Pulmonary Surfactant

Purpose To compare six commonly available silicates for their suitability to develop tablets by adsorbing components of liquid lipid-based drug delivery systems. Methods The tabletability of Aerosil® 200, Sipernat® 22, Sylysia® 350, Zeopharm® 600, Neusilin® US2 and Neusilin® UFL2 were studied by compressing each silicate into tablets in the presence of 20% microcrystalline cellulose and measuring the tensile strength of tablets produced. Three components of lipid based formulations, namely, Capmul® MCM EP (glycerol monocaprylocaprate), Captex® 355 EP/NF (caprylic/capric triglycerides) and Cremophor® EL (PEG-35 castor oil), were adsorbed individually onto the silicates at 1:1 w/w, and the mixtures were then compressed into tablets. The SEM photomicrographs of neat silicates and their 1:1 w/w mixtures (also 1:2 and 1:3 for Neusilin® US2 and Neusilin® UFL2) with one of the liquids (Cremophor® EL) were recorded. Results Neat Aerosil® 200, Sipernat® 22 and Sylysia® 350 were non-tabletable to the minimum acceptable tensile strength of 1 MPa, and they were also non-tabletable in presence of liquid. While Zeopharm® 600, Neusilin® US2 and Neusilin® UFL2 were tabletable without the addition of liquids, only Neusilin® US2 retained acceptable tabletability with 1:1 liquid. The SEM images of silicateliquid mixtures indicated that, except for Neusilin® US2, much of the adsorbed liquid distributed primarily at the surface of particles rather than inside pores, which hindered their compaction into tablets. Conclusion Among the six silicates studied, Neusilin® US2 was the only silicate able to produce tablets with acceptable tensile strength in presence of a lipid component at 1:1 w/w ratio due to the fact that the liquid was mostly adsorbed into the pores of the silicate rather than at the surface.

Using computer simulations, we investigate the interfacial structure of sodium dodecyl sulphate (SDS) monolayers adsorbed at the water surface and water–oil interfaces. Using an algorithm that removes the averaging effect of the capillary waves, we obtain a detailed view of the solvation structure of water around the monolayer. We investigate surface concentrations between 45 and 33 Å 2 per surfactant, which are near experimental conditions corresponding to the critical micellar concentration and the formation of Newton black films. The surfactants induce a layering structure in water, which disappears at approximately 1 nm from the monolayer plane. The water molecules exhibit a preferred orientation with the dipoles pointing towards the monolayer. The orientational order decays slowly, but it does not influence the hydrogen bond structure of water, which is significantly disrupted in the interfacial region only. These structural changes are qualitatively the same in SDS–water and o...

The orthogonal superimposition of flow and electric field in the filtration of particles or molecular aggregates in water can result in synergy to enhance permeate flux and rejection of solutes. The enhancements that are achieved in these systems can be far in excess of those encountered in other membrane techniques, particularly surfactant-based microfiltration. In this study a surfactant is added into a solution at a concentration above the critical micellar concentration (CMC) to form charged aggregates called micelles. Target metal ion with opposite charge is bound to the micelle. The solution is passed through two electrodes with a membrane placed on the porous rejecter electrode while the collector electrode is solid. The primary reason for the application of the electric field is to prevent membrane fouling which hampers filtration process. A cationic surfactant (dioctadecyldimethylammonium chloride) is used with chromium (chromium in the form of chromate) as the target metal...

Complex fluids composed of water, an organic solvent, and a surfactant have been recently employed as cleaning systems to remove hydrophobic materials, such as polymeric coatings, from solid surfaces. The simultaneous presence of surfactants and an organic solvent with good affinity for the polymer was proven necessary for the polymer's removal, but the comprehension of the cleaning mechanism is poorly understood. In this Article, we investigated the mechanism of removal, highlighting the specific role of each component in the interaction with the polymer film. In particular, the results from quartz crystal microbalance with dissipation monitoring (QCM-D) were compared with those obtained by using confocal microscopy to follow in situ the effect of a nanostructured fluid, i.e., a ternary formulation containing water, 2-butanone (MEK) as a good solvent for the polymer, and a nonionic surfactant (C9-11 ethoxylated alcohol, BR) on acrylic copolymer films (Paraloid B72). The results...

