLLAGEN

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Interactions of collagen fibres (made from Beef Achilles tendons )with sodium dodecyl sulfate (SDS),sodium dodecylbenzene sulfonate (SDBS),cetylpyridinium bromide(CPB)and Igepal CA-720 were studied.Sorptions isotherms of all ionic surfactants under different reaction conditions were found out.At suitable conditions S-isotherms were obtained,while under isoeletric conditions isotherms were logaritmic.Igepal had no sorption.The interaction of surfactants with collagen is connected with its mass changes. Changes depend on reaction conditions,namely pH and ionic strenght of reaction solution.Degree of swelling(αm)was used for the description of these changes.At pH=3,in absence SDBS and under low ionic strenghts,a high swelling was attained.An addition of SDBS to reaction mixture led to vigerous deswelling and when the bound amount of SDBS reached about 1 mmol.g-1 αm became independent on a futher bound SDBS.With higher ionic strenghts αm was independent on the equilibrium bound amount of SDBS.Under isoeletric conditions changes of αm were markedly smaller than in acid region and had the opposite character.%研究了十二烷基硫酸钠(SDS)、二十烷基苯磺酸钠(SDBS)、溴化十六烷基吡啶翁(CPB)和Igepal CA-720等表面活性剂与胶原(来源于牛跟腱)间的相互作用.发现了不同的反应条件下,上述离子性表面活性剂的吸附等温线,得到了适当条件下的吸附等温线,同时发现在等电条件下等温线呈对数关系,Igepal没有吸附.表面活性剂与胶原的作用情况与其质量的变化是相互关联的,这种变化取决于反应条件,即pH值和反应溶液中的离子强度,胶原的膨胀程度(am)被用来描述这种变化.在pH3.0,无SDBS存在且在低的离子强度下,胶原得到了大的膨胀:加入SDBS将会导致强烈的消肿作用,并且当胶原对SDBS的结合量达到1mmol/g时,am的值将不再随SDBS结合量的进一步增加而变化.在高的离子

  1. Alterations of alveolar type II cells and intraalveolar surfactant after bronchoalveolar lavage and perfluorocarbon ventilation. An electron microscopical and stereological study in the rat lung

    Directory of Open Access Journals (Sweden)

    Burkhardt Wolfram

    2007-06-01

    Full Text Available Abstract Background Repeated bronchoalveolar lavage (BAL has been used in animals to induce surfactant depletion and to study therapeutical interventions of subsequent respiratory insufficiency. Intratracheal administration of surface active agents such as perfluorocarbons (PFC can prevent the alveolar collapse in surfactant depleted lungs. However, it is not known how BAL or subsequent PFC administration affect the intracellular and intraalveolar surfactant pool. Methods Male wistar rats were surfactant depleted by BAL and treated for 1 hour by conventional mechanical ventilation (Lavaged-Gas, n = 5 or partial liquid ventilation with PF 5080 (Lavaged-PF5080, n = 5. For control, 10 healthy animals with gas (Healthy-Gas, n = 5 or PF5080 filled lungs (Healthy-PF5080, n = 5 were studied. A design-based stereological approach was used for quantification of lung parenchyma and the intracellular and intraalveolar surfactant pool at the light and electron microscopic level. Results Compared to Healthy-lungs, Lavaged-animals had more type II cells with lamellar bodies in the process of secretion and freshly secreted lamellar body-like surfactant forms in the alveoli. The fraction of alveolar epithelial surface area covered with surfactant and total intraalveolar surfactant content were significantly smaller in Lavaged-animals. Compared with Gas-filled lungs, both PF5080-groups had a significantly higher total lung volume, but no other differences. Conclusion After BAL-induced alveolar surfactant depletion the amount of intracellularly stored surfactant is about half as high as in healthy animals. In lavaged animals short time liquid ventilation with PF5080 did not alter intra- or extracellular surfactant content or subtype composition.

  2. Exogenous surfactant application in a rat lung ischemia reperfusion injury model: effects on edema formation and alveolar type II cells

    Directory of Open Access Journals (Sweden)

    Richter Joachim

    2008-01-01

    peribronchovascular edema. Morphological changes of alveolar type II cells due to I/R are not affected by surfactant treatment. The beneficial effects of exogenous surfactant therapy are related to the intraalveolar activity of the exogenous surfactant.

  3. Foaming behaviour of polymer-surfactant solutions

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes-MartInez, Alfredo [Departamento de Investigacion en PolImeros y Materiales, Universidad de Sonora, Apartado Postal 130, 83000 Hermosillo, Sonora (Mexico); Maldonado, Amir [Departamento de Fisica, Universidad de Sonora, Apartado Postal 1626, 83000 Hermosillo, Sonora (Mexico)

    2007-06-20

    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.

  4. 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.

  5. 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.

  6. Surfactant effects on SF6 hydrate formation.

    Science.gov (United States)

    Lee, Bo Ram; Lee, Ju Dong; Lee, Hyun Ju; Ryu, Young Bok; Lee, Man Sig; Kim, Young Seok; Englezos, Peter; Kim, Myung Hyun; Kim, Yang Do

    2009-03-01

    Sulfur hexafluoride (SF(6)) has been widely used in a variety of industrial processes, but it is one of the most potent greenhouse gases. For this reason, it is necessary to separate or collect it from waste gas streams. One separation method is through hydrate crystal formation. In this study, SF(6) hydrate was formed in aqueous surfactant solutions of 0.00, 0.01, 0.05, 0.15 and 0.20 wt% to investigate the effects of surfactants on the hydrate formation rates. Three surfactants, Tween 20 (Tween), sodium dodecyl sulfate (SDS) and linear alkyl benzene sulfonate (LABS), were tested in a semi-batch stirred vessel at the constant temperature and pressures of 276.2 K and 0.78 MPa, respectively. All surfactants showed kinetic promoter behavior for SF(6) hydrate formation. It was also found that SF(6) hydrate formation proceeded in two stages with the second stage being the most rapid. In situ Raman spectroscopy analysis revealed that the increased gas consumption rate with the addition of surfactant was possibly due to the increased gas filling rate in the hydrate cavity.

  7. 2-DE using hemi-fluorinated surfactants.

    Science.gov (United States)

    Starita-Geribaldi, Mireille; Thebault, Pascal; Taffin de Givenchy, Elisabeth; Guittard, Frederic; Geribaldi, Serge

    2007-07-01

    The synthesis of hemi-fluorinated zwitterionic surfactants was realized and assessed for 2-DE, a powerful separation method for proteomic analysis. These new fluorinated amidosulfobetaine (FASB-p,m) were compared to their hydrocarbon counterparts amidosulfobetaine (ASB-n) characterized by a hydrophilic polar head, a hydrophobic and lipophilic tail, and an amido group as connector. The tail of these FASB surfactants was in part fluorinated resulting in the modulation of its lipophilicity (or oleophobicity). Their effect on the red blood cell (RBC) membrane showed a specific solubilization depending on the length of the hydrophobic part. A large number of polypeptide spots appeared in the 2-DE patterns by using FASB-p,m. The oleophobic character of these surfactants was confirmed by the fact that Band 3, a highly hydrophobic transmembrane protein, was not solubilized by these fluorinated structures. The corresponding pellet was very rich in Band 3 and could then be solubilized by using a strong detergent such as amidosulfobetaine with an alkyl tail containing 14 carbon atoms (ASB-14). Thus, these hemi-fluorinated surfactants appeared as powerful tools when used at the first step of a two-step solubilization strategy using a hydrocarbon homologous surfactant in the second step.

  8. 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.

  9. Structural studies of the formation of lipoplexes between siRNA and selected bis-imidazolium gemini surfactants.

    Science.gov (United States)

    Andrzejewska, W; Pietralik, Z; Skupin, M; Kozak, M

    2016-10-01

    Dicationic (gemini) surfactants are agents that can be used for the preparation of stable complexes of nucleic acids, particularly siRNA for therapeutic purposes. In this study, we demonstrated that bis-imidazolium gemini surfactants with variable lengths of dioxyalkyl linker groups (from dioxyethyl to dioxydodecyl) and dodecyl side chains are excellent for the complexation of siRNA. All of these compounds effectively complexed siRNA in a charge ratio range (p/n) of 1.5-10. The low resolution structure of siRNA oligomers was characterised by small angle scattering of synchrotron radiation (SR-SAXS) and ab initio modelling. The structures of the formed complexes were also analysed using SR-SAXS, circular dichroism studies and electrophoretic mobility tests. The most promising agents for complexation with siRNA were the surfactants that contained dioxyethyl and dioxyhexyl spacer groups.

  10. Separation of cationic analytes by nonionic micellar electrokinetic chromatography using polyoxyethylene lauryl ether surfactants with different polyoxyethylene length.

    Science.gov (United States)

    Quirino, Joselito P; Kato, Masaru

    2014-09-01

    Although nonionic micellar electrokinetic chromatography is used for the separation of charged compounds that are not easily separated by capillary zone electrophoresis, the effect of the hydrophilic moiety of the nonionic surfactant has not been studied well. In this study, the separation of ultraviolet-absorbing amino acids was studied in electrokinetic chromatography using neutral polyoxyethylene lauryl ether surfactants (Adekatol) in the separation solution. The effect of the polyethylene moiety (the number of repeating units was from 6.5 to 50) of the hydrophobic test amino acids (methionine, tryptophan, and tysorine) was studied using a 10 cm effective length capillary. The separation mechanism was based on hydrophobic as well as hydrogen bonding interactions at the micellar surface, which was made of the polyoxyethylene moiety. The length of the polyoxyethylene moiety of the surfactants was not important in nonionic micellar electrokinetic chromatography mode.

  11. Ki-67 acts as a biological surfactant to disperse mitotic chromosomes.

    Science.gov (United States)

    Cuylen, Sara; Blaukopf, Claudia; Politi, Antonio Z; Müller-Reichert, Thomas; Neumann, Beate; Poser, Ina; Ellenberg, Jan; Hyman, Anthony A; Gerlich, Daniel W

    2016-07-14

    Eukaryotic genomes are partitioned into chromosomes that form compact and spatially well-separated mechanical bodies during mitosis. This enables chromosomes to move independently of each other for segregation of precisely one copy of the genome to each of the nascent daughter cells. Despite insights into the spatial organization of mitotic chromosomes and the discovery of proteins at the chromosome surface, the molecular and biophysical bases of mitotic chromosome structural individuality have remained unclear. Here we report that the proliferation marker protein Ki-67 (encoded by the MKI67 gene), a component of the mitotic chromosome periphery, prevents chromosomes from collapsing into a single chromatin mass after nuclear envelope disassembly, thus enabling independent chromosome motility and efficient interactions with the mitotic spindle. The chromosome separation function of human Ki-67 is not confined within a specific protein domain, but correlates with size and net charge of truncation mutants that apparently lack secondary structure. This suggests that Ki-67 forms a steric and electrostatic charge barrier, similar to surface-active agents (surfactants) that disperse particles or phase-separated liquid droplets in solvents. Fluorescence correlation spectroscopy showed a high surface density of Ki-67 and dual-colour labelling of both protein termini revealed an extended molecular conformation, indicating brush-like arrangements that are characteristic of polymeric surfactants. Our study thus elucidates a biomechanical role of the mitotic chromosome periphery in mammalian cells and suggests that natural proteins can function as surfactants in intracellular compartmentalization.

  12. The role of surfactants in Köhler theory reconsidered

    Directory of Open Access Journals (Sweden)

    R. Sorjamaa

    2004-05-01

    Full Text Available Atmospheric aerosol particles typically consist of inorganic salts and organic material. The inorganic compounds as well as their hygroscopic properties are well defined, but the effect of organic compounds on cloud droplet activation is still poorly characterized. The focus of the present study is in the organic compounds that are surface active i.e. they concentrate on droplet surface and decrease droplet surface tension. Gibbsian surface thermodynamics were used to find out how partitioning in binary and ternary aqueous solutions affects the droplet surface tension and the droplet bulk concentration in droplets large enough to act as cloud condensation nuclei. Sodium dodecyl sulfate was used as a model compound together with sodium chloride to find out the effect the correct evaluation of surfactant partitioning has on the solute effect (Raoult effect. While the partitioning is known to lead to higher surface tension compared to a case in which partitioning is neglected, the present results show that the partitioning also alters the solute effect, and that the change is large enough to further increase the critical supersaturation and hence decrease the droplet activation. The fraction of surfactant partitioned to droplet surface increases with decreasing droplet size, which suggests that surfactants might enhance the activation of larger particles relatively more thus leading to less dense clouds. Cis-pinonic acid-ammonium sulfate aqueous solution was studied in order to relate the partitioning to more realistic atmospheric situation and to find out the combined effects of dissolution and partitioning behaviour. The results show that correct partitioning consideration alters the shape of the Köhler curve when compared to a situation in which the partitioning is neglected either completely or in the Raoult effect.

  13. Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

    Science.gov (United States)

    Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

  14. Interaction of Fluorocarbon Containing Hydrophobically Modified Polyelectrolyte with Nonionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    GUO,Jin-Feng(郭金峰); ZHUANG,Dong-Qing(庄东青); ZHOU,Hui(周晖); ZHANG,Yun-Xiang(章云祥)

    2002-01-01

    The interaction of fluorocarbon containing hydrophobically modified polyelectrolyte (FMPAANa) with two kinds of nonionic surfactants (hydrogenated and fluorinated) in a semidilute (0.5 wt% ) aqueous solution had been studied by rheological measurements. Association behavior was found in both systems. The hydrophobic interaction of FMPAANa with fluorinated surfactant (FC171) is much stronger than that with hydrogenated surfactant (NP7.5) at low surfactant concentrations. The interaction is strengthened by surfactants being added for the density of active junctions increased. Whereas distinct phenomena for FC171 and NP7. 5 start to be found as the surfactants added over their respective certain concentration. The interaction of polyelectrolyte with fluorinated surfactant increases dramatical ly while that with hydrogenated surfactant decreases.

  15. Fullerene surfactants and their use in polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. 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.

  17. Natural surfactants used in cosmetics: glycolipids.

    Science.gov (United States)

    Lourith, N; Kanlayavattanakul, M

    2009-08-01

    Cosmetic surfactant performs detergency, wetting, emulsifying, solubilizing, dispersing and foaming effects. Adverse reactions of chemical synthesis surfactant have an effect on environment and humans, particularly severe in long term. Biodegradability, low toxicity and ecological acceptability which are the benefits of naturally derived surfactant that promises cosmetic safety are, therefore, highly on demand. Biosurfactant producible from microorganisms exhibiting potential surface properties suitable for cosmetic applications especially incorporate with their biological activities. Sophorolipids, rhamnolipids and mannosylerythritol lipids are the most widely used glycolipids biosurfactant in cosmetics. Literatures and patents relevant to these three glycolipids reviewed were emphasizing on the cosmetic applications including personal care products presenting the cosmetic efficiency, efficacy and economy benefits of glycolipids biosurfactant.

  18. Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide gemini surfactants as novel corrosion inhibitors for mild steel in formic acid

    Directory of Open Access Journals (Sweden)

    Mohammad Mobin

    2012-12-01

    Full Text Available Gemini surfactants, butanediyl 1,4-bis(dimethyl cetylammonium bromide, pentanediyl 1,5 - bis (dimethyl cetylammonium bromide and hexanediyl 1,6 - bis (dimethyl cetylammonium bromide from Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide series were synthesized in laboratory and were characterized by using Nuclear Magnetic Resonance (NMR spectroscopy. The surfactants were tested as corrosion inhibitors for mild steel in 20% formic acid. The influence of surfactants on mild steel corrosion inhibition was investigated by measuring the corrosion rate of mild steel in their absence and presence by weight loss measurements, solvent analysis of iron ions into the test solution and potentiodynamic polarization measurements. The surface morphology of the corroded steel samples in presence and absence of surfactants was evaluated by using Scanning Electron Microscopy (SEM. The synthesized gemini surfactants performed as excellent corrosion inhibitor, the inhibition efficiency (IE being in the range of 76.66-97.41%. The IE of surfactants is slightly affected by the spacer length. The IE increased with increase in surfactant concentration and temperature. The adsorption of gemini surfactants on the steel surface was found to obey Langmuir adsorption isotherm. The results of the potentiodynamic polarization studies are consistent with the results of weight loss studies.

  19. Surfactant-Polymer Interaction for Improved Oil Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Mohanty, Kishore K.

    2002-01-07

    The goal of this research was to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, oil solubility in the displacing fluid and mobility control. Surfactant-polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation and viscous/heterogeneity fingering.

  20. Dynamic Study of Gemini Surfactant and Single-chain Surfactant at Air/Water Interface

    Institute of Scientific and Technical Information of China (English)

    Yi Jian CHEN; Gui Ying XU; Shi Ling YUAN; Hai Ying SUN

    2005-01-01

    Molecular dynamics (MD) simulation are used to study the properties of gemini surfactant of ethyl-α,ω-bis(dodecyldimethylammonium bromide) (C12C2C12) and dodecyltrimethylammonium bromide (DTAB) at the air/water interface, respectively. In the two systems,the surfactant concentrations are both 28 wt. %, and other conditions are also the same. After reaching the thermodynamic equilibrium, the concentration profiles, the radial distributions functions (RDF) and the mean squared displacement (MSD) are investigated. Theresults reveal that the surface activity of C12C2C12 suffactant is higher than DTAB surfactant.

  1. 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

  2. Two-dimensional photonic crystal surfactant detection.

    Science.gov (United States)

    Zhang, Jian-Tao; Smith, Natasha; Asher, Sanford A

    2012-08-07

    We developed a novel two-dimensional (2-D) crystalline colloidal array photonic crystal sensing material for the visual detection of amphiphilic molecules in water. A close-packed polystyrene 2-D array monolayer was embedded in a poly(N-isopropylacrylamide) (PNIPAAm)-based hydrogel film. These 2-D photonic crystals placed on a mirror show intense diffraction that enables them to be used for visual determination of analytes. Binding of surfactant molecules attaches ions to the sensor that swells the PNIPAAm-based hydrogel. The resulting increase in particle spacing red shifts the 2-D diffracted light. Incorporation of more hydrophobic monomers increases the sensitivity to surfactants.

  3. Influence of surfactant concentration on nanohydroxyapatite growth

    Indian Academy of Sciences (India)

    D Gopi; J Indira; S Nithiya; L Kavitha; U Kamachi Mudali; K Kanimozhi

    2013-10-01

    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 of the surfactant was tuned in such a way that the desired HAP nanostructures were obtained. The resultant powders were sintered at 900 °C in order to obtain phase pure HAP particles. The results obtained by Fourier transform infrared spectroscopy (FT–IR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques have substantiated the formation of nanosized HAP spheres and fibres.

  4. VESICLE-SURFACTANT INTERACTIONS - EFFECTS OF ADDED SURFACTANTS ON THE GEL TO LIQUID-CRYSTAL TRANSITION FOR 2 VESICULAR SYSTEMS

    NARCIS (Netherlands)

    Blandamer, M.J; Briggs, B.; Cullis, P.M.; Engberts, J.B.F.N.; Kacperska, A.

    1995-01-01

    Interactions of both cationic and anionic surfactants with vesicles formed by dimethyldioctadecylammonium bromide (DOAB) and by sodium didodecylphosphate (DDP) have been probed using differential scanning microcalorimetry. The scans show that the surfactants are incorporated into the vesicle bilayer

  5. Vesicle-Surfactant Interactions : Effects of Added Surfactants on the Gel to Liquid-crystal Transition for Two Vesicular Systems

    NARCIS (Netherlands)

    Blandamer, Michael J.; Briggs, Barbara; Cullis, Paul M.; Engberts, Jan B.F.N.; Kacperska, Anna

    1995-01-01

    Interactions of both cationic and anionic surfactants with vesicles formed by dimethyldioctadecylammonium bromide (DOAB) and by sodium didodecylphosphate (DDP) have been probed using differential scanning microcalorimetry. The scans show that the surfactants are incorporated into the vesicle bilayer

  6. Studying luminescent characteristics of the specific surfactants in various regions of the Baltic Sea

    Science.gov (United States)

    Drozdowska, V.; Darecki, M.; Gutowska, D.; Makuch, P.; Kowalczyk, J.; Strzałkowska, A.; Petelski, T.; Piskozub, J.

    2012-04-01

    The sea surface layer is the interface between the atmosphere and marine environment, where there are a variety of physical, biological and chemical processes that contribute to accumulation and exchange of surface-active-agents (surfactants). At the same time the dynamic properties of the water surface (surface wave spectrum) and fluxes (especially in gas exchange and production of marine aerosol) and even the apparent and real optical properties of seawater are affected by the surfactants gathered on the sea surface. Moreover, the presence of the surface film may restrict the supply of light energy into the depths of the sea. The study was conducted in different regions of the Baltic Sea which also assessed the impact of external environment (estuaries, vicinity of the ports and shipping routs) on the marine environment. The primary scientific objectives were: - to investigate the variability of luminescent properties of surfactants and organic matter contained in the surface film and layer of the sea from the results of spectrophotometric studies. - to find any special surfactants (characterized by luminescent properties) occurring in certain regions of the Baltic. The practical aim was to answer the question whether and to what extent changes in luminescence properties of organic matter contained in the film and the layer depend on the biological activity of the basin and how they affect the water leaving radiance remotely measured over the surface of the sea.