Temperature can have a significant effect on the conductivity and TDS (total dissolved solids) of water. In general, as the temperature of water increases, its conductivity also increases. This is because at higher temperatures, water molecules move more quickly and are able to carry more charged ions, which increases the overall conductivity. The effect of temperature on TDS is a bit more complex. TDS refers to the amount of dissolved solids in water, including minerals, salts, and other substances. As water temperature increases, the solubility of certain substances can change, which can impact the TDS measurement. For example, some salts become less soluble at higher temperatures, which can result in a decrease in TDS. However, other substances may become more soluble, which could increase the TDS measurement. i.e. it's important to take into account the effect of temperature when measuring conductivity and TDS in water to ensure accurate results.

Temperature can have a significant effect on the conductivity and TDS (total dissolved solids) of water. In general, as the temperature of water increases, its conductivity also increases. This is because at higher temperatures, water molecules move more quickly and are able to carry more charged ions, which increases the overall conductivity. The effect of temperature on TDS is a bit more complex. TDS refers to the amount of dissolved solids in water, including minerals, salts, and other substances. As water temperature increases, the solubility of certain substances can change, which can impact the TDS measurement. For example, some salts become less soluble at higher temperatures, which can result in a decrease in TDS. However, other substances may become more soluble, which could increase the TDS measurement. i.e. it's important to take into account the effect of temperature when measuring conductivity and TDS in water to ensure accurate results.

Surfactant-aided impregnation of MnSiF 6 into CNT fabrics followed by annealing at 400 °C forms CNT-MnF 2 composites. • Flexible CNT-MnF 2 cathodes retained a specific charge capacity of 388 mAh/g in half-cell after 100 cycles at 0.1 C. • MnF 2 loading affects largely the capacity of CNT-MnF 2 and MnF 2 loading between 70% and 80% gives highest specific capacity.

Aquatic macrophytes are important components of aquatic ecosystems, but these plants have become a problem due to their occurrence in different regions. Some studies aimed to demonstrate the effectiveness of herbicides to control these macrophytes; however, few studies report the possible ecotoxicological effects. The objective of this study was to estimate the acute toxicity (LC (I)50;96h) and assess water quality variables for glyphosate in the Rodeo ® formulation, Aterbane ® BR surfactant and mixtures of glyphosate + 0.5% and 1.0% of surfactant, for the guaru fish (Phallocerus caudimaculatus). The guaru was exposed to increasing concentrations of glyphosate and a mixture of glyphosate + 0.5 and 1.0% of surfactant. The mixture of glyphosate and glyphosate + 0.5 and 1.0% of surfactant showed (LC (I)50;96h) > 975.0 mg L -1 . For the surfactant, the rate was 5.81 mg L -1 . The glyphosate and mixtures of glyphosate + 0.5% and 1.0% of surfactant caused a decrease in pH and dissolved oxygen and increased the electrical conductivity of water. Glyphosate in the Rodeo ® formulation and the mixtures with surfactant Aterbane ® BR can be classified as practically nontoxic, whereas surfactant Aterbane ® BR can be considered as moderately toxic to guaru.

Herein, a theoretical model has been designed to study the aggregation behaviour of native bovine insulin using computational tools. Herein, self-association and aggregation of insulin in the presence of Gemini surfactant was investigated. The data showed the noteworthy interaction and stabilization of insulin due to the Gemini surfactants. Using Gemini surfactants having spacer of two carbons i.e., ethylene group, it was found that Gemini surfactant, 71 found to be best for the stabilization of insulin. This conclusion is based on the energy contributed due to hydrogen bonding, electrostatic interaction and Van der Waals interactions. Further, Gemini surfactant, 71 has been proven a better stabilizer when the results were compared with the reported ligands as in PDB files (1ZNI, 2HR7 and 2OLY). Further, its comparison was done with conventional surfactants. It was found that Gemini surfactant, 71 is more potent than the conventional surfactants.