  7. Surfactant phosphatidylcholine metabolism in preterm infants studied with stable isotopes

    NARCIS (Netherlands)

    J.E.H. Bunt (Jan Erik)

    2000-01-01

    textabstractAIM OF THE STUDIES 1. To develop and use a novel method to study surfactant metabolism in preterm and older infants. (chapters 3 and 4). 2. To study endogenous surfactant synthesis in relation to prenatal glucocorticosteroids. (chapters 5 and 6). 3. To study the influence of surfactant t

  8. 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...

  9. Synthesis and Properties of Novel Cationic Maleic Diester Polymerizable Surfactants

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Three new cationic polymerizable surfactants are synthesized by the reaction of alkylmaleic hemiester with glycidyltrimethylammonium chloride. Their structures are confirmed by 1H NMR, IR and elements analysis. The values of CMC and gCMC of these surfactants have been measured. One can obtain nearly monodisperse polystyrene latex by emulsion polymerization using the polymerizable surfactant.

  10. Secondary oil recovery process. [two separate surfactant slugs

    Energy Technology Data Exchange (ETDEWEB)

    Fallgatter, W.S.

    1969-01-14

    Oil recovery by two separate surfactant slugs is greater than for either one alone. One slug contains a surfactant(s) in either oil or water. The other slug contains surfactant(s) in thickened water. The surfactants are sodium petroleum sulfonate (Promor SS20), polyoxyethylene sorbitan trioleate (Tween 85), lauric acid diethanolamide (Trepoline L), and sodium tridecyl sulfate polyglycol ether (Trepenol S30T). The thickener is carboxymethyl cellulose (Hercules CMC 70-S Medium thickener) or polyvinyl alcohol (Du Pont Elvanol 50-42). Consolidated sandstone cores were flooded with water, followed with Hawes crude, and finally salt water (5 percent sodium chloride) which recovered about 67 percent of the crude. A maximum of 27.5 percent of the residual oil was recovered by surfactant(s) in oil or water followed by fresh water, then surfactant(s) plus thickener in water followed by fresh water. Either surfactant slug may be injected first. Individually, each of the surfactant slugs can recover from about 3 to 11 percent less residual oil than their total recovery when used consecutively.

  11. 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.

  12. Influence of ionic surfactants on the flocculation and sorption of palladium and mercury in the aquatic environment.

    Science.gov (United States)

    Turner, Andrew; Xu, Jing

    2008-01-01

    The influence of sub-micellar concentrations of an anionic surfactant (sodium dodecyl sulphate; SDS) and a cationic surfactant (hexadecyl trimethylammonium bromide; HDTMA) on the aquatic behaviour of the strongly complexing metals, Pd(II) and Hg(II), has been investigated. In river water, flocculation of organic complexes of metal was suppressed by SDS but accentuated by HDTMA, effects that are consistent with electrostatic and hydrophobic interactions between ionic surfactants and natural polyelectrolytes. In sea water, flocculation of metal complexes was enhanced by both surfactants because of the shielding and salting effects of inorganic ions on these interactions. Particle surface modification engendered by sorbed surfactant strongly influenced the sorption of Pd and Hg to estuarine particles. Thus, hydrophobically bound SDS enhances the negative charge at the particle surface and favours specific sorption of metal, while specifically sorbed HDTMA enhances the solvency of the particle surface, favouring non-specific sorption of metal complexes. Given the relatively short environmental half-life of SDS, its impacts on strongly complexing metals are predicted to be localised. However, greater stability of HDTMA suggests that its effects on such metals, including enhanced flocculation and sorption, are likely to be more pervasive.

  13. The effects of nonionic surfactants on the tris(2,2'-bipyridyl)ruthenium(II)--tripropylamine electrochemiluminescence system.

    Science.gov (United States)

    Workman, S; Richter, M M

    2000-11-15

    The electrochemistry and electrogenerated chemiluminescence (ECL) of Ru(bpy)3(2+) (bpy = 2,2'-bipyridyl) were studied in the presence of the nonionic surfactants Triton X-100, Thesit, and Nonidet P40. The anodic oxidation of Ru(bpy)3(2+) produces ECL in the presence of tri-n-propylamine in both aqueous and surfactant solutions. Increases in both ECL efficiency (> or =8-fold) and duration of the ECL signal were observed in surfactant media. A shift to lower energies of the Ru(bpy)3(2+) ECL emission by approximately 8 nm was also observed. The one-electron oxidation of Ru(bpy)3(2+) to Ru(bpy)3(3t) occurs at + 1.03 V vs Ag/AgCl in aqueous buffered (0.2 M potassium phosphate) solution as found by square wave voltammetry. This potential did not shift in surfactant systems, indicating that the redshifts in ECL emission are due to stabilization of ligand pi* orbitals in the metal-to-ligand charge-transfer excited state. These results are consistent with hydrophobic interactions between Ru(bpy)3(2+) and the nonionic surfactants.

  14. Rosin Surfactant QRMAE Can Be Utilized as an Amorphous Aggregate Inducer: A Case Study of Mammalian Serum Albumin.

    Science.gov (United States)

    Ishtikhar, Mohd; Chandel, Tajjali Ilm; Ahmad, Aamir; Ali, Mohd Sajid; Al-Lohadan, Hamad A; Atta, Ayman M; Khan, Rizwan Hasan

    2015-01-01

    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.

  15. Tungsten Oxide and Polyaniline Composite Fabricated by Surfactant-Templated Electrodeposition and Its Use in Supercapacitors

    Directory of Open Access Journals (Sweden)

    Benxue Zou

    2014-01-01

    Full Text Available Composite nanostructures of tungsten oxide and polyaniline (PANI were fabricated on carbon electrode by electrocodeposition using sodium dodecylbenzene sulfonate (SDBS as the template. The morphology of the composite can be controlled by changing SDBS surfactant and aniline monomer concentrations in solution. With increasing concentration of aniline in surfactant solution, the morphological change from nanoparticles to nanofibers was observed. The nanostructured WO3/PANI composite exhibited enhanced capacitive charge storage with the specific capacitance of 201 F g−1 at 1.28 mA cm−2 in large potential window of -0.5~ 0.65 V versus SCE compared to the bulk composite film. The capacitance retained about 78% when the sweeping potential rate increased from 10 to 150 mV/s.

  16. The adsorption of biomolecules to multi-walled carbon nanotubes is influenced by both pulmonary surfactant lipids and surface chemistry

    Directory of Open Access Journals (Sweden)

    Yan Bing

    2010-12-01

    Full Text Available Abstract Background During production and processing of multi-walled carbon nanotubes (MWCNTs, they may be inhaled and may enter the pulmonary circulation. It is essential that interactions with involved body fluids like the pulmonary surfactant, the blood and others are investigated, particularly as these interactions could lead to coating of the tubes and may affect their chemical and physical characteristics. The aim of this study was to characterize the possible coatings of different functionalized MWCNTs in a cell free environment. Results To simulate the first contact in the lung, the tubes were coated with pulmonary surfactant and subsequently bound lipids were characterized. The further coating in the blood circulation was simulated by incubating the tubes in blood plasma. MWCNTs were amino (NH2- and carboxyl (-COOH-modified, in order to investigate the influence on the bound lipid and protein patterns. It was shown that surfactant lipids bind unspecifically to different functionalized MWCNTs, in contrast to the blood plasma proteins which showed characteristic binding patterns. Patterns of bound surfactant lipids were altered after a subsequent incubation in blood plasma. In addition, it was found that bound plasma protein patterns were altered when MWCNTs were previously coated with pulmonary surfactant. Conclusions A pulmonary surfactant coating and the functionalization of MWCNTs have both the potential to alter the MWCNTs blood plasma protein coating and to determine their properties and behaviour in biological systems.

  17. Effect of surfactants on the aggregation and sedimentation of zinc oxide nanomaterial in natural water matrices.

    Science.gov (United States)

    Li, Xuankun; Yoneda, Minoru; Shimada, Yoko; Matsui, Yasuto

    2017-03-01

    The wide application of surfactants and engineered nanomaterials (ENMs) in industrial and consumer products lead to the high possibility of their co-presence in natural water environment, making it important to study the effect of surfactants on the environmental behavior and fate of ENMs. In this work, we selected an anionic sodium dodecyl sulfate (SDS) and a nonionic nonylphenol ethoxylate (NPEO, Tergitol NP-9) to study their effects on the aggregation and sedimentation of a 20nm ZnO ENM in different water matrices. The adsorption of SDS and NP-9 by ZnO ENM were fitted with Langmuir model, and the maximum adsorption capacities were 43.73±4.62mg/g and 13.79±1.09 respectively. As the surfactant concentration increased from 0 to 0.030% (m:v), SDS reduced the zeta potential of ZnO ENM from 17.56±2.13 to -27.96±2.59mV, whereas NP-9 did not affect the zeta potential. After a 24-h batch reactor experiment, SDS and NP-9 reduced 93.02% and 80.26% of the aggregate size of ZnO ENM (50mgL(-1)) in maximum at surfactant concentrations≥0.015%. The ZnO ENM was not stable in natural aqueous matrices, mainly because of the relatively high ionic strength. However, surfactants were found to reduce the aggregation and sedimentation of ZnO ENM in six natural water matrices in different degrees. With the presence of 0.030% SDS in tap water, maximum reduction rates of aggregate size and sedimentation were recorded as 69.54% and 26.69%, respectively. The results of this study indicate that the presence of surfactants may alter the behaviors and fate of ENMs in natural water environment.

  18. Degradation of surfactant-modified montmorillonites in HCl

    Energy Technology Data Exchange (ETDEWEB)

    Madejova, Jana, E-mail: jana.madejova@savba.sk [Institute of Inorganic Chemistry, SAS, Dubravska cesta 9, SK-845 36 Bratislava (Slovakia); Palkova, Helena, E-mail: helena.palkova@savba.sk [Institute of Inorganic Chemistry, SAS, Dubravska cesta 9, SK-845 36 Bratislava (Slovakia); Jankovic, Lubos, E-mail: lubos.jankovic@savba.sk [Institute of Inorganic Chemistry, SAS, Dubravska cesta 9, SK-845 36 Bratislava (Slovakia)

    2012-06-15

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

  19. Coarsening of firefighting foams containing fluorinated hydrocarbon surfactants

    Science.gov (United States)

    Kennedy, Matthew J.; Dougherty, John A.; Otto, Nicholas; Conroy, Michael W.; Williams, Bradley A.; Ananth, Ramagopal; Fleming, James W.

    2013-03-01

    Diffusion of gas between bubbles in foam causes growth of large bubbles at the expense of small bubbles and leads to increasing mean bubble size with time thereby affecting drainage. Experimental data shows that the effective diffusivity of nitrogen gas in aqueous film forming foam (AFFF), which is widely used in firefighting against burning liquids, is several times smaller than in 1% sodium dodecyl sulfate (SDS) foam based on time-series photographs of bubble size and weighing scale recordings of liquid drainage. Differences in foam structure arising from foam production might contribute to the apparent difference in the rates of coarsening. AFFF solution produces wetter foam with initially smaller bubbles than SDS solution due in part to the lower gas-liquid surface tension provided by the fluorosurfactants present in AFFF. Present method of foam production generates microbubble foam by high-speed co-injection of surfactant solution and gas into a tube of 3-mm diameter. These results contribute to our growing understanding of the coupling between foam liquid fraction, bubble size, surfactant chemistry, and coarsening. NRC Resident Research Associate at NRL

  20. Undoped Polyaniline/Surfactant Complex for the Corrosion Prevention

    Science.gov (United States)

    Liu, Lo-Min; Levon, Kalle

    1998-01-01

    Due to the strict regulations on the usage of heavy metals as the additives in the coating industries, the search for effective organic corrosion inhibitors in replace of those metal additives has become essential. Electrically conducting polymers have been shown to be effective for corrosion prevention but the poor solubility of these intractable polymers has been a problem. We have explored a polyaniline/4-dodecylphenol complex (PANi/DDPh) to improve the dissolution and it has been shown to be an effective organic corrosion inhibitor. With the surfactant, DDPh, PANi could be diluted into the coatings and the properties of the coatings were affected. Emeraldine base (EB) form of PANi was also found to be oxidized by the hardener. The oxidized form of polyaniline provides improved corrosion protection of metals than that of emeraldine base since the value of the standard electrode potential for the oxidized form of PANi is higher than that of EB. Additionally, the surfactant improves the wet adhesion property between the coating and the metal surface.

  1. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: Roles played by stabilization surfactants of oil droplets

    KAUST Repository

    Lu, Dongwei

    2015-04-07

    Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater. © 2015 American Chemical Society.

  2. Surfactants, not size or zeta-potential influence blood-brain barrier passage of polymeric nanoparticles.

    Science.gov (United States)

    Voigt, Nadine; Henrich-Noack, Petra; Kockentiedt, Sarah; Hintz, Werner; Tomas, Jürgen; Sabel, Bernhard A

    2014-05-01

    Nanoparticles (NP) can deliver drugs across the blood-brain barrier (BBB), but little is known which of the factors surfactant, size and zeta-potential are essential for allowing BBB passage. To this end we designed purpose-built fluorescent polybutylcyanoacrylate (PBCA) NP and imaged the NP's passage over the blood-retina barrier - which is a model of the BBB - in live animals. Rats received intravenous injections of fluorescent PBCA-NP fabricated by mini-emulsion polymerisation to obtain various NP's compositions that varied in surfactants (non-ionic, anionic, cationic), size (67-464nm) and zeta-potential. Real-time imaging of retinal blood vessels and retinal tissue was carried out with in vivo confocal neuroimaging (ICON) before, during and after NP's injection. Successful BBB passage with subsequent cellular labelling was achieved if NP were fabricated with non-ionic surfactants or cationic stabilizers but not when anionic compounds were added. NP's size and charge had no influence on BBB passage and cell labelling. This transport was not caused by an unspecific opening of the BBB because control experiments with injections of unlabelled NP and fluorescent dye (to test a "door-opener" effect) did not lead to parenchymal labelling. Thus, neither NP's size nor chemo-electric charge, but particle surface is the key factor determining BBB passage. This result has important implications for NP engineering in medicine: depending on the surfactant, NP can serve one of two opposite functions: while non-ionic tensides enhance brain up-take, addition of anionic tensides prevents it. NP can now be designed to specifically enhance drug delivery to the brain or, alternatively, to prevent brain penetration so to reduce unwanted psychoactive effects of drugs or prevent environmental nanoparticles from entering tissue of the central nervous system.

  3. Triply Periodic Multiply Continuous Lyotropic Liquid Crystals Derived from Gemini Surfactants

    Science.gov (United States)

    Sorenson, Gregory P.

    A subtle balance of non-covalent interactions directs the self-assembly of small molecule amphiphiles in aqueous media into supramolecular assemblies known as aqueous lyotropic liquid crystals (LLCs). Aqueous LLCs form many intricate, ordered nanoscale morphologies comprising distinct and structurally periodic hydrophobic and hydrophilic domains. Triply periodic multiply continuous (TPMC) LLC morphologies, which exhibit continuous hydrophobic and aqueous domains that percolate in three-dimensions, are of particular interest by virtue of their potentially wide ranging technological applications including advanced membranes for electrical energy storage and utilization, therapeutic delivery, and templates for new organic and inorganic mesoporous materials. However, robust molecular design criteria for amphiphiles that readily form TMPC morphologies are notably lacking in the literature. Recent reports have described the increased propensity for quaternary ammonium and phosphonium gemini surfactants, derived from dimerization of traditional single-tail surfactants at or near the hydrophilic headgroups through a hydrophobic linker, to stabilize TMPC mesophases. The generality of this surfactant design strategy remains untested in other amphiphiles classes bearing different headgroup chemistries. In this thesis, we describe the unusual aqueous LLC phase behavior of series of gemini dicarboxylate amphiphiles as a function of the alkyl tail length, hydrophobic linker length, and the charge-compensating counterion. These dicarboxylate surfactants unexpectedly exhibit a strong propensity to form TPMC LLCs over amphiphile concentration windows as wide as 20 wt% over a temperature range T = 25--100 °C. Through systematic modifications of the length of the hydrophobic linker and alkyl tails, we use small-angle X-ray scattering to demonstrate that these surfactants adopt new LLC mesophases including the first report of a single-gyroid phase (I4132 symmetry) and a new

  4. Multizone Artillery Propelling Charge Studies

    Science.gov (United States)

    1983-05-01

    PROJECT, TASK AREA 4 WORK UNIT NUMBERS IL162618AH80 11. CONTROLLING OFFICE NAME AND ADDRESS US Army Armament Research & Development Command...are affected by the many interrelated components comprising the charge. We have identified areas of concern for bagged multizone charges; studies...B. Brodman DRDAP-LCB-I, D. Spring DRDAR-LCE, R. Walker DRDAR-LCU-CT E. Barrleres R. Davitt DRDAR-CLU-CV C.Mandala E. Moore DRDAR-LCM-E S

  5. Titration procedure for low ethoxylated nonionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Buschmann, N. [Anorganisch-Chemisches Inst., Lehrstuhl fuer Analytische Chemie, Muenster Univ. (Germany); Huelskoetter, F. [Anorganisch-Chemisches Inst., Lehrstuhl fuer Analytische Chemie, Muenster Univ. (Germany)

    1997-01-01

    Highly lipophilic surfactants are frequently used as emulsifiers for preparing oil-in-water emulsions (e.g. coolants lubricants). Typical surfactants used for this purpose are low ethoxylated alcohols and ethoxylated alkylphenols. Due to the low degree of ethoxylation they cannot be analysed by conventional methods. The method described in this article is based on the introduction of an anionic group into the molecule by a derivatization reaction. The reaction product can be determined by conventional titration methods for anionic surfactants without any modification. The use of the new method for other nonionic surfactants like sorbitan esters, (ethoxylated) fatty acid amides or glycerol fatty acid partial esters is also described as well as the sample preparation for coolants lubricants. (orig.) [Deutsch] Lipophile Tenside werden haeufig zur Herstellung von Oel-in-Wasser-Emulsionen verwandt, wie sie beispielsweise in Kuehlschmiermitteln eingesetzt werden. Typische Vertreter dieser Tenside sind niedrig ethoxylierte Fettalkohole und Alkylphenole. Wegen ihres geringen Ethoxylierungsgrades koennen sie mit den konventionellen Methoden nicht analytisch bestimmt werden. Die hier beschriebene Analysenmethode beruht auf der Derivatisierung der Ethoxylate zu entsprechenden anionischen Tensiden (Ethersulfate). Diese koennen ohne weiteres mit den etablierten Titrationsverfahren bestimmt werden. Die Anwendung dieses neuen Verfahrens auf die Bestimmung anderer nichtionischer Tenside - Sorbitanester, (ethoxylierte) Fettsaeureamide und Partialglyceride - wird ebenso beschrieben wie die Probenvorbereitung fuer die Analyse von Kuehlschmiermitteln. (orig.)

  6. Mitoxantrone-Surfactant Interactions: A Physicochemical Overview

    Directory of Open Access Journals (Sweden)

    Mirela Enache

    2016-10-01

    Full Text Available Mitoxantrone is a synthetic anticancer drug used clinically in the treatment of different types of cancer. It was developed as a doxorubicin analogue in a program to find drugs with improved antitumor activity and decreased cardiotoxicity compared with the anthracyclines. As the cell membrane is the first barrier encountered by anticancer drugs before reaching the DNA sites inside the cells and as surfactant micelles are known as simple model systems for biological membranes, the drugs-surfactant interaction has been the subject of great research interest. Further, quantitative understanding of the interactions of drugs with biomimicking structures like surfactant micelles may provide helpful information for the control of physicochemical properties and bioactivities of encapsulated drugs in order to design better delivery systems with possible biomedical applications. The present review describes the physicochemical aspects of the interactions between the anticancer drug mitoxantrone and different surfactants. Mitoxantrone-micelle binding constants, partitions coefficient of the drug between aqueous and micellar phases and the corresponding Gibbs free energy for the above processes, and the probable location of drug molecules in the micelles are discussed.

  7. 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...

  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. 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)

  10. Minimally Invasive Surfactant Therapy and Noninvasive Respiratory Support.

    Science.gov (United States)

    Kribs, Angela

    2016-12-01

    Respiratory distress syndrome (RDS) caused by surfactant deficiency is major cause for neonatal mortality and short- and long-term morbidity of preterm infants. Continuous positive airway pressure and other modes of noninvasive respiratory support and intubation and positive pressure ventilation with surfactant therapy are efficient therapies for RDS. Because continuous positive airway pressure can fail in severe surfactant deficiency, and because traditional surfactant therapy requires intubation and positive pressure ventilation, this entails a risk of lung injury. Several strategies to combine noninvasive respiratory therapy with minimally invasive surfactant therapy have been described. Available data suggest that those strategies may improve outcome of premature infants with RDS.

  11. 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.

  12. Dimeric Surfactants: Promising Ingredients of Cosmetics and Toiletries

    Directory of Open Access Journals (Sweden)

    Naveen Kumar

    2013-11-01

    Full Text Available Surfactants are an essential ingredient for cosmetic, toiletries and personal care products for enhancing their performance. Dimeric surfactants demonstrate superiority compared to conventional surfactants in all areas of application. Dimeric surfactants are extremely promising for utilization in various cosmetic formulations viz. shampoo, lotions, creams, conditioners etc. These surfactants possess extremely unique surface properties viz. lower surface tension, unique micellization, low critical micelle concentration (CMC and antimicrobial activity, higher solubilization etc. Dimerics enhance the performances of cosmetics in an extraordinary manner and provide eco-friendly preparations for human epidermis.

  13. Effect of temperature on high shear-induced gelation of charge-stabilized colloids without adding electrolytes.

    Science.gov (United States)

    Wu, Hua; Tsoutsoura, Aikaterini; Lattuada, Marco; Zaccone, Alessio; Morbidelli, Massimo

    2010-02-16

    We demonstrated previously (Wu, H.; Zaccone, A.; Tsoutsoura, A.; Lattuada, M.; Morbidelli, M. Langmuir 2009, 25, 4715) that, for a colloid stabilized by charges from both polymer chain-end groups and adsorbed sulfonate surfactants, when the surfactant surface density reaches a certain critical value, the shear-induced gelation becomes unachievable at room temperature, even at an extremely large Peclet number, Pe = 4.6 x 10(4). This is due to the presence of the short-range, repulsive hydration force generated by the adsorbed surfactant. In this work, we investigate how such hydration force affects the shear-induced gelation at higher temperatures, in the range between 303 and 338 K. It is found that a colloidal system, which does not gel at room temperature in a microchannel at a fixed Pe = 3.7 x 10(4), does gel when temperature increases to a certain value. The critical initial particle volume fraction for the gelation to occur decreases as temperature increases. These results indicate that the effect of the hydration force on the gelation decreases as temperature increases. Moreover, we have observed that at the criticality only part of the primary particles is converted to the gel network and the effective particle volume fraction forming the gel network does not change significantly with temperature. The effective particle volume fraction is also independent of the surfactant surface coverage. Since the effective particle volume fraction corresponds to space filling requirement of a standing gel network, which is mainly related to the clusters structure, this result indicates that at a given shear rate the cluster structure does not change significantly with the surfactant surface coverage. On the other hand, since the cluster morphology is a strong function of the shear rate, we have observed that when the Peclet number is lowered from Pe = 3.7 x 10(4) to 1.7 x 10(4), the effective particle volume fraction reduces from 0.19 to 0.12 at 313 K.

  14. Molecular Dynamics Simulation for the Effect of Chain Length of Spacer and Tail of Cationic Gemini Surfactant on the Complex with Anionic Polyelectrolyte%连接基团与尾链长度对阳离子Gemini表面活性剂与阴离子聚电解质复合物影响的分子动力学模拟

    Institute of Scientific and Technical Information of China (English)

    徐毅; 冯剑; 尚亚卓; 刘洪来

    2007-01-01

    Interaction of anionic polyelectrolyte with cationic gemini surfactant has been investigated by coarse-grained molecular dynamics simulation. Polyelectrolyte facilitates the oppositely charged ionic surfactants to aggregate by suppressing the electrostatic repulsion between ionic head groups leading to the formation of micellar complex. With addition of surfactant, the conformation of polyion chain changes from stretched to random coiled to spherical, and at the same time more free micelles are formed by surfactants in mixtures. Increasing the length of spacer or tail chain in gemini surfactant will weaken its interaction with polyelectrolyte and simultaneously strengthen its tendency to self-assemble. The simulation results are consistent with experimental observations and reveal that the electrostatic interaction plays an important role in the interaction of polyelectrolyte with gemini surfactant.

  15. Use of two-surfactants mixtures to attain specific HLB values for assisted TPH-diesel biodegradation

    Institute of Scientific and Technical Information of China (English)

    Luis G. Torres; Neftalí Rojas; Rosario Iturbe

    2004-01-01

    In a surfactant assisted biodegradation process, the choice of surfactant(s) is of crucial importance. The question is: does the type of surfactant (i.e. chemical family) affect the biodegradation process at fixed hidrophillic-lypofillic balance HLB values? Microcosm assessments were developed using contaminated soil, with around of 5000 mg/kg of hydrocarbons as TPH-diesel. Mixtures of three nonionic surfactants were employed to get a wide range of specific HLB values. Tween20 and Span20 were mixed in the appropriate proportions to get HLB values between 8.6 and 16.7. Tween/Span60 mixtures reached HLB values between 4.7 and 14.9. Finally, Tween/Span80 combinations yielded HLB values between 4.3 and 15. TPH-diesel biodegradation was measured at the beginning, and after 8 weeks, as well as the FCU/grsoil, as a measure of microorganisms′ development during the biodegradation period. A second aim of this work was to assess the use of guar gum as a biodegradation enhancer instead of synthetic products. The conclusions of this work are that surfactant chemical family, and not only the HLB value clearly affects the assisted biodegradation rate. Surfactant's synergism was clearly observed. Regarding the use of guar gum, no biodegradation enhancement was observed for the three assessed concentrations i.e., 2, 20, and 200 mg/kg, respectively. On the contrary, TPH-diesel removal was lower as the gum concentration increased. It is quite possible that guar gum was used as a microbial substrate.

  16. SURFACTANT BASED ENHANCED OIL RECOVERY AND FOAM MOBILITY CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    George J. Hirasaki; Clarence A. Miller; Gary A. Pope; Richard E. Jackson

    2004-02-01

    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. Also, the addition of an alkali such as sodium carbonate makes possible in situ generation of surfactant and significant reduction of surfactant adsorption. In addition to reduction of interfacial tension to ultra-low values, surfactants and alkali can be designed to alter wettability to enhance oil recovery. An alkaline surfactant process is designed to enhance spontaneous imbibition in fractured, oil-wet, carbonate formations. It is able to recover oil from dolomite core samples from which there was no oil recovery when placed in formation brine.

  17. Enhance transdermal delivery of flurbiprofen via microemulsions: Effects of different types of surfactants and cosurfactants

    Science.gov (United States)

    Idrees, MA.; Rahman, NU.; Ahmad, S.; Ali, MY.; Ahmad, I.

    2011-01-01

    Background and the purpose of the study Microemulsions are thermodynamically stable, clear dispersions of water, oil, surfactant, and cosurfactant. This study was aimed to develop flurbiprofen microemulsion for enhanced transdermal delivery and investigate the effects of different surfactants and cosurfactants on its delivery and phase behavior. Method Various surfactant-cosurfactant mixtures in ratio of 2:1 (Smix) along with oleic acid (oil) were selected and phase diagrams were constructed. Six microemulsions each containing 5% drug, 5% oil, 56% Smix and 34% water, were prepared and compared for their permeation and phase behaviors to determine the effects of the type of Smix. Results In vitro transdermal permeation through rabbit skin of all microemulsions was high than saturated aqueous drug solution. Tween 20 and ethanol as Smix produced the highest flux amongst all the Smix, and were used to prepare formulations with different values of oil and Smix. While the type of surfactant did not affect the droplet size, propylene glycol as cosurfactant produced the largest droplets and highest viscosity. Decrease in oil or Smix concentration resulted in decrease of the droplet size and increase in permeation flux while decrease in viscosity also increased the permeation flux of microemulsions. Finally the selected microemulsion formulation comprising 5% flurbiprofen, 5% oleic acid, 46% Tween 20:ethanol (2:1) and 44% water, showed the highest transdermal flux and caused no skin irritation. Conclusion Type of surfactant and cosurfactant affect both the phase behavior and transdermal drug delivery of microemulsion; and results of this study showed that they are promising vehicles for improved transdermal delivery and sustained action of flurbiprofen. PMID:23008689

  18. Enhance Transdermal Delivery of Flurbiprofen Via Microemulsions: Effects of Different Types of Surfactants and Cosurfactants

    Directory of Open Access Journals (Sweden)

    S. Ahmad

    2011-12-01

    Full Text Available Background and the purpose of the study: Microemulsions are thermodynamically stable, clear dispersions of water, oil, surfactant, and cosurfactant. This study was aimed to develop flurbiprofen microemulsion for enhanced transdermal delivery and investigate the effects of different surfactants and cosurfactants on its delivery and phase behavior.Method: Various surfactant-cosurfactant mixtures in ratio of 2:1 (Smix along with oleic acid (oil were selected and phase diagrams were constructed. Six microemulsions each containing 5% drug, 5% oil, 56% Smix and 34% water, were prepared and compared for their permeation and phase behaviors to determine the effects of the type of Smix.Results: In vitro transdermal permeation through rabbit skin of all microemulsions was high than saturated aqueous drug solution. Tween 20 and ethanol as Smix produced the highest flux amongst all the Smix, and were used to prepare formulations with different values of oil and Smix. While the type of surfactant did not affect the droplet size, propylene glycol as cosurfactant produced the largest droplets and highest viscosity. Decrease in oil or Smix concentration resulted in decrease of the droplet size and increase in permeation flux while decrease in viscosity also increased the permeation flux of microemulsions. Finally the selected microemulsion formulation comprising 5% flurbiprofen, 5% oleic acid, 46% Tween 20:ethanol (2:1 and 44% water, showed the highest transdermal flux and caused no skin irritation.Conclusion: Type of surfactant and cosurfactant affect both the phase behavior and transdermal drug delivery of microemulsion; and results of this study showed that they are promising vehicles for improved transdermal delivery and sustained action of flurbiprofen.

  19. CHARACTERIZATION OF PHASE AND EMULSION BEHAVIOR, SURFACTANT RETENTION, AND OIL RECOVERY FOR NOVEL ALCOHOL ETHOXYCARBOXYLATE SURFACTANTS

    Energy Technology Data Exchange (ETDEWEB)

    Lebone T. Moeti; Ramanathan Sampath

    2001-09-28

    This final technical report describes work performed under DOE Grant No. DE-FG26-97FT97278 during the period October 01, 1997 to August 31, 2001 which covers the total performance period of the project. During this period, detailed information on optimal salinity, temperature, emulsion morphologies, effectiveness for surfactant retention and oil recovery was obtained for an Alcohol Ethoxycarboxylate (AEC) surfactant to evaluate its performance in flooding processes. Tests were conducted on several AEC surfactants and NEODOX (23-4) was identified as the most suitable hybrid surfactant that yielded the best proportion in volume for top, middle, and bottom phases when mixed with oil and water. Following the selection of this surfactant, temperature and salinity scans were performed to identify the optimal salinity and temperature, and the temperature and salinity intervals in which all three phases coexisted. NEODOX 23-4 formed three phases between 4 and 52.5 C. It formed an aqueous rich microemulsion phase at high temperatures and an oleic rich microemulsion phase at low temperatures--a characteristic of the ionic part of the surfactant. The morphology measurement system was set-up successfully at CAU. The best oil/water/surfactant system defined by the above phase work was then studied for emulsion morphologies. Electrical conductivities were measured for middle and bottom phases of the NEODOX 23-4/dodecane/10mM water system and by mixing measured volumes of the middle phase into a fixed volume of the bottom phase and vice versa at room temperature. Electrical conductivity of the mixture decreased as the fraction of volume of the middle phase was increased and vice versa. Also inversion phenomena was observed. These experiments were then repeated for bottom/middle (B/M) and middle/bottom (M/B) conjugate pair phases at 10, 15, 25, 30, 35, 40, and 45 C. Electrical conductivity measurements were then compared with the predictions of the conductivity model developed in

  20. Dielectric sample with two-layer charge distribution for space charge calibration purposes

    DEFF Research Database (Denmark)

    Holbøll, Joachim; Henriksen, Mogens; Rasmussen, C.

    2002-01-01

    In the present paper is described a dielectric test sample with two very narrow concentrations of bulk charges, achieved by two internal electrodes not affecting the acoustical properties of the sample, a fact important for optimal application of most space charge measuring systems. Space charge...

  1. Cytotoxicity Effects of Different Surfactant Molecules Conjugated to Carbon Nanotubes on Human Astrocytoma Cells

    Science.gov (United States)

    Dong, Lifeng; Witkowski, Colette M.; Craig, Michael M.; Greenwade, Molly M.; Joseph, Katherine L.

    2009-12-01

    Phase contrast and epifluorescence microscopy were utilized to monitor morphological changes in human astrocytoma cells during a time-course exposure to single-walled carbon nanotube (SWCNT) conjugates with different surfactants and to investigate sub-cellular distribution of the nanotube conjugates, respectively. Experimental results demonstrate that cytotoxicity of the nanotube/surfactant conjugates is related to the toxicity of surfactant molecules attached on the nanotube surfaces. Both sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) are toxic to cells. Exposure to CNT/SDS conjugates (0.5 mg/mL) for less than 5 min caused changes in cell morphology resulting in a distinctly spherical shape compared to untreated cells. In contrast, sodium cholate (SC) and CNT/SC did not affect cell morphology, proliferation, or growth. These data indicate that SC is an environmentally friendly surfactant for the purification and dispersion of SWCNTs. Epifluorescence microscopy analysis of CNT/DNA conjugates revealed distribution in the cytoplasm of cells and did not show adverse effects on cell morphology, proliferation, or viability during a 72-h incubation. These observations suggest that the SWCNTs could be used as non-viral vectors for diagnostic and therapeutic molecules across the blood-brain barrier to the brain and the central nervous system.

  2. "The effects of polysorbate surfactants on the structure of mucus Glycoproteins "

    Directory of Open Access Journals (Sweden)

    Sajadi Tabassi A

    2001-07-01

    Full Text Available A dynamic oscillatory technique was used to assess the effect of polysorbate non-ionic surfactants on mucus rheology. Adherent mucus gel was scraped from the surface mucosa of pig stomachs and purified by gel exclusion chromatography followed by ultrafiltration and gelation. Rheological measurements of this gel were carried out on a Carri-Med Controlled Stress Rheometer. Appropriate volumes of surfactant solution were added to weighed samples of mucus gel so that a final concentration of 20 mM surfactant was achieved in a gel containing 8% w/w solids content. Polysorbate 20 (PS20, polysorbate 40 (PS40, polysorbate 60 (PS60 and polysorbate 80 (PS80 all decreased both storage (elastic modulus G’ and loss (viscous modulus G’’ significantly at 10 Hz (PPS20>PS60>PS40. The mechanisms by which surfactants disturb the mucus structure are not fully understood, nonetheless, they could possibly affect the mucus gel properties by causing depletion of the glycoprotein constituents such as non-mucin proteins and mucin associated lipids. This might lead to the conclusion that polysorbates, by reducing the viscoelasticity of mucus gel could alleviate its barrier properties and facilitate the diffusion of concomitantly administered drugs via mucus gel.

  3. Manipulating perfume delivery to the interface using polymer-surfactant interactions.

    Science.gov (United States)

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

    2016-03-15

    Enhanced delivery of perfumes to interfaces is an important element of their effectiveness in a range of home and personal care products. The role of polyelectrolyte-surfactant mixtures to promote perfume adsorption at interfaces is explored here. Neutron reflectivity, NR, was used to quantify the adsorption of the model perfumes phenylethanol, PE, and linalool, LL, at the air-water interface in the presence of the anionic surfactant sodium dodecylsulfate, SDS, and the cationic polyelectrolytes, poly(dimethyldiallyl ammonium chloride), polydmdaac, and poly(ethyleneimine), PEI. The strong SDS-polydmdaac interaction dominates the surface adsorption in SDS-polymer-perfume (PE, LL) mixtures, such that the PE and LL adsorption is greatly suppressed. For PEI-SDS-perfume mixtures the PEI-LL interaction competes with the SDS-PEI interaction at all pH at the surface and significant LL adsorption occurs, whereas for PE the PEI-SDS interaction dominates and the PE adsorption is greatly reduced. The use of the strong surface polyelectrolyte-ionic surfactant interaction to manipulate perfume adsorption at the air-water interface has been demonstrated. In particular the results show how the competition between polyelectrolyte, surfactant and perfume interactions at the surface and in solution affect the partitioning of perfumes to the surface.

  4. Surfactant-assisted sol–gel synthesis of forsterite nanoparticles as a novel drug delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Hassanzadeh-Tabrizi, S.A., E-mail: tabrizi1980@gmail.com [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Bigham, Ashkan [Advanced Materials Research Center, Materials Engineering Department, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Rafienia, Mohammad [Biosensor Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of)

    2016-01-01

    In the present study, forsterite nanoparticles were synthesized via surfactant-assisted sol–gel method using cetyltrimethyl ammonium bromide (CTAB) as a surfactant. The effects of CTAB contents and heat treatment on the textural properties and drug release from nanoparticles were investigated. The synthesized powders were studied by X-ray diffraction, Fourier transform infrared spectra, Brunauer–Emmett–Teller surface area analysis and transmission electron microscope images. Mg{sub 2}SiO{sub 4} materials demonstrated mesoporous characteristics and large specific surface area ranging from 159 to 30 m{sup 2}/g. The TEM results showed that forsterite nanorods had diameters about 4 nm and lengths ranging from 10 to 60 nm. It was found that the samples with 6 g CTAB show slower drug release rate than the other specimens, which is due to smaller pore size. This study revealed that the drug delivery of forsterite can be tailored by changing the amount of surfactant. - Highlights: • Forsterite nanoparticles were synthesized via surfactant-assisted sol–gel method. • Nanoparticles were loaded with ibuprofen as a novel drug delivery system. • Synthesized nanoparticles had a rod-like morphology. • CTAB concentration strongly affected the textural properties and drug release of the nanoparticles.

  5. Sorption of a nonionic surfactant Tween 80 by minerals and soils.

    Science.gov (United States)

    Kang, Soyoung; Jeong, Hoon Young

    2015-03-02

    Batch experiments were conducted to evaluate Tween 80 sorption by oxides, aluminosilicates, and soils. For oxides, the sorption by silica and alumina follow linear isotherms, and that by hematite follows a Langmuir isotherm. Considering isotherm type and surface coverage, Tween 80 may partition into the silica/alumina-water interface, whereas it may bind to hematite surface sites. Among aluminosilicates, montmorillonite shows the greatest sorption due to the absorption of Tween 80 into interlayers. For other aluminosilicates, it sorbs to surfaces, with the sorption increasing as plagioclaseTween 80 sorption. The greater sorption by untreated soils than H2O2-treated soils indicates that soil organic matter is a vital sorbent. The sorption hysteresis, contributed to by clay minerals and soil organic matter, is characterized by the greater sorption during the desorption than the sorption stages. This suggests the potential difficulty in removing surfactants from soils. Also, sorption of surfactants can adversely affect surfactant-enhanced remediation by decreasing the aquifer permeability and the availability of surfactants for micellar solubilization.

  6. Accumulation of yellow Monascus pigments by extractive fermentation in nonionic surfactant micelle aqueous solution.

    Science.gov (United States)

    Xiong, Xu; Zhang, Xuehong; Wu, Zhenqiang; Wang, Zhilong

    2015-02-01

    Monascus species can produce various secondary metabolites of polyketide structure. In the current study, it is found that an interesting phenomenon, i.e., submerged culture of Monascus species in an aqueous solution majorly accumulated intracellular orange Monascus pigments exhibiting one peak at 470 nm with absorbance of 32 OD while extractive fermentation in a nonionic surfactant micelle aqueous solution produced extracellular and intracellular yellow Monascus pigments exhibiting one peak at 410 nm with absorbance 30 OD and 12 OD, respectively. The spectrum profiles of both intracellular and extracellular Monascus pigments were affected by surfactant loading, extractive fermentation time, and surfactant adding time. Meanwhile, the instability of orange Monascus pigments in the extracellular nonionic surfactant micelle aqueous solution was also confirmed experimentally. The mechanism behind this phenomenon is attributed to the export of intracellular yellow Monascus pigments into its broth by extractive fermentation. The transferring of intracellular yellow Monascus pigments into its broth blocks yellow Monascus pigments from further enzymatic conversion or eliminates the feedback inhibition of yellow Monascus pigments based on the biosynthetic pathway of Monascus pigments.