Surfactant-based viscoelastic (SBVE) fluids are innovative nonpolymeric non-newtonian fluid compositions that have recently gained much attention from the oil industry. SBVE can replace traditional polymeric fracturing fluid composition by mitigating problems arising during and after hydraulic fracturing operations are performed. In this study, SBVE fluid systems which are entangled with worm-like micellar solutions of cationic surfactant: cetrimonium bromide or CTAB and counterion inorganic sodium nitrate salt are synthesized. The salt reagent concentration is optimized by comparing the rheological characteristics of different concentration fluids at 25 °C. The study aims to mitigate the primary issue concerning these SBVE fluids: significant drop in viscosity at high temperature and high shear rate (HTHS) conditions. Hence, the authors synthesized a modified viscoelastic fluid system using ZnO nanoparticle (NPs) additives with a hypothesis of getting fluids with improved rheology....

Surfactant-based viscoelastic (SBVE) fluids have recently gained interest from many oil industry researchers due to their polymer-like viscoelastic behaviour and ability to mitigate problems of polymeric fluids by replacing them during various operations. This study investigates an alternative SBVE fluid system for hydraulic fracturing with comparable rheological characteristics to conventional polymeric guar gum fluid. In this study, low and high surfactant concentration SBVE fluid and nanofluid systems were synthesized, optimized, and compared. Cetyltrimethylammonium bromide and counterion inorganic sodium nitrate salt, with and without 1 wt% ZnO nano-dispersion additives, were used; these are entangled wormlike micellar solutions of cationic surfactant. The fluids were divided into the categories of type 1, type 2, type 3, and type 4, and were optimized by comparing the rheological characteristics of different concentration fluids in each category at 25 °C. The authors have repor...

In this work, we use the Finite Differences Method and a well-reservoir (horizontal well) coupling technique based on the Peaceman equivalent radius calculation for the numerical simulation of natural gas production in shale gas formations. Due to the characteristics of shale gas reservoirs and the well-reservoir coupling model used, a numeric artifact (or numerical storage) appears in the initial instants of time. To attenuate the numerical artifact, we use mesh refinement near the horizontal well. Phenomena that favor the recovery of natural gas in shale reservoirs, such as gas slippage and adsorption, were also incorporated into the computational model. We performed sensitivity analysis studies which adequately capture the influence of these effects on the pressure behavior of the producing well. / Neste trabalho, emprega-se o Metodo das Diferencas Finitas e uma tecnica de acoplamento poco-reservatorio (poco horizontal) baseada no calculo do raio equivalente de Peaceman, para a s...

An important economical factor affecting Enhanced Oil Recovery (EOR) is the adsorption of surfactants on the rocks. Sacrificial agents may be used to reduce the adsorption of surfactants. An alkali (traditionally, sodium carbonate or sodium hydroxide) is often used as sacrificial adsorption agent; however, sodium carbonate is not an effective sacrificial agent in the presence of anhydrite in the rocks due to the reaction between sodium carbonate and sparingly-soluble anhydrite. Therefore, it is essential to develop a sacrificial adsorption agent that can act effectively in the presence of anhydrite. In this work, sodium polyacrylate is evaluated as a sacrificial agent, and is compared to many other conventional or recentlyrecommended sacrificial agents, and has shown advantage over all of them for the case of presence of anhydrite. Some experiments have been conducted to demonstrate the ineffectiveness of sodium carbonate as sacrificial agent in the presence of anhydrite. Effect of molecular weight of sodium polyacrylate is tested, and it is found that increase in molecular weight results in decrease in adsorption of surfactant until a certain molecular weight of polyacrylate is reached after which molecular weight has no further effect on reducing adsorption of surfactant. Addition of polyacrylate was shown to reduce adsorption of a selected anionic surfactant on different outcrop minerals, including Carlpool dolomite, industrial calcite, kaolinite, Berea sandstone, and Indiana limestone. To prove the point further, application of polyacrylate was tested with two different anionic surfactants. Adsorption of polyacrylate itself is measured in the presence and absence of surfactant and showed to be independent of the presence of surfactant. The effect of concentration of divalent ions and salinity in the brine on effectiveness of sodium polyacrylate as sacrificial agent has been evaluated on different minerals/rocks. Finally, dynamic adsorption data has been presented in different concentrations of sodium polyacrylate. All these experiments demonstrate the advantage of using sodium polyacrylate as sacrificial adsorption agent for anionic surfactants even in the presence of anhydrite in the rock.