  7. Cytotoxicity Effects of Different Surfactant Molecules Conjugated to Carbon Nanotubes on Human Astrocytoma Cells

    Directory of Open Access Journals (Sweden)

    Witkowski Colette

    2009-01-01

    Full Text Available Abstract Phase contrast and epifluorescence microscopy were utilized to monitor morphological changes in human astrocytoma cells during a time-course exposure to single-walled carbon nanotube (SWCNT conjugates with different surfactants and to investigate sub-cellular distribution of the nanotube conjugates, respectively. Experimental results demonstrate that cytotoxicity of the nanotube/surfactant conjugates is related to the toxicity of surfactant molecules attached on the nanotube surfaces. Both sodium dodecyl sulfate (SDS and sodium dodecylbenzene sulfonate (SDBS are toxic to cells. Exposure to CNT/SDS conjugates (0.5 mg/mL for less than 5 min caused changes in cell morphology resulting in a distinctly spherical shape compared to untreated cells. In contrast, sodium cholate (SC and CNT/SC did not affect cell morphology, proliferation, or growth. These data indicate that SC is an environmentally friendly surfactant for the purification and dispersion of SWCNTs. Epifluorescence microscopy analysis of CNT/DNA conjugates revealed distribution in the cytoplasm of cells and did not show adverse effects on cell morphology, proliferation, or viability during a 72-h incubation. These observations suggest that the SWCNTs could be used as non-viral vectors for diagnostic and therapeutic molecules across the blood–brain barrier to the brain and the central nervous system.

  8. Activity, stability and kinetic parameters for -chymotrypsin catalysed reactions in AOT/isooctane reverse micelles with nonionic and zwitterionic mixed surfactants

    Indian Academy of Sciences (India)

    Santosh Kumar Verma; Kallol K Ghosh

    2013-07-01

    Reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulphosuccinate (AOT) in nonpolar organic solvents are widely known to have very high solubilization power for water. The method is applied to the hydrolysis of -nitrophenyl acetate (PNPA) catalysed by -chymotrypsin (-CT) in AOT/isooctane/buffer RMs. The increase in -CT activity and stability was an optimum at wo ([H2O]/[AOT]) = 10, z [Isooctane]/[AOT]) = 5. Three typical surfactants were selected based on their head group charges: a non-ionic surfactant Triton-X 100 and two zwitterionic sulphobetaine surfactants of the type CH2+1N+Me2 (CH2)3 SO$^{−}_{3}$ (n = 10; SB3-10, n = 16; SB3-16). The kinetic parameters (such as cat and M) of the -CT at 27°C were determined and compared in the absence and presence of three surfactants. The effect of chain length of zwitterionic surfactant (SB3-10 and SB3-16) on the enzymatic efficacy of -CT as a function of mixed surfactant addition has been investigated in AOT/isooctane RMs at pH 7.75.

  9. CHARGE Association

    Directory of Open Access Journals (Sweden)

    Semanti Chakraborty

    2012-01-01

    Full Text Available We present here a case of 17-year-old boy from Kolkata presenting with obesity, bilateral gynecomastia, mental retardation, and hypogonadotrophic hypogonadism. The patient weighed 70 kg and was of 153 cm height. Facial asymmetry (unilateral facial palsy, gynecomastia, decreased pubic and axillary hair, small penis, decreased right testicular volume, non-palpable left testis, and right-sided congenital inguinal hernia was present. The patient also had disc coloboma, convergent squint, microcornea, microphthalmia, pseudohypertelorism, low set ears, short neck, and choanalatresia. He had h/o VSD repaired with patch. Laboratory examination revealed haemoglobin 9.9 mg/dl, urea 24 mg/dl, creatinine 0.68 mg/dl. IGF1 77.80 ng/ml (decreased for age, GH <0.05 ng/ml, testosterone 0.25 ng/ml, FSH-0.95 ΅IU/ml, LH 0.60 ΅IU/ml. ACTH, 8:00 A.M cortisol, FT3, FT4, TSH, estradiol, DHEA-S, lipid profile, and LFT was within normal limits. Prolactin was elevated at 38.50 ng/ml. The patient′s karyotype was 46XY. Echocardiography revealed ventricularseptal defect closed with patch, grade 1 aortic regurgitation, and ejection fraction 67%. Ultrasound testis showed small right testis within scrotal sac and undescended left testis within left inguinal canal. CT scan paranasal sinuses revealed choanalatresia and deviation of nasal septum to the right. Sonomammography revealed bilateral proliferation of fibroglandular elements predominantly in subareoalar region of breasts. MRI of brain and pituitary region revealed markedly atrophic pituitary gland parenchyma with preserved infundibulum and hypothalamus and widened suprasellar cistern. The CHARGE association is an increasingly recognized non-random pattern of congenital anomalies comprising of coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear abnormalities, and/or deafness. [1] These anomalies have a higher probability of occurring together. In this report, we have

  10. Alcohol--Induced Polyelectrolyte-Surfactant Complex Coacervate Systems: Characterization and Applications in Enzyme and Protein Extraction

    Science.gov (United States)

    Nejati Moshtaghin, Mahboubeh

    The focus of this thesis is to achieve a better understanding of the newly discovered surfactant-polyelectrolyte complex coacervate (SPCC) systems induced by fluoroalcohol/acid as well as short chain aliphatic alcohol; and to elucidate their applications in extraction and enrichment of proteins and enzyme. We have discovered that fluoroalcohols and --acids induce complex coacervation and phase separation in the aqueous mixtures of oppositely charged anionic polyelectrolytes; specifically, sodium salts of polyacrylic acid and polymethacrylic acid and cationic surfactant (cetyltrimethylammonium bromide, CTAB) over a broad range of concentrations of mole fractions of the oppositely charged amphiphiles. Accordingly, these new classes of coacervators will significantly broaden the scope and facilitate engineering of new coacervate phases. Toward these goals, we have inspected the formation of surfactant-polyelectrolyte complex coacervates in the presence of fluoroalcohols namely hexafluoroisopropanol (HFIP) and Trifluoroethanol (TFE). Furthermore, the extent of coacervation as a function of concentrations the system components, and charge ratios of the oppositely charged amphiphiles has been investigated. Polyelectrolytes are considered to be milder reagents, as compared to surfactants, regarding proteins denaturation. This highlights the importance of a detailed investigation of the efficiency of our coacervate systems for extraction and preconcentration of proteins and enzymes, especially, when the biological activity of the extracted proteins needs to be maintained based on the objectives mentioned above, the results of the investigations have been organized in four chapters. In Chapter II, the phase behavior of the FA-SPCC will be investigated. The objective is to examine the phase behavior and phase properties with respect to the extent of coacervation in different solution conditions. In particular, the effects of different solution variables such as concentration

  11. 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

  12. Ultrasmall semiconductor particles sandwiched between surfactant headgroups in Langmuir-Blodgett films

    Energy Technology Data Exchange (ETDEWEB)

    Shuqian Xu; Xiao Kang Zhao, Fendler, J.H. (Syracuse Univ., NY (United States))

    1990-04-01

    Successful sandwiching of size-quantized hexametaphosphate-stabilized CdS particles between monomolecular layers of dioctadecyldimethylammonium chloride (DODAC) surfactants, deposited on solid substrates, was accomplished. Electrostatic forces are responsible for attracting the negatively charged CdS particles onto the cationic headgroups of the substrate-supported DODAC monolayer, immersed in the aqueous subphase. These forces also ensure that, during withdrawal of the DODAC-monolayer-coated substrate, the CdS particles remain in place, attract a second monolayer of DODAC, and thereby form a DODAC-CdS particle-DODAC sandwich.

  13. Uniform biodegradable hydrogel microspheres fabricated by a surfactant-free electric-field-assisted method.

    Science.gov (United States)

    Choy, Young Bin; Choi, Hyungsoo; Kim, Kyekyoon Kevin

    2007-04-10

    Uniform biodegradable hydrogel microspheres (HMS) with precisely controlled size have been fabricated using an electric-field-assisted precision particle fabrication technique. Particle agglomeration was prevented by charging the hydrogel drops and allowing Coulomb repulsion to separate them. As a result, surfactant-free and non-toxic particle fabrication was possible and the resulting microspheres were most suitable for biomedical and food-related applications. Due to the size uniformity, the present HMS may serve as a convenient yet most accurate vehicle for controlled delivery of therapeutic agents and other active ingredients.

  14. Use of polymers and a surfactant in the treatment of Kraft process wastewater

    OpenAIRE

    Seyffert, Hans J.

    1988-01-01

    This study-investigated the use of cationic polymers, and a surfactant, EHDABr, in the color removal treatment of Kraft pulp and paper wastewater. Four polymers were evaluated for their color removal performance by jar test procedures. The polymers removed between 77 and 87% of the wastewater color. The affect of pH upon polymer performance varied with the polymer tested. Powdered activated carbon addition improved the performance of the polymers. The color removal abili...

  15. Modeling of surfactant transport and adsorption in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Chung, F.T.H.

    1991-04-01

    When surfactant solution is flowing in a reservoir formation, surfactants will be diluted by flow dispersion, retained in dead-end pores, adsorbed on rock surfaces, or precipitated due to ion exchange. The loss of surfactant will be detrimental to the performance of gas foam. Information of surfactant concentration profiles in reservoir formations is essential for gas foaming technique development. The major objective of this research is to investigate with mathematical models the transport and dynamic adsorption of surfactants in porous media. The mathematical models have taken into account the convection, dispersion, capacitance, and adsorption effects on concentrations of surfactants. Numerical methods and computer programs have been developed which can be used to match experimental results and to determine the characterization parameters in the models. The models can be included in foam simulation programs to calculate surfactant concentration profiles in porous media. A flow experimental method was developed to measure the effluent surfactant concentration, which will be used to determine the model parameters. Commercial foaming agent Alipal CD-128 was used in this study. Equilibrium adsorption and surfactant precipitation have been tested. Tracer solutions with a nonadsorbing solute such as dextrose and sucrose were used to determine the dispersion parameters for the experimental sandpack; thus, the adsorption of the surfactant in the test sand can be identified with an adequate model. 49 refs., 21 figs.

  16. Pulmonary surfactant adsorption is increased by hyaluronan or polyethylene glycol.

    Science.gov (United States)

    Taeusch, H William; Dybbro, Eric; Lu, Karen W

    2008-04-01

    In acute lung injuries, inactivating agents may interfere with transfer (adsorption) of pulmonary surfactants to the interface between air and the aqueous layer that coats the interior of alveoli. Some ionic and nonionic polymers reduce surfactant inactivation in vitro and in vivo. In this study, we tested directly whether an ionic polymer, hyaluronan, or a nonionic polymer, polyethylene glycol, enhanced adsorption of a surfactant used clinically. We used three different methods of measuring adsorption in vitro: a modified pulsating bubble surfactometer; a King/Clements device; and a spreading trough. In addition we measured the effects of both polymers on surfactant turbidity, using this assay as a nonspecific index of aggregation. We found that both hyaluronan and polyethylene glycol significantly increased the rate and degree of surfactant material adsorbed to the surface in all three assays. Hyaluronan was effective in lower concentrations (20-fold) than polyethylene glycol and, unlike polyethylene glycol, hyaluronan did not increase apparent aggregation of surfactant. Surfactant adsorption in the presence of serum was also enhanced by both polymers regardless of whether hyaluronan or polyethylene glycol was included with serum in the subphase or added to the surfactant applied to the surface. Therefore, endogenous polymers in the alveolar subphase, or exogenous polymers added to surfactant used as therapy, may both be important for reducing inactivation of surfactant that occurs with various lung injuries.

  17. 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

  18. A high-resolution study of surfactant partitioning and kinetic limitations for two-component internally mixed aerosols

    Science.gov (United States)

    Suda, S. R.; Petters, M. D.

    2013-12-01

    Atmospheric aerosols serve as cloud condensation nuclei (CCN), altering cloud properties and ultimately affecting climate through their effect on the radiative balance. Aerosol CCN activity depends in part on aerosol composition and surfactant compounds are of particular interest because surfactants are enriched at the water/air interface, resulting in a radial concentration gradient within the aqueous droplet. Accurate treatment of the surfactant concentration gradient complicates the otherwise straightforward predictions of CCN activity for aerosols of known composition. To accurately evaluate predictions made by theory, laboratory studies investigating the relationship between critical supersaturation and dry diameter of particles that include surfactants require significant reduction in measurement uncertainty for both water-uptake and CCN measurements. Furthermore, uncertainties remain regarding kinetic limitations to surfactant partitioning that could result in deviation from predictions based on equilibrium thermodynamics. This study attempts to address some of these issues through high-resolution analysis of CCN activity of two-component mixed surfactant/non-surfactant aerosols at different internal mixing ratios performed with and without a water-uptake time delay to ascertain whether or not the observed effects are kinetically limited. We present new data for the aerosols consisting of 1) the ionic surfactant sodium dodecyl sulfate (SDS) with ammonium sulfate, 2) SDS with sodium chloride and 3) the strong non-ionic fluorosurfactant Zonyl with an organic proxy glucose. As a point of reference we also evaluated the mixture of ammonium sulfate with glucose. Aerosol activation diameters were determined using CCN analysis in conjunction with scanning mobility size classification and high sheath-to-aerosol flow ratios. This resulted in CCN-derived kappa values that could be determined within +/-5% relative error. To test whether dynamic surfactant partitioning

  19. 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.

  20. Emerging dynamics in surfactant-based liquid mixtures: Octanoic acid/bis(2-ethylhexyl) amine systems

    Science.gov (United States)

    Calandra, Pietro; Mandanici, Andrea; Turco Liveri, Vincenzo; Pochylski, Mikolaj; Aliotta, Francesco

    2012-02-01

    This work focuses on the dynamic phenomena emerging in self-assembled transient intermolecular networks formed when two different surfactants are mixed. In particular, the relaxation processes in liquid mixtures composed by bis(2-ethylhexyl)amine (BEEA) and octanoic acid (OA) in the whole composition range has been investigated by dielectric spectroscopy and Brillouin spectroscopy. A thorough analysis of all the experimental data consistently suggests that, mainly driven by acid-base interactions arising when the two surfactants are mixed, supra-molecular aggregates formation causes the slowing down of molecular dynamics. This, in turn, reflects to longer-range relaxations. These changes have been found to be composition-dependent, involving strong departures of the mixture physico-chemical properties from an ideal behaviour, and reflecting the structural and dynamical features of local structures. In particular, the peculiar dynamic processes occurring in these local inter-molecular structures, have been found to be the factors responsible for the observed and quite surprising increase of direct-current conductivity which occurs when two different (and pretty non-conductive) surfactants are mixed. The discovery can be used not only to design novel materials for application purposes but also to shed more light on the basic principles regulating charge migration in structured liquid systems.

  1. Multi-scale simulation studies on interaction between anionic surfactants and cations

    Directory of Open Access Journals (Sweden)

    Siwei Meng

    2014-12-01

    Full Text Available In this paper, a dissipative particle dynamics (DPD simulation method was used to investigate the impact of cations on the rheological properties of dodecyl sulfonate surfactant solutions. In order to obtain reasonable interaction between head groups of the surfactant, the geometric structure and interaction between dodecyl sulfonate and cations are optimized using density function theory (DFT at the B3LYP/6-31G level. The DFT calculated results indicate that α-methylene nearest the head group can be classified as a part of the polar head. After binding, the charge on polar head decreases, thus greatly reduces the repulsion between the head groups. It is found that the presence of counterions is one of induction factors on the formation of wormlike micelles, thus greatly enhances the viscosity of surfactant solution. With the increasing in shear strengthen, the wormlike micelles are gradually oriented in the x direction and then broken up into small spherical micelles. This process is also shown by the decrease of viscosity, which decreases quickly at the low shear rates, then keeps almost a constant at the moderate shear rates and at last decreases again at the shear rates larger than a critical value. Compared with monovalent cations, divalent cations have a stronger effect on the rheological properties of dodecyl sulfonate solutions.

  2. Influence of charged microenvironment on redox potential and diffusion coefficient of [Fe4S4(SPh)4](NBu4)2 in DMF and inside CTAB film on electrode surface

    Indian Academy of Sciences (India)

    Raben Ch Roy; Diganta Kumar Das

    2005-11-01

    Redox potential of [Fe4S4(SPh)4]2-/3-, a model of the active centre of ferredoxin, in DMF solution shows a 90-mV positive shift, when the charged microenvironment provided by the surfactant is changed from negative to positive. Inside the positive surfactant film on GC electrode there is a 235-mV positive shift in redox potential compared to that in neutral DMF solution. Diffusion coefficient of the reduced cluster onto the electrode surface is also found to be 102 times greater in the presence of negative surfactant compared to that in positive surfactant.

  3. Weak non-linear surface charging effects in electrolytic films

    OpenAIRE

    Dean, D. S.; Horgan, R. R.

    2002-01-01

    A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full non-linear surface terms which are then treated at a one-loop level by calculating the mean-field Poisson-Boltzmann solution and then the fluctuations about this solution. We carefully analyze the reno...

  4. Preparation and evaluation of sulphonamide nonionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M. H. M.

    2010-07-01

    Alkyl (octyl, decyl and dodecyl; C{sub 8}, C{sub 1}0 and C{sub 1}2) benzene sulphonyl chloride was used in the preparation of a novel series of nonionic surfactants (IV-VI)a-c, (VII-IX) a-c and (X-XII)a-c. The preparations were completed by reacting each alkyl (C{sub 8}, C{sub 1}0 and C{sub 1}2) benzene sulphonyl chloride with ethanolamine to give (I-III) respectively. The resulting products were reacted separately with ethylene oxide in the presence of different (base KOH, Lewis acid SnCl4 and k10 clay) catalysts to produce different moles of nonionic surfactants (5, 7 and 9) in sequence corresponding to (IV-VI)a-c, (VII-IX) a-c and (X-XII)a-c respectively. The chemical structures of prepared nonionic surfactants were elucidated by IR and 1HNMR spectra. The surface activity, biodegradability and biological activities of the prepared compounds were investigated. The obtained data show that these compounds have good surface and biological activities as well as reasonable biodegradability properties. (Author) 30 refs.

  5. Therapeutic surfactant-stripped frozen micelles

    Science.gov (United States)

    Zhang, Yumiao; Song, Wentao; Geng, Jumin; Chitgupi, Upendra; Unsal, Hande; Federizon, Jasmin; Rzayev, Javid; Sukumaran, Dinesh K.; Alexandridis, Paschalis; Lovell, Jonathan F.

    2016-05-01

    Injectable hydrophobic drugs are typically dissolved in surfactants and non-aqueous solvents which can induce negative side-effects. Alternatives like `top-down' fine milling of excipient-free injectable drug suspensions are not yet clinically viable and `bottom-up' self-assembled delivery systems usually substitute one solubilizing excipient for another, bringing new issues to consider. Here, we show that Pluronic (Poloxamer) block copolymers are amenable to low-temperature processing to strip away all free and loosely bound surfactant, leaving behind concentrated, kinetically frozen drug micelles containing minimal solubilizing excipient. This approach was validated for phylloquinone, cyclosporine, testosterone undecanoate, cabazitaxel and seven other bioactive molecules, achieving sizes between 45 and 160 nm and drug to solubilizer molar ratios 2-3 orders of magnitude higher than current formulations. Hypertonic saline or co-loaded cargo was found to prevent aggregation in some cases. Use of surfactant-stripped micelles avoided potential risks associated with other injectable formulations. Mechanistic insights are elucidated and therapeutic dose responses are demonstrated.

  6. A novel approach to enhancement of surface properties of CdO films by using surfactant: dextrin

    Science.gov (United States)

    Sahin, Bünyamin; Bayansal, Fatih; Yüksel, Mustafa

    2015-12-01

    We studied the effect of an organic surfactant, dextrin, concentration on structural, morphological and optical properties of nanostructured CdO films deposited on glass substrates by using an easy and low-cost SILAR method. Microstructures of the nanostructured CdO films were optimized by adjusting dextrin concentration. XRD, SEM and UV-Vis Spectroscopy were used to study phase structure, surface morphology and optical properties of CdO films. Furthermore, effects of dextrin concentration on the surface roughness characteristics of CdO samples were reported. The results showed that the presence of organic surfactant highly affected the physical properties of CdO nanomaterials.