Currently there exists a very high demand for electrochemical energy storage devices such as rechargeable cells and super capacitors due to massive increase in the use of portable electronics. At the moment this demand is mainly supplied by Li based cells. However, due to high cost, rapid reactivity and issues in disposal of Li, attention has been diverted on non Li based cells. Zn has been identified as a good candidate to replace Li. Even though several Zn based rechargeable cells were reported, not much work has been carried out on cells with conducting polymer cathode based Zn cells. In this study, performance of Zn rechargeable cells fabricated with conducting polymer polypyrrole (PPy) doped with a surfactant anion is reported. PPy films were galvanostatically electro polymerized on to stainless steel disc and cells were assembled with a polyvinylidenefluoride based gel polymer electrolyte having zinc-trifluoromethanesulfonate as the salt. Cells having different cathode thicknesses were fabricated and were characterized using cyclic voltammetry, electrochemical impedance spectroscopy and continuous charge-discharge tests. Cells exhibited open circuit voltages between 0.9 -1.0 V. Cycling testes showed that cycleable capacity almost follows the thickness variation of the cathode. Continuous charge-discharge tests revealed that the capacity decrease with the cycle number was higher in thinner films.

We describe the spontaneous self-assembly and the superstructure of a discrete surfactant-encapsulated cluster, (DODA) 40 (NH 4 ) 2 [(H 2 O) n ⊂Mo 132 O 372 (CH 3 COO) 30 (H 2 O) 72 ] (2, n ≈ 50), which consists of a hollow giant isopolyoxomolybdate core covered by a hydrophobic shell of dimethyldioctadecylammonium (DODA) cations. The structural characterization of these nanoporous core-shell particles is based on small-angle X-ray scattering (SAXS) data on solutions of the encapsulated clusters, TEM investigations, FT-IR and UV-vis spectroscopy, as well as determination of the molecular area of 2 by Langmuir film investigations. Computer modeling of the solvent-accessible surface of the encapsulated cluster yields a central cavity with a volume of 1.5 nm 3 that is occupied by approximately 50 H 2 O molecules. The cluster bears (Mo-O) 9-ring openings with an average diameter of 0.43 nm. The covered surface area of 84 Å 2 /DODA indicates a rather tight packing of the amphiphile at the cluster surface. Due to the unique supramolecular architecture of 2 as well as its high solubility in common organic solvents, this compound shows promising perspectives for future applications in host-guest chemistry and homogeneous size-selective catalysis.

Poly(vinyl acetate-co-ethylene) latex dispersions are prepared and their films investigated with a focus on the effect of composition upon redispersion. Films of dispersions containing sufficient amounts of poly(vinyl alcohol) (PVA) can be redispersed in water. This property is lost in the presence of surfactant, a fact which suggests a procedure to control film formation. It is demonstrated that redispersion is due to a PVA-membrane which separates the particles. Loss of redispersibility in the presence of surfactant proceeds with the breakup of the membranes and a corresponding change of film properties. Experimental data is provided by light microscopy, mechanical testing, and TEM in conjunction with a staining method new to the field. The hypothesis is developed that interaction with surfactant leads to imperfect PVA-membranes that are no longer able to prevent latex polymer interdiffusion. Fluorescence correlation spectroscopy demonstrates the formation of surfactant micelles, as well as the simultaneous adsorption and aggregation of PVA onto the micelles. It is concluded that the competing surface of the surfactant micelles traps enough PVA to cause thinning and fragmentation of the membranes surrounding the particles, which enables interdiffusion of latex polymer. This effect can be used to convert the system from one forming a redispersible coating to one forming a nonredispersible (permanent) film.