  7. MINERAL-SURFACTANT INTERACTIONS FOR MINIMUM REAGENTS PRECIPITATION AND ADSORPTION FOR IMPROVED OIL RECOVERY

    Energy Technology Data Exchange (ETDEWEB)

    P. Somasundaran

    2006-04-30

    During this reporting period, further fundamental studies were conducted to understand the mechanism of the interactions between surfactants and minerals with the aim of minimizing chemical loss by adsorption. The effects of pH and mixing ratio on the chemical loss by adsorption were investigated. Some preliminary modeling work has been done towards the aim of developing a guide book to design optimal polymer/surfactant formula based on the understanding of adsorption and orientation of surfactants and their aggregates at solid/liquid interfaces. The study of adsorption of mixed system of n-dodecyl-{beta}-D-maltoside (DM) and dodecyl sulfonate (C{sub 12}SO{sub 3}Na) was continued during this period. Based on the adsorption results, the effects of pH and mixing ratio on reagent loss were quantitatively evaluated. Adsorption of dodecyl maltoside showed a maximum at certain mixing ratio at low pH (3{approx}5), while adsorption of dodecyl maltoside steadily decreased with the increase in C{sub 12}SO{sub 3}Na. Analytical ultracentrifuge technique was employed to study the micellization of DM/C{sub 12}SO{sub 3}Na mixtures. Compositional changes of the aggregates were observed the mixing ratio of the components. Surfactant mixture micellization affects the conformation and orientation of adsorption layer at mineral/water interface and thus the wettability and as a result, the oil release efficiency of the chemical flooding processes. A preliminary term, Reagent Loss Index (RLI), has been proposed to represent the adsorption of all the surfactants in a standardized framework for the development of the models. Previously reported adsorption data have been analyzed using the theoretical framework for the preparation of a guidebook to help optimization of chemical combinations and selection of reagent scheme for enhanced oil recovery.

  8. Effect of nonionic surfactant Brij 35 on the fate and transport of oxytetracycline antibiotic in soil.

    Science.gov (United States)

    Elsayed, Eman M; Prasher, Shiv O; Patel, Ramanbhai M

    2013-02-15

    In many parts of the world, river water is used for irrigation. Treated, partially treated, and even untreated water from wastewater treatment plants is discharged directly into rivers, thereby degrading the quality of the water. Consequently, irrigation water may contain surfactants which may affect the fate and transport of chemicals such as pesticides and antibiotics in agricultural soils. A field lysimeter study was undertaken to investigate the effect of the nonionic surfactant, Brij 35, on the fate and transport of an antibiotic, Oxytetracycline, commonly used in cattle farms. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 Mg m(-3). Cattle manure, containing Oxytetracycline, was applied at the surface of the lysimeters at the recommended rate of 10 t/ha. Each of three aqueous Brij 35 solutions, 0, 0.5 and 5 g L(-1) (i.e., 'good,' 'poor' and 'very poor' quality irrigation water) were each applied to the lysimeters in triplicate. Over a 90 day period, soil and leachate samples were collected and analyzed. Batch experiment results showed that the presence of the nonionic surfactant Brij 35 significantly reduced the sorption coefficient of OTC from 23.55 mL g(-1) in the aqueous medium to 19.49, 12.49 and 14.53 in the presence of Brij 35 at concentrations of 0.25, 2.5 and 5 g L(-1), respectively. Lysimeter results indicted the significant downward movement of OTC at depths of 60 cm into soil profile and leachate in the presence of surfactant. Thus, the reuse of wastewater containing surfactants might enhance the mobility of contaminants and increase ground water pollution.

  9. Sorption of a nonionic surfactant Tween 80 by minerals and soils

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Soyoung, E-mail: soyoung@pusan.ac.kr; Jeong, Hoon Young, E-mail: hjeong@pusan.ac.kr

    2015-03-02

    Highlights: • Tween 80 sorption varies significantly among soil minerals. • Sorption mechanisms and atomic compositions explain to mineral-specific sorption. • Clay minerals and SOM in soils are the key contributors to Tween 80 sorption. • Hysteresis suggests the potential difficulty in removing residual surfactants. - Abstract: Batch experiments were conducted to evaluate Tween 80 sorption by oxides, aluminosilicates, and soils. For oxides, the sorption by silica and alumina follow linear isotherms, and that by hematite follows a Langmuir isotherm. Considering isotherm type and surface coverage, Tween 80 may partition into the silica/alumina–water interface, whereas it may bind to hematite surface sites. Among aluminosilicates, montmorillonite shows the greatest sorption due to the absorption of Tween 80 into interlayers. For other aluminosilicates, it sorbs to surfaces, with the sorption increasing as plagioclase < vermiculite < kaolinite. This results from the relative reactivity among surface sites: ≡NaOH, ≡CaOH << ≡SiOH < ≡AlOH. Experiments using dry- and wet-sieved soils reveal that fine-grained clay minerals, difficult to separate by dry-sieving, contribute significantly to Tween 80 sorption. The greater sorption by untreated soils than H{sub 2}O{sub 2}-treated soils indicates that soil organic matter is a vital sorbent. The sorption hysteresis, contributed to by clay minerals and soil organic matter, is characterized by the greater sorption during the desorption than the sorption stages. This suggests the potential difficulty in removing surfactants from soils. Also, sorption of surfactants can adversely affect surfactant-enhanced remediation by decreasing the aquifer permeability and the availability of surfactants for micellar solubilization.

  10. 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.

  11. Interfacial mechanisms for stability of surfactant-laden films

    CERN Document Server

    Bhamla, M Saad; Alvarez-Valenzuela, Marco A; Tajuelo, Javier; Fuller, Gerald G

    2016-01-01

    Thin liquid films are central to everyday life. They are ubiquitous in modern technology (pharmaceuticals, coatings), consumer products (foams, emulsions) and also serve vital biological functions (tear film of the eye, pulmonary surfactants in the lung). A common feature in all these examples is the presence of surface-active molecules at the air-liquid interface. Though they form only molecularly-thin layers, these surfactants produce complex surface stresses on the free surface, which have important consequences for the dynamics and stability of the underlying thin liquid film. Here we conduct simple thinning experiments to explore the fundamental mechanisms that allow the surfactant molecules to slow the gravity-driven drainage of the underlying film. We present a simple model that works for both soluble and insoluble surfactant systems. We show that surfactants with finite surface rheology influence bulk flow through viscoelastic interfacial stresses, while surfactants with inviscid surfaces achieve stab...

  12. Estimation hydrophilic-lipophilic balance number of surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Pawignya, Harsa, E-mail: harsa-paw@yahoo.co.id [Chemical Engineering Department Diponegoro University (Indonesia); Chemical Engineering Departement University of Pembangunan Nasional Yogyakarta (Indonesia); Prasetyaningrum, Aji, E-mail: ajiprasetyaningrum@gmail.com; Kusworo, Tutuk D.; Pramudono, Bambang, E-mail: Pramudono2004@yahoo.com [Chemical Engineering Department Diponegoro University (Indonesia); Dyartanti, Endah R. [Chemical Engineering Department Diponegoro University (Indonesia); Chemical Enginering Departement Sebelas Maret University (Indonesia)

    2016-02-08

    Any type of surfactant has a hydrophilic-lipophilic balance number (HLB number) of different. There are several methods for determining the HLB number, with ohysical properties of surfactant (solubility cloud point and interfacial tension), CMC methods and by thermodynamics properties (Free energy Gibbs). This paper proposes to determined HLB numbers from interfelation methods. The result of study indicated that the CMC method described by Hair and Moulik espesially for nonionic surfactant. The application of exess Gibbs free energy and by implication activity coefficient provides the ability to predict the behavior of surfactants in multi component mixtures of different concentration. Determination of HLB number by solubility and cloud point parameter is spesific for anionic and nonionic surfactant but this methods not available for cationic surfactants.

  13. [Pulmonary surfactant homeostasis associated genetic abnormalities and lung diseases].

    Science.gov (United States)

    Jiang, Xiaojing; Sun, Xiuzhu; Du, Weihua; Hao, Haisheng; Zhao, Xueming; Wang, Dong; Zhu, Huabin; Liu, Yan

    2016-08-01

    Pulmonary surfactant (PS) is synthesized and secreted by alveolar epithelial type II (AEII) cells, which is a complex compound formed by proteins and lipids. Surfactant participates in a range of physiological processes such as reducing the surface tension, keeping the balance of alveolar fluid, maintaining normal alveolar morphology and conducting host defense. Genetic disorders of the surfactant homeostasis genes may result in lack of surfactant or cytotoxicity, and lead to multiple lung diseases in neonates, children and adults, including neonatal respiratory distress syndrome, interstitial pneumonia, pulmonary alveolar proteinosis, and pulmonary fibrosis. This paper has provided a review for the functions and processes of pulmonary surfactant metabolism, as well as the connection between disorders of surfactant homeostasis genes and lung diseases.

  14. Branched alkyl alcohol propoxylated sulfate surfactants for improved oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.; Iglauer, S.; Shuler, P.; Tang, Y. [California Institute of Technology, Covina, CA (US). Power, Environmental and Energy Research (PEER) Center; Goddard, W.A. III [California Institute of Technology, Pasadena, CA (United States). Materials and Process Simulation Center

    2010-05-15

    This investigation considers branched alkyl alcohol propoxylated sulfate surfactants as candidates for chemical enhanced oil recovery (EOR) applications. Results show that these anionic surfactants may be preferred candidates for EOR as they can be effective at creating low interfacial tension (IFT) at dilute concentrations, without requiring an alkaline agent or cosurfactant. In addition, some of the formulations exhibit a low IFT at high salinity, and hence may be suitable for use in more saline reservoirs. Adsorption tests onto kaolinite clay indicate that the loss of these surfactants can be comparable to or greater than other types of anionic surfactants. Surfactant performance was evaluated in oil recovery core flood tests. Selected formulations recovered 35-50% waterflood residual oil even with dilute 0.2 wt% surfactant concentrations from Berea sandstone cores. (orig.)

  15. Effects of silicon surfactant in rigid polyurethane foams

    Directory of Open Access Journals (Sweden)

    2008-03-01

    Full Text Available The rigid polyurethane foams (RPUFs have been fabricated from high functional crude 4,4’-di-phenylmethane diisocyanate (CMDI and polypropylene glycols (PPGs for a wide range of surfactant concentration with an environmently friendly blowing agent (HFC 365mfc. Cream time, gel time, and tack-free time increased with the addition of surfactant. Foam density decreased rapidly to a minimum at 0.5 pphp (part per hundred polyol surfactant due to the increased blowing efficiency with surfactant. Surface tension rapidly decreased to an asymptotic value at 2 pphp surfactant. In accordance with this, cell size decreased and closed cell content increased rapidly to constant values at low surfactant concentrations (<1 pphp. The decrease of cell size was accompanied by the decrease of thermal conductivity to give a linear relatiohship between the two implying that the series model of heat transfer is applicable.

  16. Gemini imidazolium surfactants: synthesis and their biophysiochemical study.

    Science.gov (United States)

    Kamboj, Raman; Singh, Sukhprit; Bhadani, Avinash; Kataria, Hardeep; Kaur, Gurcharan

    2012-08-21

    New gemini imidazolium surfactants 9-13 have been synthesized by a regioselective epoxy ring-opening reaction under solvent-free conditions. The surface properties of these new gemini surfactants were evaluated by surface tension and conductivity measurements. These surfactants have been found to have low critical micelle concentration (cmc) values as compared to other categories of gemini cationic surfactants and also showed the tendency to form premicellar aggregates in solution at sufficiently low concentration below their cmc values. The thermal degradation of these surfactants was determined by thermograviometry analysis (TGA). These new cationic surfactants have a good DNA binding capability as determined by agarose gel electrophoresis and ethidium bromide exclusion experiments. 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.

  17. 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...

  18. Interactions of surfactants with a water treatment protein from Moringa oleifera seeds in solution studied by zeta-potential and light scattering measurements.

    Science.gov (United States)

    Kwaambwa, Habauka M; Rennie, Adrian R

    2012-04-01

    Protein extracted from Moringa oleifera (MO) seeds has been advocated as a cheap and environmental friendly alternative to ionic flocculants for water purification. However, the nature and mechanism of its interaction with particles in water, as well as with dissolved surface-active molecules, are not well understood. In this article, we report studies of the protein and its interaction with four surfactants using dynamic light scattering (DLS), zeta-potential and turbidity measurements. Zeta-potential measurements identified points of charge reversal and the turbidity and DLS measurements were used to characterize the microstructure and size of protein-surfactant complexes. From the points of charge reversal, it was estimated that 7 anions are required to neutralize the positive charges of each protein molecule at pH 7. For protein mixtures with sodium dodecyl sulfate and dodecyl di-acid sodium salt, the peak in turbidity corresponds to concentrations with a large change in zeta-potential. No turbidity was observed for protein mixtures with either the nonionic surfactant Triton X-100 or the zwitterionic surfactant N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate. Changes of pH in the range 4-10 have little effect on the zeta-potential, turbidity, and the hydrodynamic radius reflecting the high isoelectric point of the protein. Addition of small amounts of salt has little effect on the size of protein in solution. These results are discussed in the context of the use of the MO protein in water treatment.

  19. 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.

  20. Workplace Charging. Charging Up University Campuses

    Energy Technology Data Exchange (ETDEWEB)

    Giles, Carrie [ICF International, Fairfax, VA (United States); Ryder, Carrie [ICF International, Fairfax, VA (United States); Lommele, Stephen [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-03-01

    This case study features the experiences of university partners in the U.S. Department of Energy's (DOE) Workplace Charging Challenge with the installation and management of plug-in electric vehicle (PEV) charging stations.

  1. The Role of Surfactant in Respiratory Distress Syndrome

    OpenAIRE

    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...

  2. [Liposome phospholipid substitution and lung function in surfactant deprived rats].

    Science.gov (United States)

    Obladen, M

    1985-01-01

    In vivo activity of an artificial surfactant was studied in surfactant depleted rats. After tenfold alveolar lavage, PaO2, tidal volume, and compliance of the respiratory system fell to one third of initial value. Substitution of large unilamellar vesicles containing 90% Dipalmitoylphosphatidylcholine and 10% unsaturated phosphatidylglycerol largely restored oxygenation and lung mechanics in most animals. Complete normalization with weaning from the ventilator, however, was achieved neither with liposomes nor with natural surfactant concentrate.

  3. Surfactant Based Enhanced Oil Recovery and Foam Mobility Control

    Energy Technology Data Exchange (ETDEWEB)

    George J. Hirasaki; Clarence A. Miller; Gary A. Pope

    2005-07-01

    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 combination of two surfactants was found to be particularly effective for application in carbonate formations at low temperature. A formulation has been designed for a particular field application. The addition of an alkali such as sodium carbonate makes possible in situ generation of surfactant and significant reduction of surfactant adsorption. In addition to reduction of interfacial tension to ultra-low values, surfactants and alkali can be designed to alter wettability to enhance oil recovery. The design of the process to maximize the region of ultra-low IFT is more challenging since the ratio of soap to synthetic surfactant is a parameter in the conditions for optimal salinity. Compositional simulation of the displacement process demonstrates the interdependence of the various components for oil recovery. An alkaline surfactant process is designed to enhance spontaneous imbibition in fractured, oil-wet, carbonate formations. It is able to recover oil from dolomite core samples from which there was no oil recovery when placed in formation brine. Mobility control is essential for surfactant EOR. Foam is evaluated to improve the sweep efficiency of surfactant injected into fractured reservoirs. UTCHEM is a reservoir simulator specially designed for surfactant EOR. It has been modified to represent the effects of a change in wettability. Simulated case studies demonstrate the effects of wettability.

  4. Adsorption kinetics of surfactants at liquid-solid and liquid-vapor interfaces from atomic-scale simulations

    Science.gov (United States)

    Iskrenova, Eugeniya K.; Patnaik, Soumya S.

    2012-02-01

    Nucleate pool boiling of pure liquid is a complex process involving different size- and time-scale phenomena. The appearance of the first nanobubble in the liquid at the bottom of a hot pan, the detachment of the bubble from the solid surface, its subsequent coalescence with other bubbles, all represent complex multiscale phenomena. Surfactants added to water increase the complexity of the process by contributing to the dynamic surface tension at the liquid-vapor and liquid-solid interfaces and thus affecting the heat and mass transfer at those interfaces. We apply molecular dynamics simulations to study the adsorption kinetics of anionic, cationic, and non-ionic surfactants at liquid/solid and liquid/vapor interfaces. The all-atom vs. united-atom approaches for the solid and surfactants are surveyed in view of their applicability at near boiling temperatures and a range of model water potentials is assessed for reproducing the thermal properties of water at boiling conditions.

  5. A Glimpse of Our Journey into the Design of Optical Probes in Self-assembled Surfactant Aggregates.

    Science.gov (United States)

    Dey, Nilanjan; Bhattacharya, Santanu

    2016-08-01

    Dynamic self-assembling amphiphilic surfactant molecules, popularly known as "micelles", have received widespread attention, due to their ability to modulate the photophysical properties of various organic dyes upon encapsulation. Along with their well-known use as cleaning agents, catalysts in organic reactions, and even for drug delivery purposes, these surfactant assemblies also show promising pertinence in the recognition of both ionic and nonionic targeted analytes. Low micropolarity and relatively hydrophobic environments promote their interaction with ionic analytes, whereas neutral species mostly affect the aggregation pattern of the probe molecules upon partitioning inside the micellar hydrophobic milieu. The environment-sensitive nature of micelle-based self-assembled probes also prompts us to devise new sensor arrays for the recognition of multiple analytes. While this account will largely focus on our own work in developing surfactant-triggered self-assembled sensors, our findings have been placed in the context of the relevant contributions from others during their strategic evolution.

  6. 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.

  7. Effect of dielectric fluid with surfactant and graphite powder on Electrical Discharge Machining of titanium alloy using Taguchi method

    Directory of Open Access Journals (Sweden)

    Murahari Kolli

    2015-12-01

    Full Text Available In this paper, Taguchi method was employed to optimize the surfactant and graphite powder concentration in dielectric fluid for the machining of Ti-6Al-4V using Electrical Discharge Machining (EDM. The process parameters such as discharge current, surfactant concentration and powder concentration were changed to explore their effects on Material Removal Rate (MRR, Surface Roughness (SR, Tool wear rate (TWR and Recast Layer Thickness (RLT. Detailed analysis of structural features of machined surface was carried out using Scanning Electron Microscope (SEM to observe the influence of surfactant and graphite powder on the machining process. It was observed from the experimental results that the graphite powder and surfactant added dielectric fluid significantly improved the MRR, reduces the SR, TWR and RLT at various conditions. Analysis of Variance (ANOVA and F-test of experimental data values related to the important process parameters of EDM revealed that discharge current and surfactant concentration has more percentage of contribution on the MRR and TWR whereas the SR, and RLT were found to be affected greatly by the discharge current and graphite powder concentration.

  8. Biocidal and inhibitory activity screening of de novo synthesized surfactants against two eukaryotic and two prokaryotic microbial species.

    Science.gov (United States)

    Tiecco, Matteo; Cardinali, Gianluigi; Roscini, Luca; Germani, Raimondo; Corte, Laura

    2013-11-01

    Thirty-six quaternary ammonium salts, of which 28 structurally different non-commercially available surfactants, were tested to screen their biocidal and inhibitory antimicrobial activity. Their activity was compared to commercially available amphiphiles as well as to non-amphiphilic quaternary ammonium salts. As target of these compounds four microbial species were employed of which two (Saccharomyces cerevisiae and Candida albicans) were important yeast in the food and clinical environment and the other two (Escherichia coli and Listeria innocua) represented the Gram negative and positive bacteria, respectively. The surfactants showed the ability to kill the microbial cells in water solution and to variably hamper their growth onto agar medium. The non-amphiphilic compounds (which represent analogues of some surfactants used in this study, since they have the same head group but no hydrophobic portion) had little effect in solution and no effect against the microbial growth on plate. Amphoteric and non-amphoteric zwitterionic surfactants showed reduced biocidal activity. The most active antimicrobial agent was N-tetradecyltropinium bromide (23S) surfactant. The presence of cells did not significantly affect the ability to form micelles, as demonstrated by comparative conductometric measurements.

  9. Interfacial tension in oil-water-surfactant systems: on the role of intra-molecular forces on interfacial tension values using DPD simulations.

    Science.gov (United States)

    Deguillard, E; Pannacci, N; Creton, B; Rousseau, B

    2013-04-14

    We have computed interfacial tension in oil-water-surfactant model systems using dissipative particle dynamics (DPD) simulations. Oil and water molecules are modelled as single DPD beads, whereas surfactant molecules are composed of head and tail beads linked together by a harmonic potential to form a chain molecule. We have investigated the influence of the harmonic potential parameters, namely, the force constant K and the equilibrium distance r0, on the interfacial tension values. For both parameters, the range investigated has been chosen in agreement with typical values in the literature. Surprisingly, we observe a large effect on interfacial tension values, especially at large surfactant concentration. We demonstrate that, due to a subtle balance between intra-molecular and inter-molecular interactions, the local structure of surfactants at the oil-water interface is modified, the interfacial tension is changed and the interface stability is affected.

  10. Effects of Surfactant Adsorption on Surficial Wettability of Nonwoven Fabrics

    Institute of Scientific and Technical Information of China (English)

    CAI Bing; TANG Bing; LI Rui-xia; WU Da-cheng

    2002-01-01

    All types of surfactants (cationic, anionic and nonionic)reported in this paper could enhance the surficiai wettability of polypropylene (PP) and polyethylene terephthalate (PET) nonwoven fabrics. However, the effects of cationic and nonionic surfactants were better.The longer the treatment time of surfactants on the nonwoven fabrics, the better the surficial wettability.The surficial rewetting time would no longer change above a certain treatment time. The rewettability of nonwoven fabrics could be evidently improved just when the concentration of surfactants was just above the CMC,except for sodium dodecylbenzene sulfonate (LAS). The finer the fibers and the looser the structures, the better the surficial rewettability of nonwoven fabrics.

  11. AARC Clinical Practice Guideline. Surfactant replacement therapy: 2013.

    Science.gov (United States)

    Walsh, Brian K; Daigle, Brandon; DiBlasi, Robert M; Restrepo, Ruben D

    2013-02-01

    We searched the MEDLINE, CINAHL, and Cochrane Library databases for English-language randomized controlled trials, systematic reviews, and articles investigating surfactant replacement therapy published between January 1990 and July 2012. By inspection of titles, references having no relevance to the clinical practice guideline were eliminated. The update of this clinical practice guideline is based on 253 clinical trials and systematic reviews, and 12 articles investigating surfactant replacement therapy. The following recommendations are made following the Grading of Recommendations Assessment, Development, and Evaluation scoring system: 1: Administration of surfactant replacement therapy is strongly recommended in a clinical setting where properly trained personnel and equipment for intubation and resuscitation are readily available. 2: Prophylactic surfactant administration is recommended for neonatal respiratory distress syndrome (RDS) in which surfactant deficiency is suspected. 3: Rescue or therapeutic administration of surfactant after the initiation of mechanical ventilation in infants with clinically confirmed RDS is strongly recommended. 4: A multiple surfactant dose strategy is recommended over a single dose strategy. 5: Natural exogenous surfactant preparations are recommended over laboratory derived synthetic suspensions at this time. 6: We suggest that aerosolized delivery of surfactant not be utilized at this time.

  12. STRUCTURE AND MORPHOLOGY CHANGES OF HYDROBIOTITES MODIFIED BY CATIONIC SURFACTANTS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this study, X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) together with Scanning probe microscopy (SPM) were used to characterize the structure and morphology of the complexes, where the hydrobiotites (Xinjiang) were modified by single-chain surfactants octyltrimethylammonium bromide (OTMA) and octadecyltrimethylammonium bromide (ODTMA). XRD patterns showed that the structure of complexes was significantly influenced by the surfactant concentration and the alkyl chain length, because obvious changes took place in the basal spacing. Furthermore, according to the XRD results, several arrangements of surfactant molecules within the hydrobiotite interlayer space were deduced. The FTIR spectrum indicated that the surfactant contents in complexes dramatically increased with the alkyl chain length. The SPM micrographs demonstrated that the surfaces of complexes prepared at lower surfactant concentration were relatively flat compared with that prepared at higher concentration, while those with higher surfactant concentration had much steeper surface due to the alkyl chain length. It was concluded that structure and morphology of surfactant/hydrobiotite complexes depend not only on the surfactant concentration, but also strongly on the surfactant species.

  13. Interactions in Calcium Oxalate Hydrate/Surfactant Systems.

    Science.gov (United States)

    Sikiric; Filipovic-Vincekovic; Babic-Ivancić Vdović Füredi-Milhofer

    1999-04-15

    Phase transformation of calcium oxalate dihydrate (COD) into the thermodynamically stable monohydrate (COM) in anionic (sodium dodecyl sulfate (SDS)) and cationic (dodecylammonium chloride) surfactant solutions has been studied. Both surfactants inhibit, but do not stop transformation from COD to COM due to their preferential adsorption at different crystal faces. SDS acts as a stronger transformation inhibitor. The general shape of adsorption isotherms of both surfactants at the solid/liquid interface is of two-plateau-type, but differences in the adsorption behavior exist. They originate from different ionic and molecular structures of crystal surfaces and interactions between surfactant headgroups and solid surface. Copyright 1999 Academic Press.

  14. Effect of surfactants on Ra-sHSPI - A small heat shock protein from the cattle tick Rhipicephalus annulatus

    Science.gov (United States)

    Siddiqi, Mohammad Khursheed; Shahein, Yasser E.; Hussein, Nahla; Khan, Rizwan H.

    2016-09-01

    Electrostatic interaction plays an important role in protein aggregation phenomenon. In this study, we have checked the effect of anionic - Sodium Dodecyl Sulfate (SDS) and cationic-Cetyltrimethyl Ammonium Bromide (CTAB) surfactant on aggregation behavior of Ra-sHSPI, a small heat shock protein purified from Rhipicephalus annulatus tick. To monitor the effect of these surfactants, we have employed several spectroscopic methods such as Rayleigh light scattering measurements, ANS (8-Anilinonaphthalene-1-sulfonic acid) fluorescence measurements, ThT (Thioflavin T) binding assays, Far-UV CD (Circular Dichroism) and dynamic light scattering measurements. In the presence of anionic surfactant-SDS, Ra-sHSPI forms amyloid fibrils, in contrast, no amyloid formation was observed in presence of cationic surfactant at low pH. Enhancement of ANS fluorescence intensity confirms the exposition of more hydrophobic patches during aggregation. ThT binding assay confirms the amyloid fibrillar nature of the SDS induced Ra-sHSPI aggregates and supported by PASTA 2.0 (prediction of amyloid structural aggregation) software. This study demonstrates the crucial role of charge during amyloid fibril formation at low pH in Ra-sHSPI.

  15. 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...

  16. Surfactant-controlled composition and crystal structure of manganese(II sulfide nanocrystals prepared by solvothermal synthesis

    Directory of Open Access Journals (Sweden)

    Elena Capetti

    2015-12-01

    Full Text Available We investigated how the outcome of the solvothermal synthesis of manganese(II sulfide (MnS nanocrystals (NCs is affected by the type and amount of long chain surfactant present in the reaction mixture. Prompted by a previous observation that a larger than stoichiometric amount of sulfur is required [Puglisi, A.; Mondini, S.; Cenedese, S.; Ferretti, A. M.; Santo, N.; Ponti A. Chem. Mater. 2010, 22, 2804–2813], we carried out a wide set of reactions using Mn(II carboxylates and Mn2(CO10 as precursors with varying amounts of sulfur and carboxylic acid. MnS NCs were obtained provided that the S/Mn ratio was larger than the L/Mn ratio, otherwise MnO NCs were produced. Since MnS can crystallize in three distinct phases (rock salt α-MnS, zincblende β-MnS, and wurtzite γ-MnS, we also investigated whether the surfactant affected the NC polymorphism. We found that MnS polymorphism can be controlled by appropriate selection of the surfactant. γ-MnS nanocrystals formed when a 1:2 mixture of long chain carboxylic acid and amine was used, irrespective of the presence of carboxylic acid as a free surfactant or ligand in the metal precursor. When we used a single surfactant (carboxylic acid, alcohol, thiol, amine, α-MnS nanocrystals were obtained. The peculiar role of the amine seems to be related to its basicity. The nanocrystals were characterized by TEM and electron diffraction; ATR-FTIR spectroscopy provided information about the surfactants adsorbed on the NCs.

  17. C-reactive protein increases membrane fluidity and distorts lipid lateral organization of pulmonary surfactant. Protective role of surfactant protein A

    DEFF Research Database (Denmark)

    Saenz, Alejandra; Lopez-Sanchez, Almudena; Mojica-Lazaro, Jonas

    2010-01-01

    The purpose of this study was to investigate how surfactant membranes can be perturbed by C-reactive protein (CRP) and whether surfactant protein A (SP-A) might overcome CRP-induced surfactant membrane alterations. The effect of CRP on surfactant surface adsorption was evaluated in vivo after int...

  18. Biomarker analysis of liver cells exposed to surfactant-wrapped and oxidized multi-walled carbon nanotubes (MWCNTs)

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, W. Matthew, E-mail: Henderson.Matt@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, 960 College Station Road, Athens 30605, GA (United States); Bouchard, Dermont [U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, 960 College Station Road, Athens 30605, GA (United States); Chang, Xiaojun [Grantee to U.S. Environmental Protection Agency via National Research Council Cooperative Agreement, Athens 30605, GA (United States); Al-Abed, Souhail R. [U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 Martin Luther King Dr. W, Cincinnati, OH 45268 (United States); Teng, Quincy [U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, 960 College Station Road, Athens 30605, GA (United States)

    2016-09-15

    Carbon nanotubes (CNTs) have great potential in industrial, consumer, and mechanical applications, based partly on their unique structural, optical and electronic properties. CNTs are commonly oxidized or treated with surfactants to facilitate aqueous solution processing, and these CNT surface modifications also increase possible human and ecological exposures to nanoparticle-contaminated waters. To determine the exposure outcomes of oxidized and surfactant-wrapped multiwalled carbon nanotubes (MWCNTs) on biochemical processes, metabolomics-based profiling of human liver cells (C3A) was utilized. Cells were exposed to 0, 10, or 100 ng/mL of MWCNTs for 24 and 48 h; MWCNT particle size distribution, charge, and aggregation were monitored concurrently during exposures. Following MWCNT exposure, cellular metabolites were extracted, lyophilized, and buffered for {sup 1}H NMR analysis. Acquired spectra were subjected to both multivariate and univariate analysis to determine the consequences of nanotube exposure on the metabolite profile of C3A cells. Resulting scores plots illustrated temporal and dose-dependent metabolite responses to all MWCNTs tested. Loadings plots coupled with t-test filtered spectra identified metabolites of interest. XPS analysis revealed the presence of hydroxyl and carboxyl functionalities on both MWCNTs surfaces. Metal content analysis by ICP-AES indicated that the total mass concentration of the potentially toxic impurities in the exposure experiments were extremely low (i.e. [Ni] ≤ 2 × 10{sup −10} g/mL). Preliminary data suggested that MWCNT exposure causes perturbations in biochemical processes involved in cellular oxidation as well as fluxes in amino acid metabolism and fatty acid synthesis. Dose-response trajectories were apparent and spectral peaks related to both dose and MWCNT dispersion methodologies were determined. Correlations of the significant changes in metabolites will help to identify potential biomarkers associated with

  19. Multiwalled Carbon Nanotube Dispersion Methods Affect Their Aggregation, Deposition, and Biomarker Response

    Science.gov (United States)

    To systematically evaluate how dispersion methods affect the environmental behaviors of multiwalled carbon nanotubes (MWNTs), MWNTs were dispersed in various solutions (e.g., surfactants, natural organic matter (NOM), and etc.) via ultrasonication (SON) and long-term stirring (LT...

  20. Anionic Polyelectrolyte-Cationic Surfactant Interactions in Aqueous Solutions and Foam Films Stability Interactions entre polyélectrolytes anioniques et tensioactifs cationiques en solutions aqueuses et stabilité des films de mousses

    Directory of Open Access Journals (Sweden)

    Langevin D.

    2006-12-01

    Full Text Available The objective of this work is to study polymer/surfactant interactions in aqueous solution and at the air/water interface. These interations are involved in many physicochemical phenomena, such as colloidal stabilization and wettability which are of major importance in oil application as for exemple drilling muds. More precisely, we have attempted to characterize interactions between a non surface active anionic copolymer (acrylamide/acrylamide sulfonate and an oppositely charged cationic surfactant (C12 TAB. Our results show a synergestic surface tension lowering (coadsorption at extremely low surfactant concentrations (10 to the power of (-3 to 10 to the power of (-1 CMC. At higher concentrations, namely above the so called Critical Aggregation Concentration (CAC, polymer-surfactant complexes form in the bulk and the macromolecules precipitate out of the solution. Foam films made from these mixed solutions are stable while C12TAB films are unstable. Disjoining pressure measurements on mixed films with surfactant concentration two orders of magnitude below the CAC show the existence of long range repulsive forces and a discrete film thickness transition. At the CAC, we obtain mixed films with gel-like networks that are strongly affected by the film thinning rate. L'objectif de cette étude est d'étudier les interactions polymère/tensioactif en solution aqueuse et à l'interface eau/air. Ces interactions interviennent dans de nombreux phénomènes physico-chimiques tels que la stabilisation de suspensions colloïdales et la mouillabilité qui sont d'une importance majeure dans les applications pétrolières comme, par exemple, les boues de forage. Plus précisément, nous avons essayé de caractériser les interactions entre un copolymère anionique n'ayant pas d'activité de surface (acrylamide/acrylamide sulfoné avec un tensioactif de charge opposée cationique (C12TAB. Nos résultats montrent une diminution synergique de la tension

  1. Enriched surface acidity for surfactant-free suspensions of carboxylated carbon nanotubes purified by centrifugation

    Directory of Open Access Journals (Sweden)

    Elizabeth I. Braun

    2016-06-01

    Full Text Available It is well known that surfactant-suspended carbon nanotube (CNT samples can be purified by centrifugation to decrease agglomerates and increase individually-dispersed CNTs. However, centrifugation is not always part of protocols to prepare CNT samples used in biomedical applications. Herein, using carboxylated multi-walled CNTs (cMWCNTs suspended in water without a surfactant, we developed a Boehm titrimetric method for the analysis of centrifuged cMWCNT suspensions and used it to show that the surface acidity of oxidized carbon materials in aqueous cMWCNT suspensions was enriched by ∼40% by a single low-speed centrifugation step. This significant difference in surface acidity between un-centrifuged and centrifuged cMWCNT suspensions has not been previously appreciated and is important because the degree of surface acidity is known to affect the interactions of cMWCNTs with biological systems.

  2. Mesoporous Silica Materials Synthesized via Sol-Gel Methods Modified with Ionic Liquid and Surfactant Molecules

    Institute of Scientific and Technical Information of China (English)

    Cun-ying Xu; Ru-lan Tang; Yi-xin Hu; Peng-xiang Zhang

    2008-01-01

    Mesoporous silica materials were synthesized via a sol-gel method employing a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4]) as a new solvent medium and further modified with surfactant (hexadecyl-trimethyl-ammonium bromide, CTAB) as a pore templating material. The synthesized samples were characterized by the transmission electron microscopy, X-ray diffraction, and N2 adsorption-desorption techniques. The results indicated that the mesoporous silica synthesized by using [bmim][BF4] and CTAB as mixed templates showed better mesostructural order and smaller pore size, compared with mesoporous silica materials synthesized by using single [bmim][BF4]as template under the same conditions. This indicates that the presence of surfactant can affect the microstructures of silica prepared by the present synthesis method.

  3. Development of alkaline/surfactant/polymer (ASP flooding technology for recovery of Karazhanbas oil

    Directory of Open Access Journals (Sweden)

    Birzhan Zhappasbaev

    2016-03-01

    Full Text Available The tertiary oil recovery methods like alkaline, surfactant and polymer (ASP flooding are very perspective in order to achieve the synergetic effect out of the different impacts which are caused by these chemicals, which affect oil and water filtration in the reservoir and increase oil recovery. In this communication, we consider the applicability of hydrophobically modified polyampholyte – poly(hexadecylaminocrotonatebetaine (PHDACB as ASP flooding agent for recovery of oil from Karazhanbas oilfield. As “polysoap”, the aqueous solution of PHDACB dissolved in aqueous KOH was used. This system combines the advantages of alkaline, surfactant and polymer and exhibits the synergistic effect. The laboratory results showed that the ASP flooding considerably increases the oil recovery in addition to water flooding. In perspective, the ASP flooding may substitute the steam injection and other thermal enhanced oil recovery (EOR technologies.

  4. Novel Highly Flexible Wormlike Micelles Formed by Cetylpyridinium Chloride and Trioxyethylene Monododecyl Ether Surfactants

    Directory of Open Access Journals (Sweden)

    Firoz Kapadia

    2014-06-01

    Full Text Available The impact of small nonionic hydrophobic molecule, trioxyethylene monododecyl ether (C12EO3, on the viscoelastic properties of aqueous solutions of cetylpyridinium chloride (CPC is studied. As the C12EO3 concentration increases, the viscosity passes through a maximum. Dynamic rheological measurements revealed a comprehensive picture of how C12EO3 affects the different length scales in the entangled wormlike micelles. Increase in the viscosity can normally be caused by insertion of amphiphilic C12EO3 molecules into the cationic surfactant (CPC layer, or micellar swelling, caused by solubilization of very hydrophobic molecules in the micellar core. The partial phase behavior and rheology of this mixed surfactant systems is studied.

  5. Enhanced production of erythritol and mannitol by Yarrowia lipolytica in media containing surfactants.

    Science.gov (United States)

    Rakicka, Magdalena; Rywińska, Anita; Cybulski, Krzysztof; Rymowicz, Waldemar

    2016-01-01

    Various chemical compounds, including surfactants, when introduced to culture media may increase the permeability of cellular membranes and thereby affect the quantity of metabolites excreted by cells. The aim of the present study was to evaluate the impact of detergents including Triton X-100, Span 20 and Tween 80 on erythritol production from glycerol by Yarrowia lipolytica Wratislavia K1 in a shake-flask experiment, batch and fed-batch cultures. When Span 20 was added to a fed-batch culture with glycerol as a carbon source (300gL(-1)), erythritol production increased by 15% compared to the culture without the surfactant where it reached 142gL(-1) after 5 days, which corresponded to 0.47gg(-1) yield and productivity of 1.1gL(-1)h(-1). Therefore, it was concluded that Span 20 considerably enhanced the production of this polyol from glycerol.

  6. When Charged Black Holes Merge

    Science.gov (United States)

    Kohler, Susanna

    2016-08-01

    Most theoretical models assume that black holes arent charged. But a new study shows that mergers of charged black holes could explain a variety of astrophysical phenomena, from fast radio bursts to gamma-ray bursts.No HairThe black hole no hair theorem states that all black holes can be described by just three things: their mass, their spin, and their charge. Masses and spins have been observed and measured, but weve never measured the charge of a black hole and its widely believed that real black holes dont actually have any charge.That said, weve also never shown that black holes dont have charge, or set any upper limits on the charge that they might have. So lets suppose, for a moment, that its possible for a black hole to be charged. How might that affect what we know about the merger of two black holes? A recent theoretical study by Bing Zhang (University of Nevada, Las Vegas) examines this question.Intensity profile of a fast radio burst, a sudden burst of radio emission that lasts only a few milliseconds. [Swinburne Astronomy Productions]Driving TransientsZhangs work envisions a pair of black holes in a binary system. He argues that if just one of the black holes carries charge possibly retained by a rotating magnetosphere then it may be possible for the system to produce an electromagnetic signal that could accompany gravitational waves, such as a fast radio burst or a gamma-ray burst!In Zhangs model, the inspiral of the two black holes generates a global magnetic dipole thats perpendicular to the plane of the binarys orbit. The magnetic flux increases rapidly as the separation between the black holes decreases, generating an increasingly powerful magnetic wind. This wind, in turn, can give rise to a fast radio burst or a gamma-ray burst, depending on the value of the black holes charge.Artists illustration of a short gamma-ray burst, thought to be caused by the merger of two compact objects. [ESO/A. Roquette]Zhang calculates lower limits on the charge

  7. Surfactant enhanced disinfection of the human norovirus surrogate, tulane virus with organic acids and surfactant

    Science.gov (United States)

    Human infection with foodborne viruses can occur following consumption of contaminated food, person-to-person body contact, or release of aerosols. Combinatorial treatments of surfactants and organic acids may have synergistic or additive mechanisms to inactivate foodborne viruses and prevent outbr...

  8. Synthesis and characterization of zeolite from coal ashes modified by cationic surfactant; Sintese e caracterizacao de zeolita de cinzas de carvao modificada por surfactante cationico

    Energy Technology Data Exchange (ETDEWEB)

    Fungaro, D.A.; Borrely, S.I., E-mail: dfungaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-01-15

    Zeolite synthesized from coal fly ash was modified with different concentrations (2 and 20 mmol.L{sup -1}) of hexadecyltrimethylammonium bromide (HDTMA-Br). The Non-Modified Zeolite (NMZ) and Surfactant-Modified Zeolites (SMZ) were characterized by X-ray fluorescence spectrometry, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, thermogravimetric analysis, among others. The SMS presented negative charge probably due to the formation of a partial bilayer of HDTMA on exchangeable active sites on the external surface of NMZ. A decrease in surface area was observed for SMZ as compared to NMZ indicating zeolite surface coverage with HDTMA-Br molecules. The crystalline nature of the zeolite remained intact after adsorption of surfactant and heating for drying. FTIR analysis indicated that there were no significant changes in the structure of the zeolite after adsorption of surfactant. (author)

  9. Giant extracellular Glossoscolex paulistus Hemoglobin (HbGp) upon interaction with cethyltrimethylammonium chloride (CTAC) and sodium dodecyl sulphate (SDS) surfactants: Dissociation of oligomeric structure and autoxidation.