Surfactant treatment has become the standard of care in premature infants with respiratory distress syndrome (RDS). Pulmonary hemorrhage, pulmonary edema, pneumonia, and atelectasis have been shown to liberate inflammatory mediators and plasma proteins, which damage type II pneumocytes and inactivate surfactant. These disease processes may, therefore, lead to a secondary surfactant inactivation or deficiency, which can be an unrecognized cause of respiratory decompensation after initial recovery from RDS in this vulnerable population. This is a descriptive report of three cases, which had acute respiratory decompensation between 1 and 3 weeks of age. All three infants demonstrated a response to secondary doses of surfactant. We submit that the diagnosis and treatment of secondary surfactant deficiency in the critically ill premature neonate warrants further study.

Objective: To evaluate blood gases and ventilatory parameters before and after two doses of surfactant in premature infants with respiratory decompensation after recovery from primary respiratory distress syndrome (RDS). Study Design: This prospective pilot study enrolled infant's X500 g birth weight, from 7 days to 3 months of age, with a secondary respiratory decompensation lasting at least 4 h prior to study entry. Infants received two doses of surfactant, 12 h apart. Result: A total of 20 neonates qualified for secondary surfactant administration. PCO 2 (P<0.001); pH (P<0.001); mean airway pressure (P<0.05); FiO 2 (P<0.05); modified ventilatory indices (P<0.004) and respiratory severity scores (P<0.001) improved significantly at both 12 and 24 h after surfactant administration. Secondary surfactant administration may be effective in reducing short-term ventilatory requirements in neonates who have a respiratory decompensation after recovery from initial RDS. Randomized controlled trials are needed to confirm these preliminary findings.

The results of experimental study of the electrical and physical parameter of the gas discharge in air under the solutions of the two types of surfactants are given. The discharge was ignited between metal needle anode and liquid cathode. As the cathode the solutions of anionic surfactant C12H25SO4Na (SLS) and cationic surfactant C12H46ClN, (AOTC) were used. In the concentration range of 5·10-3-10 g/L and discharge current range of 20-100 mA the phenomenology of discharge was studied, the current densities and inputted power, cathode voltage drops, vibrational temperatures of N2(C3Πu), gas temperatures were obtained and reduced electric field strength was calculated. It was show that increase of the SLS concentration leads to the change in the discharge color due to transfer of Na atoms from liquid to the gas phase. In the same time there are no any new emission lines or band for the AOTC solutions were obtained. It was established that for cationic surfactants the cathode voltage d...

Solubility is essential factor for drug effectiveness, independent of the route of administration. Poorly soluble drug are formulated in industry. Nanosuspension technology can be used to improve the stability as well as bioavailability of poorly soluble drug. Nanosuspensions are also use in various dosage forms, including specialized drug delivery system such as mucoadhesive hydrogel. Nanosuspension have emerged as a promising strategy for the efficient delivery of hydrophobic drugs because of their versatile features and unique advantages. Recently, the engineering of nanosuspensions employing emulsions and micro-emulsions as templates has been addressed in the literature. The study is focused on the various method of preparation of nanosuspension with their advantages and disadvantages, formulation In vivo-in vitro evaluation method of nanosuspension and their application in drug delivery system.

The ethoxylated polysorbate, Tween, nonionic surfactants are extensively used as foam and emulsion stabilisers, 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 inter-micellar 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 twenty and less the effect is relatively small. The interaction increases with increasing ethoxylation, such that for a degree of ethoxylation of fifty the interac...

Nanoemulsions (NE) are isotropic, dispersions of oil, water, surfactant(s) and cosurfactant(s). A range of components (11 surfactants, nine cosurfactants, and five oils) were investigated as potential excipients for preparation of ketorolac tromethamine (KT) ocular nanoemulsion. Diol cosurfactants were investigated for the effect of their carbon chain length and dielectric constant (DEC), Log P, and HLB on saturation solubility of KT. Hen’s Egg Test—ChorioAllantoic Membrane (HET-CAM) assay was used to evaluate conjunctival irritation of selected excipients. Of the investigated surfactants, Tween 60 achieved the highest KT solubility (9.89 ± 0.17 mg/mL), followed by Cremophor RH 40 (9.00 ± 0.21 mg/mL); amongst cosurfactants of interest ethylene glycol yielded the highest KT solubility (36.84 ± 0.40 mg/mL), followed by propylene glycol (26.23 ± 0.82 mg/mL). The solubility of KT in cosurfactants was affected by four molecular descriptors: carbon chain length, DEC, log P and HLB. KT sol...