    Science.gov (United States)

    Santiago, Patricia S; Moreira, Leonardo M; de Almeida, Erika V; Tabak, Marcel

    2007-04-01

    The effects of two ionic surfactants on the oligomeric structure of the giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) in the oxy - form have been studied through the use of several spectroscopic techniques such as electronic optical absorption, fluorescence emission, light scattering, and circular dichroism. The use of anionic sodium dodecyl sulphate (SDS) and cationic cethyltrimethyl ammonium chloride (CTAC) has allowed to differentiate the effects of opposite headgroup charges on the oligomeric structure dissociation and hemoglobin autoxidation. At pH 7.0, both surfactants induce the protein dissociation and a significant oxidation. Spectral changes occur at very low CTAC concentrations suggesting a significant electrostatic contribution to the protein-surfactant interaction. At low protein concentration, 0.08 mg/ml, some light scattering within a narrow CTAC concentration range occurs due to protein-surfactant precipitation. Light scattering experiments showed the dissociation of the oligomeric structure by SDS and CTAC, and the effect of precipitation induced by CTAC. At higher protein concentrations, 3.0 mg/ml, a precipitation was observed due to the intense charge neutralization upon formation of ion pair in the protein-surfactant precipitate. The spectral changes are spread over a much wider SDS concentration range, implying a smaller electrostatic contribution to the protein-surfactant interactions. The observed effects are consistent with the acid isoelectric point (pI) of this class of hemoglobins, which favors the intense interaction of HbGp with the cationic surfactant due to the existence of excess acid anionic residues at the protein surface. Protein secondary structure changes are significant for CTAC at low concentrations while they occur at significantly higher concentrations for SDS. In summary, the cationic surfactant seems to interact more strongly with the protein producing more dramatic spectral changes as compared to the

  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...... are possible contributors to the pathogenesis of pulmonary alveolar proteinosis. Molecular dynamics simulations using the NAMD2 package were performed for systems containing from one to seven SP-C molecules to study their behavior in water. The results of our simulations show that unfolding of the protein...

  11. Porcine lung surfactant protein B gene (SFTPB)

    DEFF Research Database (Denmark)

    Cirera Salicio, Susanna; Fredholm, Merete

    2008-01-01

    The porcine surfactant protein B (SFTPB) is a single copy gene on chromosome 3. Three different cDNAs for the SFTPB have been isolated and sequenced. Nucleotide sequence comparison revealed six nonsynonymous single nucleotide polymorphisms (SNPs), four synonymous SNPs and an in-frame deletion of 69...... bp in the region coding for the active protein. Northern analysis showed lung-specific expression of three different isoforms of the SFTPB transcript. The expression level for the SFTPB gene is low in 50 days-old fetus and it increases during lung development. Quantitative real-time polymerase chain...

  12. 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.

  13. 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.

  14. Adsorption of polyelectrolytes and polyelectrolytes-surfactant mixtures at surfaces: a physico-chemical approach to a cosmetic challenge.

    Science.gov (United States)

    Llamas, Sara; Guzmán, Eduardo; Ortega, Francisco; Baghdadli, Nawel; Cazeneuve, Colette; Rubio, Ramón G; Luengo, Gustavo S

    2015-08-01

    The use of polymer and polymer - surfactant mixtures for designing and developing textile and personal care cosmetic formulations is associated with various physico-chemical aspects, e.g. detergency and conditioning in the case of hair or wool, that determine their correct performances in preserving and improving the appearance and properties of the surface where they are applied. In this work, special attention is paid to the systems combining polycations and negatively charged surfactants. The paper introduces the hair surface and presents a comprehensive review of the adsorption properties of these systems at solid-water interfaces mimicking the negative charge and surface energy of hair. These model surfaces include mixtures of thiols that confer various charge densities to the surface. The kinetics and factors that govern the adsorption are discussed from the angle of those used in shampoos and conditioners developed by the cosmetic industry. Finally, systems able to adsorb onto negatively charged surfaces regardless of the anionic character are presented, opening new ways of depositing conditioning polymers onto keratin substrates such as hair.

  15. Endogenous surfactant turnover in preterm infants measured with stable isotopes

    NARCIS (Netherlands)

    J.E.H. Bunt (Jan Erik); L.J.I. Zimmermann (Luc); J.L.D. Wattimena (Josias); R.H.Th. van Beek (Ron); P.J.J. Sauer (Pieter); V.P. Carnielli (Virgilio)

    1998-01-01

    textabstractWe studied surfactant synthesis and turnover in vivo in preterm infants using the stable isotope [U-13C]glucose, as a precursor for the synthesis of palmitic acid in surfactant phosphatidylcholine (PC). Six preterm infants (birth weight, 916 +/- 244 g; gesta

  16. Coupled Transport of PAH and Surfactants in Natural Aquifer Material

    Science.gov (United States)

    Danzer, J.; Grathwohl, P.

    1998-03-01

    Surfactants in aqueous solution adsorb onto mineral surfaces and form micelles above the critical micelle concentration (CMC) due to their physico-chemical properties. Hydrophobic organic compounds such as polycyclic aromatic hydrocarbons (PAHs) have a high affinity for the adsorbed surfactant layers (monomers, hemimicelles and admicelles) and to the micelles in the mobile aqueous phase. The transport of PAHs is controlled by the concentration of the surfactant and the partition coefficients, of the PAHs between water and admicelles (adsolubilization: K adm) and water and micelles (solubilization: K mic), respectively. These partition coefficients were measured in laboratory batch and column experiments using phenanthrene as a chemical probe for the PAHs, a non-ionic surfactant (Terrasurf G50), natural aquifer sand (River Neckar Alluvium: RNA) and its petrographic subcomponents. The sorption of the surfactant can be described by a linear isotherm for concentrations below the CMC and a sorption maximum above the CMC, which both depend on the grain size and the surfactant accessible internal surface area of the particles. K adm was found to be higher than K mic. Both depend on the surfactant's properties, such as alkyl chain length, polar headgroup or ethoxylation. In column experiments an increasing retardation of phenanthrene was observed up to the CMC followed by a facilitated transport at surfactant concentration several times the CMC.

  17. 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

  18. 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.

  19. Enrichment of surfactant from its aqueous solution using ultrasonic atomization.

    Science.gov (United States)

    Takaya, Haruko; Nii, Susumu; Kawaizumi, Fumio; Takahashi, Katsuroku

    2005-08-01

    Dilute aqueous solutions of dodecyl-benzenesulfonic acid sodium salt (DBS-Na) and polyoxyethylenenonylphenyl ethers (PONPEs) were ultrasonically atomized. The surfactants were concentrated in collected mist droplets. The enrichment ratio increased with decreasing surfactant concentration. Depending on the surfactant's molecular weight and affinity to water, different enrichment ratio was observed in the range of low feed concentrations. For anionic surfactant, DBS-Na, the enrichment ratio was significantly improved by KCl addition and a peak appeared on the plot of the ratio against KCl concentration. Addition of NaCl or CaCl2 . 2H2O to the surfactant solution also enhanced the enrichment ratio; however, the effect was relatively small. Such behaviors of the ratio were interpreted as enhanced interfacial adsorption of the surfactant and a lack of supply of surfactant monomers from liquid bulk because of slow breaking of surfactant micelles. Time required for collecting an amount of mist was also observed. Among the three salt systems, the time for KCl system was twice as long as others. This fact suggested that the formation of smaller droplets in KCl system.

  20. Physical principles for developing a synthetic lung surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Jaehnig, F. (Max-Planck-Institut fuer Biologie, Tuebingen (Germany, F.R.)); Obladen, M. (Tuebingen Univ. (Germany, F.R.). Kinderklinik)

    1984-01-01

    The physical principles for developing a synthetic lung surfactant to treat the respiratory distress syndrome are discussed. Requirements for the lipid composition and preparation of the synthetic surfactant are detailed, leading to the conclusion that a suspension of large unilamellar vesicles consisting of dipalmitoylphosphatidylcholine and a small amount of unsaturated lipid is a promising choice.

  1. Study of surfactant-skin interactions by skin impedance measurements.

    Science.gov (United States)

    Lu, Guojin; Moore, David J

    2012-02-01

    The stratum corneum (SC) plays a very critical physiological role as skin barrier in regulating water loss through the skin and protects the body from a wide range of physical and chemical exogenous insults. Surfactant-containing formulations can induce skin damage and irritation owing to surfactant absorption and penetration. It is generally accepted that reduction in skin barrier properties occurs only after surfactants have penetrated/permeated into the skin barrier. To mitigate the harshness of surfactant-based cleansing products, penetration/permeation of surfactants should be reduced. Skin impedance measurements have been taken in vitro on porcine skin using vertical Franz diffusion cells to investigate the impact of surfactants, temperature and pH on skin barrier integrity. These skin impedance results demonstrate excellent correlation with other published methods for assessing skin damage and irritation from different surfactant chemistry, concentration, pH, time of exposure and temperature. This study demonstrates that skin impedance can be utilized as a routine approach to screen surfactant-containing formulations for their propensity to compromise the skin barrier and hence likely lead to skin irritation.

  2. New Focuses on Surfactants for Personal Care Products

    Institute of Scientific and Technical Information of China (English)

    Wang Yan

    2007-01-01

    @@ Global output of surfactants is already more than 12 million tons a year today. There are more than 10 000 varieties in the portfolio. The total market sales value is over US$10 billion. The output of surfactants in China is more than 1.5 million tons a year in recent years. China can manufacture more than 3 380 varieties.

  3. 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

  4. NUMERICAL SIMULATION AND FIELD IMPLEMENTATION OF SURFACTANT FLOODING

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the features of surfactant flooding, a mathematical model for surfactant flooding is established. The adsorption-retention, convection diffusion of surfactant and influence of concentration change upon relative permeability curve are included in the model. The novel description of adsorption quantity of surfactant and relative permeability curve are presented, which enhance the coincidence between mathematical model and field practice, the relative errors of main development indexes are within 6%. The model is applied to the numerical research of the surfactant flooding in the untabulated beds of Xing1-3 surfactant flooding pilot site of No.4 Oil Production Company of Daqing Oilfield, the influences of surfactant concentration, injection quantity, slug combination mode upon the development effect and economic benefit are quantitatively analyzed, the injection scheme is optimized as follows: surfactant concentration is 0.5%, slug volume is 0.02 PV, slug combination mode is 2 slugs. After the implementation of scheme in oilfield, the cumulative increase of oil is 2186.0 t, up to nearly 30%.

  5. 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...

  6. 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.

  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. Polymeric surfactants for enhanced oil recovery : A review

    NARCIS (Netherlands)

    Raffa, Patrizio; Broekhuis, Antonius A.; Picchioni, Francesco

    2016-01-01

    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

  9. Battery charging system

    Energy Technology Data Exchange (ETDEWEB)

    Carollo, J.A.; Kalinsky, W.A.

    1984-02-21

    A battery charger utilizes three basic modes of operation that includes a maintenance mode, a rapid charge mode and time controlled limited charging mode. The device utilizes feedback from the battery being charged of voltage, current and temperature to determine the mode of operation and the time period during which the battery is being charged.

  10. Hydrophilic interaction liquid chromatography-tandem mass spectrometry quantitative method for the cellular analysis of varying structures of gemini surfactants designed as nanomaterial drug carriers.

    Science.gov (United States)

    Donkuru, McDonald; Michel, Deborah; Awad, Hanan; Katselis, George; El-Aneed, Anas

    2016-05-13

    Diquaternary gemini surfactants have successfully been used to form lipid-based nanoparticles that are able to compact, protect, and deliver genetic materials into cells. However, what happens to the gemini surfactants after they have released their therapeutic cargo is unknown. Such knowledge is critical to assess the quality, safety, and efficacy of gemini surfactant nanoparticles. We have developed a simple and rapid liquid chromatography electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method for the quantitative determination of various structures of gemini surfactants in cells. Hydrophilic interaction liquid chromatography (HILIC) was employed allowing for a short simple isocratic run of only 4min. The lower limit of detection (LLOD) was 3ng/mL. The method was valid to 18 structures of gemini surfactants belonging to two different structural families. A full method validation was performed for two lead compounds according to USFDA guidelines. The HILIC-MS/MS method was compatible with the physicochemical properties of gemini surfactants that bear a permanent positive charge with both hydrophilic and hydrophobic elements within their molecular structure. In addition, an effective liquid-liquid extraction method (98% recovery) was employed surpassing previously used extraction methods. The analysis of nanoparticle-treated cells showed an initial rise in the analyte intracellular concentration followed by a maximum and a somewhat more gradual decrease of the intracellular concentration. The observed intracellular depletion of the gemini surfactants may be attributable to their bio-transformation into metabolites and exocytosis from the host cells. Obtained cellular data showed a pattern that grants additional investigations, evaluating metabolite formation and assessing the subcellular distribution of tested compounds.

  11. Tensiometry and dilational rheology of mixed β-lactoglobulin/ionic surfactant adsorption layers at water/air and water/hexane interfaces.

    Science.gov (United States)

    Dan, Abhijit; Gochev, Georgi; Miller, Reinhard

    2015-07-01

    Oscillating drop tensiometry was applied to study adsorbed interfacial layers at water/air and water/hexane interfaces formed from mixed solutions of β-lactoglobulin (BLG, 1 μM in 10 mM buffer, pH 7 - negative net charge) and the anionic surfactant SDS or the cationic DoTAB. The interfacial pressure Π and the dilational viscoelasticity modulus |E| of the mixed layers were measured for mixtures of varying surfactant concentrations. The double capillary technique was employed which enables exchange of the protein solution in the drop bulk by surfactant solution (sequential adsorption) or by pure buffer (washing out). The first protocol allows probing the influence of the surfactant on a pre-adsorbed protein layer thus studying the protein/surfactant interactions at the interface. The second protocol gives access to the residual values of Π and |E| measured after the washing out procedure thus bringing information about the process of protein desorption. The DoTAB/BLG complexes exhibit higher surface activity and higher resistance to desorption in comparison with those for the SDS/BLG complexes due to hydrophobization via electrostatic binding of surfactant molecules. The neutral DoTAB/BLG complexes achieve maximum elastic response of the mixed layer. Mixed BLG/surfactant layers at the water/oil interface are found to reach higher surface pressure and lower maximum dilational elasticity than those at the water/air surface. The sequential adsorption mode experiments and the desorption study reveal that binding of DoTAB to pre-adsorbed BLG globules is somehow restricted at the water/air surface in comparison with the case of complex formation in the solution bulk and subsequently adsorbed at the water/air surface. Maximum elasticity is achieved with washed out layers obtained after simultaneous adsorption, i.e. isolation of the most surface active DoTAB/BLG complex. These specific effects are much less pronounced at the W/H interface.

  12. Charged Galileon black holes

    Science.gov (United States)

    Babichev, Eugeny; Charmousis, Christos; Hassaine, Mokhtar

    2015-05-01

    We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematically compatible with the field equations. This opens up the possibility for novel searches of hairy black holes in a far more general setting of Horndeski theory.

  13. Charged Galileon black holes

    CERN Document Server

    Babichev, Eugeny; Hassaine, Mokhtar

    2015-01-01

    We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematic...

  14. Aqueous foam surfactants for geothermal drilling fluids: 1. Screening

    Energy Technology Data Exchange (ETDEWEB)

    Rand, P.B.

    1980-01-01

    Aqueous foam is a promising drilling fluid for geothermal wells because it will minimize damage to the producing formation and would eliminate the erosion problems of air drilling. Successful use of aqueous foam will require a high foaming surfactant which will: (1) be chemically stable in the harsh thermal and chemical environment, and (2) form stable foams at high temperatures and pressures. The procedures developed to generate and test aqueous foams and the effects of a 260/sup 0/C temperature cycle on aqueous surfactant solutions are presented. More than fifty selected surfactants were evaluated with representatives from the amphoteric, anionic, cationic, and nonionic classes included. Most surfactants were severely degraded by this temperature cycle; however, some showed excellent retention of their properties. The most promising surfactant types were the alkyl and alkyl aryl sulfonates and the ethoxylated nonionics.

  15. 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.

  16. Fate and effects of amphoteric surfactants in the aquatic environment.

    Science.gov (United States)

    Garcia, M Teresa; Campos, Encarna; Marsal, Agustí; Ribosa, Isabel

    2008-10-01

    Amphoteric surfactants form part of specialty surfactants available for formulators to improve or design new formulations in response to environmental, toxicity, safety and performance demands. Nevertheless, limited information on the ecological properties of amphoterics is available. In the present work, the aerobic and anaerobic biodegradability and the aquatic toxicity of different types of amphoteric surfactants (three alkyl betaines, one alkylamido betaine and three alkyl imidazoline derivatives) were studied. The amphoteric surfactants tested were readily biodegradable under aerobic conditions (CO2 headspace test) and alkylamido betaines and alkyl imidazoline derivatives were also easily biodegradable under anaerobic conditions (test based on the ECETOC method). Toxicity to Photobacterium phosphoreum and Daphnia magna increased with the fatty chain length of the surfactant. The EC50 toxicity values of the amphoterics tested were higher than 5 mg/L, and alkyl imidazoline derivatives, with EC50 values from 20 to > 200 mg/L, showed the lowest aquatic toxicity.

  17. Enhanced solubilization of curcumin in mixed surfactant vesicles.

    Science.gov (United States)

    Kumar, Arun; Kaur, Gurpreet; Kansal, S K; Chaudhary, Ganga Ram; Mehta, S K

    2016-05-15

    Self-assemblies of equimolar double and single chain mixed ionic surfactants, with increasing numbers of carbon atoms of double chain surfactant, were analyzed on the basis of fluorescence and conductivity results. Attempts were also made to enhance the solubilization of curcumin in aqueous equimolar mixed surfactant systems. Mixed surfactant assembly was successful in retarding the degradation of curcumin in alkaline media (only 25-28 40% degraded in 10h at pH 13). Fluorescence spectroscopy and fluorescence quenching methods were employed to predict the binding position and mechanism of curcumin with self-assemblies. Results indicate that the interactions take place according to both dynamic and static quenching mechanisms and curcumin was distributed in a palisade layer of mixed aggregates. Antioxidant activity (using DPPH radical) and biocompatibility (using calf-thymus DNA) of curcumin-loaded mixed surfactant formulations were also evaluated. The prepared systems improved the stability, solubility and antioxidant activity of curcumin and additionally are biocompatible.

  18. Factors Affecting Surfactant Responsiveness: Influence of mode of administration and ventilation, disease stage and type of surfactant

    NARCIS (Netherlands)

    D.A.M.P.J. Gommers (Diederik)

    1998-01-01

    textabstractHistorically, Kurt von Neergaard was the first to suggest that surface tension plays an important role in lung elasticity. He showed, in 1929, that the pressure necessary for fIlling the lung with liquid was less than half the pressure necessary for filling the lung WiOl air, and conclud

  19. Novel serine-based gemini surfactants as chemical permeation enhancers of local anesthetics: A comprehensive study on structure-activity relationships, molecular dynamics and dermal delivery.

    Science.gov (United States)

    Teixeira, Raquel S; Cova, Tânia F G G; Silva, Sérgio M C; Oliveira, Rita; do Vale, M Luísa C; Marques, Eduardo F; Pais, Alberto A C C; Veiga, Francisco J B

    2015-06-01

    This work aims at studying the efficacy of a series of novel biocompatible, serine-based surfactants as chemical permeation enhancers for two different local anesthetics, tetracaine and ropivacaine, combining an experimental and computational approach. The surfactants consist of gemini molecules structurally related, but with variations in headgroup charge (nonionic vs. cationic) and in the hydrocarbon chain lengths (main and spacer chains). In vitro permeation and molecular dynamics studies combined with cytotoxicity profiles were performed to investigate the permeation of both drugs, probe skin integrity, and rationalize the interactions at molecular level. Results show that these enhancers do not have significant deleterious effects on the skin structure and do not cause relevant changes on cell viability. Permeation across the skin is clearly improved using some of the selected serine-based gemini surfactants, namely the cationic ones with long alkyl chains and shorter spacer. This is noteworthy in the case of ropivacaine hydrochloride, which is not easily administered through the stratum corneum. Molecular dynamics results provide a mechanistic view of the surfactant action on lipid membranes that essentially corroborate the experimental observations. Overall, this study suggests the viability of these serine-based surfactants as suitable and promising delivery agents in pharmaceutical formulations.

  20. Heat-regulated foaming in surfactant solutions

    Energy Technology Data Exchange (ETDEWEB)

    Pletnev, M.Y.; Eremina, L.D.; Vlasenko, I.G.

    1984-01-01

    This article examines the mechanism of the foam-inhibiting action resulting from the use of propylene oxide derivatives in solutions both of anionic and of nonionic surfactants. The objective is the creation of a detergent composition with heat-regulated foaming, which would foam well at 30-50/sup 0/ and poorly at 80-90/sup 0/, which is the usual temperature of washing machines. It is demonstrated that foaming can be regulated by the variation of the cloud points of solutions with the aid of additions of polypropylene glycols and their alkyl derivatives or block copolymers in solutions of surfactants. Foaming and foam stability decrease sharply above the cloud points of the solutions due to the foam-inhibiting action of the coacervate phase on the coexisting foam-forming solution. The foam inhibition of polypropylene glycols increases and becomes apparent at lower concentrations with the increase of the average molecular weight of the hydrophobic blocks, the increase of their relative content (in block copolymers with oxyethylene groups), and upon the introduction of alkyl groups.