The effect of concentration and synergism on drug solubilising behaviour of PVP K 30 and PEG 6000 were investigated. Our results showed that amount of drug solubilised by the surfactants decreased as surfactant concentration was increased. Regarding the effect of synergism of the two surfactants on drug solubilisation our results failed to show synergism. The amount of drug solubilised by a single surfactant did not differ much when combination of surfactants were used.

The efficiency of sand filtration was investigated in terms of the behavior of the nanoplastics (NPLs) with different surface functionalities. The initial condition concentrations of NPLs were varied, and their effects on retention and transport were investigated under a constant flow rate in saturated porous media. The behavior of NPLs in this porous system was discussed by considering Z- average size and zeta (ζ) potential measurements of each effluent. The retention efficiencies of NPLs were ranked as functionalized with amidine [A-PS]+ &amp;gt; with sulfate [S-PS]− &amp;gt; with surfactant-coated amidine [SDS-A-PS]−. The reversibility of the adsorption process was revealed by introducing surfactant into the sand filter system containing adsorbed [A-PS]+ at three different initial state concentration conditions. The deposition behavior on sand grain showed that positively charged NPLs were attached to the quartz surface, and negatively charged NPLs were attached to the edge of the clay minerals, which can be caused by electrical heterogeneities. The homoaggregates made of positively charged NPLs were more compact than those made of negatively charged NPLs and surfactant-coated NPLs. An anti-correlation was revealed, suggesting a connection between the fractal dimension (Df) of NPL aggregates and retention efficiencies. Increased Df values are associated with decreased retention efficiencies.The findings underscore the crucial influence of NPL surface properties in terms of retention efficiency and reversible adsorption in the presence of surfactants in sand filtration systems

of the Thesis Presented in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (in Chemical Engineering) December, 2001 Pigment suspensions are important in several processes such as ceramics, paints, inks, and coatings. In the wet state, pigments are combined with a variety of chemical species such as polymers, surfactants, and polyelectrolytes which produce a complex colloidal system. The adsorption, desorption, and redistribution of these species at the pigment -aqueous solution interface can have an impact on the behavior in both the wet state or its final dried state. The goal of this work is to establish a molecular picture of the adsorption properties of these pigmented systems. A novel in situ infrared technique has been developed which allows the detection of adsorbed surface species on pigment particles in an aqueous environment. The technique involves the use of a polymeric binder to anchor the colloidal pigment particles to the surface of an internal reflection element (IRE). The binder only weakly perturbs about 25% of the reactive surface sites (hydroxyl groups) on silica. The reaction of succinic anhydride with an aminosilanized silica surface has been quantified using this technique. continuing guidance and support throughout both the author's M.S. and Ph.D. programs, along with leading a nationally recognized research program in the field of Paper Surface Science. A special thanks is due to Dr. Tripp for providing such a stimulating environment for advanced research, for devoting countless hours to pertinent discussions relating to this project, and also for being a compassionate friend as well as advisor. The author would also like to express a sincere thanks to Dr. Bill DeSisto, Dr. William Unertl, and Dr. Adriaan van Heiningen for the time which was devoted to help lead direction in this project, and for the time devoted to reading and commenting on this thesis.