  1. 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)

  2. Role of lung surfactant in respiratory disease: current knowledge in large animal medicine.

    Science.gov (United States)

    Christmann, U; Buechner-Maxwell, V A; Witonsky, S G; Hite, R D

    2009-01-01

    Lung surfactant is produced by type II alveolar cells as a mixture of phospholipids, surfactant proteins, and neutral lipids. Surfactant lowers alveolar surface tension and is crucial for the prevention of alveolar collapse. In addition, surfactant contributes to smaller airway patency and improves mucociliary clearance. Surfactant-specific proteins are part of the innate immune defense mechanisms of the lung. Lung surfactant alterations have been described in a number of respiratory diseases. Surfactant deficiency (quantitative deficit of surfactant) in premature animals causes neonatal respiratory distress syndrome. Surfactant dysfunction (qualitative changes in surfactant) has been implicated in the pathophysiology of acute respiratory distress syndrome and asthma. Analysis of surfactant from amniotic fluid allows assessment of fetal lung maturity (FLM) in the human fetus and exogenous surfactant replacement therapy is part of the standard care in premature human infants. In contrast to human medicine, use and success of FLM testing or surfactant replacement therapy remain limited in veterinary medicine. Lung surfactant has been studied in large animal models of human disease. However, only a few reports exist on lung surfactant alterations in naturally occurring respiratory disease in large animals. This article gives a general review on the role of lung surfactant in respiratory disease followed by an overview of our current knowledge on surfactant in large animal veterinary medicine.

  3. Dynamics of surfactant sorption at the air/water interface: continuous-flow tensiometry.

    Science.gov (United States)

    Svitova, T F; Wetherbee, M J; Radke, C J

    2003-05-01

    Dynamic interfacial tensiometry, gauged by axisymmetric drop shape analysis of static drops or bubbles, provides useful information on surfactant adsorption kinetics. However, the traditional pendant-drop methodology is not readily amenable to the study of desorption kinetics. Thus, the question of sorption reversibility is difficult to assess by this technique. We extend classical pendant/sessile drop dynamic tensiometry by immersing a sessile bubble in a continuously mixed optical cell. Ideal-mixed conditions are established by stirring and by constant flow through the cell. Aqueous surface-active-agent solutions are either supplied to the cell (loading) or removed from the cell by flushing with water (washout), thereby allowing study of both adsorption and desorption kinetics. Well-mixed conditions and elimination of any mass transfer resistance permit direct identification of sorption kinetic barriers to and from the external aqueous phase with time constants longer than the optical-cell residence time. The monodisperse nonionic surfactant ethoxy dodecyl alcohol (C(12)E(5)), along with cationic cetyltrimethyl ammonium bromide (CTAB) in the presence of added salt, adsorbs and desorbs instantaneously at the air/water interface. In these cases, the experimentally observed dynamic-tension curves follow the local-equilibrium model precisely for both loading and washout. Accordingly, these surfactants below their critical micelle concentrations (CMC) exhibit no detectable sorption-activation barriers on time scales of order a min. However, the sorption dynamics of dilute CTAB in the absence of electrolyte is markedly different from that in the presence of KBr. Here CTAB desorption occurs at local equilibrium, but the adsorption rate is kinetically limited, most likely due to an electrostatic barrier arising as the charged surfactant accumulates at the interface. The commercial, polydisperse nonionic surfactant ethoxy nonylphenol (NP9) loads in good agreement with

  4. 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

    1996-01-01

    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

  5. Interaction of a food-grade cationic surfactant (lauric arginate) with food-grade biopolymers (pectin, carrageenan, xanthan, alginate, dextran, and chitosan).

    Science.gov (United States)

    Bonnaud, Marieange; Weiss, Jochen; McClements, David J

    2010-09-08

    Lauric arginate (LAE) is a food-grade cationic surfactant that is a highly potent antimicrobial active against a wide range of food pathogens and spoilage organisms. In compositionally complex environments, the antimicrobial activity of cationic LAE is likely to be impacted by its interactions with other charged components. The purpose of this study was to characterize the interactions between cationic LAE and various food grade biopolymers with different charge characteristics: anionic (pectin, alginate, carrageenan, xanthan), neutral (dextran), and cationic (chitosan). Isothermal titration calorimetry (ITC) and turbidity measurements were used to characterize surfactant-biopolymer interactions and the solubility of any aggregates formed. ITC and turbidity measurements suggested that no complex formation occurred between the cationic LAE and the cationic or neutral biopolymers, although the critical micelle concentration (cmc) of the surfactant was changed because of excluded volume effects. On the other hand, ITC measurements indicated a strong binding interaction between cationic LAE and anionic biopolymers. The amount of surfactant bound and the solubility of the aggregates formed depended strongly on biopolymer type. The results of this study have important implications for the application of LAE in compositionally complex systems.

  6. The binding and insertion of imidazolium-based ionic surfactants into lipid bilayers: the effects of the surfactant size and salt concentration.

    Science.gov (United States)

    Lee, Hwankyu; Jeon, Tae-Joon

    2015-02-28

    Imidazolium-based ionic surfactants with hydrocarbon tails of different sizes were simulated with lipid bilayers at different salt concentrations. Starting with the random position of ionic surfactants outside the bilayer, surfactants with long tails mostly insert into the bilayer, while those with short tails show the insertion of fewer surfactant molecules, indicating the effect of the tail length. In particular, surfactants with a tail of two or four hydrocarbons insert and reversibly detach from the bilayer, while the inserted longer surfactants cannot be reversibly detached because of the strong hydrophobic interaction with lipid tails, in quantitative agreement with experiments. Longer surfactants insert more deeply and irreversibly into the bilayer and thus increase lateral diffusivities of the bilayer, indicating that longer surfactants more significantly disorder lipid bilayers, which also agrees with experiments regarding the effect of the tail length of ionic surfactants on membrane permeability and toxicity. Addition of NaCl ions weakens the electrostatic interactions between headgroups of surfactants and lipids, leading to the binding of fewer surfactants into the bilayer. In particular, our simulation findings indicate that insertion of ionic surfactants can be initiated by either the hydrophobic interaction between tails of surfactants and lipids or the electrostatic binding between imidazolium heads and lipid heads, and the strength of hydrophobic and electrostatic interactions depends on the tail length of surfactants.

  7. Problems in point charge electrodynamics

    CERN Document Server

    Ferris, Michael R

    2013-01-01

    (Shortened due to character limit) This thesis consists of two parts. In part I we consider a discrepancy in the derivation of the electromagnetic self force for a point charge. In the point charge framework the self force can be defined as an integral of the Lienard-Wiechert stress 3-forms over a suitably defined worldtube. We show the Schott term may be obtained using a null displacement vector to define the worldtube providing certain conditions are realized. Part II comprises an investigation into a problem in accelerator physics. In a high energy accelerator the cross-section of the beampipe is not continuous and there exist geometric discontinuities such as collimators and cavities. When a relativistic bunch of particles passes such a discontinuity the field generated by a leading charge can interact with the wall and consequently affect the motion of trailing charges. The fields acting on the trailing charges are known as (geometric) wakefields. We model a bunch of particles as a one dimensional contin...

  8. Effect of added surfactant on interfacial tension and spontaneous emulsification in alkali/acidic oil systems

    Energy Technology Data Exchange (ETDEWEB)

    Rudin, J.; Bernard, C.; Wasan, D.T. (Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering)

    1994-05-01

    An experimental investigation of the buffered surfactant-enhanced alkaline flooding system chemistry was undertaken to determine the influence of various species present on interfacial tension as a function of pH and ionic strength. Phase behavior tests that monitor the extent of emulsification are sufficient to determine the region of low interfacial tension. Optimization of interfacial tension by adjustment of the ionic strength alone may not necessarily provide the lowest interfacial tension under the best conditions. The pH should be simultaneously optimized along with ionic strength to allow better control over attainment of low interfacial tension. The dominant mechanism by which added surfactant aids in the reduction of interfacial tension is the formation of mixed micelles with the ionized acid. Although added surfactant partitioning from the influence of the un-ionized acid and ionic strength will affect interfacial behavior, the formation of mixed micelles plays a dominant role. Middle-phase formation is possible with a low acid oil using a petroleum sulfonate at a proper pH and ionic strength.

  9. Research on Influence Factors of Surfactivity of Polyester Polyether Block Copolymer

    Institute of Scientific and Technical Information of China (English)

    WU Ming-hua; LIN He-ming

    2008-01-01

    Polyester polyether block copolymer (PPBC) was synthesized by ester-exchange and polycodensation reactions using dimethyl terephthalate (DMT), ethylene glycol (EG) and polyethylene glycol (PEG) as monomer. The effects of PEG molecular weight, mol ratio of DMT to PEG (nDMT/nPEG), temperature and time of polycondensation reaction and vacuum degree in the reaction system on the surface tension and critical micelle concentration (CMC) of PPBC aqueous solution were studied. It was found that both the molecular weight and the concentration of PEG can affect PPBC'S surface activity obviously, and the optimum synthesis condition of PPBC used as surfactant is as follows: PEG molecular weight is 1500, mol ratio of DMT to PEG is 3, temperature and time of polycondensation reaction is 260°C×1h, vacuum degree of condensation reaction is 0.03-0.05 MPa. It was proved by surface tension measurement of PPBC aqueous solution that the PPBC synthesized in this condition is a good surfactant with excellent surfactivity.

  10. Flow behaviour and transitions in surfactant-laden gas-liquid vertical flows

    Science.gov (United States)

    Zadrazil, Ivan; Chakraborty, Sourojeet; Matar, Omar; Markides, Christos

    2016-11-01

    The aim of this work is to elucidate the effect of surfactant additives on vertical gas-liquid counter-current pipe flows. Two experimental campaigns were undertaken, one with water and one with a light oil (Exxsol D80) as the liquid phase; in both cases air was used as the gaseous phase. Suitable surfactants were added to the liquid phase up to the critical micelle concentration (CMC); measurements in the absence of additives were also taken, for benchmarking. The experiments were performed in a 32-mm bore and 5-m long vertical pipe, over a range of superficial velocities (liquid: 1 to 7 m/s, gas: 1 to 44 m/s). High-speed axial- and side-view imaging was performed at different lengths along the pipe, together with pressure drop measurements. Flow regime maps were then obtained describing the observed flow behaviour and related phenomena, i.e., downwards/upwards annular flow, flooding, bridging, gas/liquid entrainment, oscillatory film flow, standing waves, climbing films, churn flow and dryout. Comparisons of the air-water and oil-water results will be presented and discussed, along with the role of the surfactants in affecting overall and detailed flow behaviour and transitions; in particular, a possible mechanism underlying the phenomenon of flooding will be presented. EPSRC UK Programme Grant EP/K003976/1.

  11. Wetting Resistance of Commercial Membrane Distillation Membranes in Waste Streams Containing Surfactants and Oil

    Directory of Open Access Journals (Sweden)

    Lies Eykens

    2017-01-01

    Full Text Available Water management is becoming increasingly challenging and several technologies, including membrane distillation (MD are emerging. This technology is less affected by salinity compared to reverse osmosis and is able to treat brines up to saturation. The focus of MD research recently shifted from seawater desalination to industrial applications out of the scope of reverse osmosis. In many of these applications, surfactants or oil traces are present in the feed stream, lowering the surface tension and increasing the risk for membrane wetting. In this study, the technological boundaries of MD in the presence of surfactants are investigated using surface tension, contact angle and liquid entry pressure measurements together with lab-scale MD experiments to predict the wetting resistance of different membranes. Synthetic NaCl solutions mixed with sodium dodecyl sulfate (SDS were used as feed solution. The limiting surfactant concentration was found to be dependent on the surface chemistry of the membrane, and increased with increasing hydrophobicity and oleophobicity. Additionally, a hexadecane/SDS emulsion was prepared with a composition simulating produced water, a waste stream in the oil and gas sector. When hexadecane is present in the emulsion, oleophobic membranes are able to resist wetting, whereas polytetrafluoretheen (PTFE is gradually wetted by the feed liquid.

  12. Magnetic charge quantisation and fractionally charged quarks

    NARCIS (Netherlands)

    Hooft, G. 't

    1976-01-01

    If magnetic monopoles with Schwinger's value of the magnetic charge would exist then that would pose serious restrictions on theories with fractionally charged quarks, even if they are confined. Weak and electromagnetic interactions must be unified with color, leading to a Weinberg angle w close to

  13. Characterization of Phase and Emulsion Behavior, Surfactant Retention, and Oil Recovery for Novel Alcohol Ethoxycarboxylate Surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Moeti, Lebone T.; Sampath, Ramanathan

    2002-03-13

    Electrical conductivity measurements for middle, bottom, and top phases, as well as bottom/middle, and middle/bottom conjugate pair phases of the NEODOX 23-4/dodecane/10mM water system were continued from the previous reporting period. Electrical conductivity of the mixture decreased as the fraction of volume of the middle phase was increased and vice versa. Also inversion phenomena was observed. Following this, more emulsion studies at various temperatures were progresses. A theoretical model to predict the conductivity measurements using Maxwell equations was developed and sensitivity analyses to test the performance of the model was completed. Surtek, Golden, CO, our industrial partner in this project, investigated the suitability of the surfactant for enhanced oil recovery employing coreflooding techniques and observed lower surfactant and hydrocarbon recovery for NEODOX 23-4.

  14. Surfactant and nonlinear drop dynamics in microgravity

    Science.gov (United States)

    Jankovsky, Joseph Charles

    2000-11-01

    Large amplitude drop dynamics in microgravity were conducted during the second United States Microgravity Laboratory mission carried onboard the Space Shuttle Columbia (20 October-5 November 1995). Centimeter- sized drops were statically deformed by acoustic radiation pressure and released to oscillate freely about a spherical equilibrium. Initial aspect ratios of up to 2.0 were achieved. Experiments using pure water and varying aqueous concentrations of Triton-X 100 and bovine serum albumin (BSA) were performed. The axisymmetric drop shape oscillations were fit using the degenerate spherical shape modes. The frequency and decay values of the fundamental quadrupole and fourth order shape mode were analyzed. Several large amplitude nonlinear oscillation dynamics were observed. Shape entrainment of the higher modes by the fundamental quadrupole mode occurred. Amplitude- dependent effects were observed. The nonlinear frequency shift, where the oscillation frequency is found to decrease with larger amplitudes, was largely unaffected by the presence of surfactants. The percentage of time spent in the prolate shape over one oscillation cycle was found to increase with oscillation amplitude. This prolate shape bias was also unaffected by the addition of surfactants. These amplitude-dependent effects indicate that the nonlinearities are a function of the bulk properties and not the surface properties. BSA was found to greatly enhance the surface viscoelastic properties by increasing the total damping of the oscillation, while Triton had only a small influence on damping. The surface concentration of BSA was found to be diffusion-controlled over the time of the experiments, while the Triton diffusion rate was very rapid. Using the experimental frequency and decay values, the suface viscoelastic properties of surface dilatational viscosity ( ks ) and surface shear viscosity ( ms ) were found for varying surfactant concentrations using the transcendental equation of Lu

  15. Preparation and evaluation of sulphonamide nonionic surfactants

    Directory of Open Access Journals (Sweden)

    Ahmed, M. H. M.

    2010-03-01

    Full Text Available Alkyl (octyl, decyl and dodecyl; C8,C10 and C12 benzene sulphonyl chloride was used in the preparation of a novel series of nonionic surfactants (IV-VIa-c, (VII-IX a-c and (X-XIIa-c. The preparations were completed by reacting each alkyl (C8,C10 and C12 benzene sulphonyl chloride with ethanolamine to give (I-III respectively. The resulting products were reacted separately with ethylene oxide in the presence of different (base KOH, Lewis acid SnCl4 and k10 clay catalysts to produce different moles of nonionic surfactants (5, 7 and 9 in sequence corresponding to (IV-VIa-c, (VII-IX a-c and (X-XIIa-c respectively. The chemical structures of prepared nonionic surfactants were elucidated by IR and 1HNMR spectra. The surface activity, biodegradability and biological activities of the prepared compounds were investigated. The obtained data show that these compounds have good surface and biological activities as well as reasonable biodegradability properties.Cloruros de sulfonilbenceno alquilados (octil, decil, dodecil; C8, C10 y C12 fueron usados en la preparación de una nueva serie de surfactantes no iónicos (IV-VIa-c, (VII-IX a-c and (X-XIIa-c. Las preparaciones fueron completadas por reacción de cada cloruro de sulfonilbenceno alquilado (C8, C10 y C12 con etanolamina para dar los compuestos (IIII, respectivamente. Los anteriores productos reaccionaron separadamente con óxido de etileno en presencia de diferentes catalizadores (la base KOH, el ácido de Lewis SnCl4 y la arcilla k10 para producir secuencialmente diferentes surfactantes no iónicos con distintos moles de óxido de etileno (5, 7 y 9: (IV-VIa-c, (VII-IXa-c and (X-XIIa-c, respectivamente. La estructura química de los surfactantes no iónicos preparados fueron elucidadas mediante sus espectros de IR y 1H RMN. Las propiedades tensoactivas, biodegradabilidad y actividad biológica de los compuestos preparados fueron investigados. Los datos obtenidos muestran que estos compuestos tienen

  16. Effect of the Presence of Nonionic Surfactant Brij35 on the Mobility of Metribuzin in Soil

    Directory of Open Access Journals (Sweden)

    Eman M. ElSayed

    2013-04-01

    Full Text Available Given the water scarcity becoming endemic to a large portion of the globe, arid region irrigation has resorted to the use of treated, partially treated, or even untreated wastewaters. Such waters contain a number of pollutants, including surfactants. Applied to agricultural lands, these surfactants could affect the fate and transport of other chemicals in the soil, particularly pesticides. A field lysimeter study was undertaken to investigate the effect of nonionic surfactant, Brij35, on the in-soil fate and transport of a commonly used herbicide, metribuzin [4-amino-6-tert-butyl-3-(methylthio-1,2,4-triazin-5(4H-one]. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 mg m−3. Antibiotic-free cattle manure was applied (10 mg ha−1 at the surface of the lysimeters. Metribuzin was then applied to the soil surface of all lysimeters at a rate of 1.00 kg a.i. ha−1. Each of three aqueous Brij35 solutions, 0, 0.5 and 5 mg L−1 (i.e., “good”, “poor” and “very poor” quality irrigation water were each applied to the lysimeters in triplicate. Analysis for metribuzin residues in samples of both soil and leachate, collected over a 90-day period, showed the surfactant Brij35 to have increased the mobility of metribuzin in soil, indicating that continued use of poor quality water could influence pesticide transport in agricultural soils, and increase the risk of groundwater contamination.

  17. The effect of surfactant on pollutant biosorption of Trametes versicolor

    Science.gov (United States)

    Gül, Ülküye Dudu; Silah, Hülya; Akbaş, Halide; Has, Merve

    2016-04-01

    The major problem concerning industrial wastewater is treatment of dye and heavy metal containing effluents. Industrial effluents are also contained surfactants that are used as levelling, dispersing and wetting agents. The purpose of this study was to investigate the effect of surfactant on textile dye biosorption properties of a white rot fungus named Trametes versicolor. Reactive dyes are commonly used in textile industry because of their advantages such as brightness and excellent color fastness. A recative textile dye, called Everzol Black, was used in this study. The low-cost mollasses medium is used for fungal growth. The usage of mollases, the sugar refinery effluent as a source of energy and nutrients, gained importance because of reducing the cost and also reusing another waste. In biosorption process the effect of surfactant on dye removal properties of T. versicolor was examined as a function of pH, dye consentration and surfactant concentration. The results of this study showed that the surfactant enhanced the dye removal capacity of Trametes versicolor. The dye and surfactant molecules were interacted electrostatically and these electrostatic interactions improved dye removal properties of filamentous fungus T. versicolor. The results of this study recommended the use of surfactants as an inducer in textile wastewater treatment technologies.

  18. Surfactant aggregation and its application to drag reduction

    Energy Technology Data Exchange (ETDEWEB)

    Harwigsson, I.

    1995-09-01

    A number of different drag-reducing (DR) surfactants: nonionics, zwitterionics and ampholytics suitable for use in both cool and hot water solution are described. These surfactants have been tested under various conditions common in district energy distribution. The surfactants described are environmentally more acceptable than the organic salts of quaternary ammonium compounds which have so far dominated as DR surfactants. The micellar phase formed in water by the surfactant system cetylpyridinium chloride/sodium salicylate has been investigated with surfactant self-diffusion (NMR