Background: Enzymes have found extensive and growing application in the field of chemical organic synthesis and resolution of chiral intermediates. In order to stabilise the enzymes and to facilitate their recovery and recycle, they are frequently immobilised. However, immobilisation onto solid supports greatly reduces the volumetric and specific activity of the biocatalysts. An alternative is to form self-immobilised enzyme particles. Results: Through addition of protein cross-linking agents to a water-in-oil emulsion of an aqueous enzyme solution, structured self-immobilised spherical enzyme particles of Pseudomonas fluorescens lipase were formed. The particles could be recovered from the emulsion, and activity in aqueous and organic solvents was successfully demonstrated. Preliminary data indicates that the lipase tended to collect at the interface. The immobilised particles provide a number of advantages. The individual spherical particles had a diameter of between 0.5-10 µm, but tended to form aggregates with an average particle volume distribution of 100 µm. The size could be controlled through addition of surfactant and variations in protein concentration. The particles were robust enough to be recovered by centrifugation and filtration, and to be recycled for further reactions. They present lipase enzymes with the active sites selectively orientated towards the exterior of the particle. Co-immobilisation with other enzymes, or other proteins such as albumin, was also demonstrated. Moreover, higher activity for small ester molecules could be achieved by the immobilised enzyme particles than for free enzyme, presumably because the lipase conformation required for catalysis had been locked in place during immobilisation. The immobilised enzymes also demonstrated superior activity in organic solvent compared to the original free enzyme. This type of self-immobilised enzyme particle has been named spherezymes.

Respiratuvar Distres Sendromu (RDS) ve komplikasyonlarý yenidoðan bebeklerin en önemli mortalite ve morbidite nedenlerinden biridir. Geliþmiþ ülkelerde yenidoðan bebek ölümlerinin dörtte birinin RDSye baðlý olduðu bilinmektedir. Son yýllarda mekanik solunum cihazlarýnýn kullanýlmasý, destek tedavisindeki geliþmelerin yanýsýra ekzojen surfaktanýn kullanýlmasý RDSye baðlý mortaliteyi belirgin olarak azaltmýþtýr. Fujiwara ve arkadaþlarý tarafindan 1980 yýlýnda ilk kez kullanýlmasýný izleyen çok geniþ çalýþmalar yapýlmasýna raðmen doz, doz sayýsý, doz aralýðý, surfaktan tipi ve kullaným þekli hala tartýþýlmaktadýr. Sunumda surfaktanýn yapýsý, etki mekanizmasý ve klinik uygulamalara deðinilmiþ ve uygulamalar literatür ýþýðýnda tartýþýlmýþtýr.

A carbon paste electrode modified by alcian blue was used for detection of dopamine (DA). The modified electrode exhibited strong promoting effect and stability towards the electrochemical oxidation of dopamine at pH 6.6 in phosphate buffer solution (PBS). The effects of scan rate, concentration, pH, surfactants and modifier have been studied. Non-ionic surfactant Triton-X 100(TX-100) showed very good electrocatalytic effect on the modified carbon paste electrode. The detection limit of the modified carbon paste electrode is 1 x 10 -7 M for dopamine.

Fetal lung maturation is regulated by mesenchymal-epithelial cell communication, which plays a major role in the control of surfactant synthesis by alveolar type II cells. We have recently shown that keratinocyte growth factor (KGF), also called fibroblast growth factor-7, enhances the maturation of fetal alveolar epithelial type II cells. Here, we investigated, among the factors produced by lung mesenchyme, the part attributable to KGF in the control of surfactant synthesis. Using a KGF-neutralizing antibody, we assessed surfactant phospholipid synthesis by measuring choline incorporation into disaturated phosphatidylcholine of isolated fetal type II cells. We found that KGF accounts for about half of the stimulating activity present in fetal lung fibroblast-conditioned medium (FCM). By contrast, the use of an epidermal growth factor-neutralizing antibody did not alter the FCM-stimulating activity. To further delineate KGF properties as a mesenchymal mediator, we wondered about its possibility to relay glucocorticoid-stimulating activity on the synthesis of the phospholipid moiety of surfactant in fetal lung fibroblasts. A 24-h exposure to dexamethasone led us to detect a 50% increase in the level of KGF messenger RNA (mRNA) in isolated fetal lung fibroblasts. Moreover, anti-KGF antibody totally abolished the further increase of FCM-stimulating activity induced by dexamethasone. Thus, KGF seems to be a major player in mediating glucocorticoid stimulation of fetal lung maturation. (Endocrinology 142: 1814(Endocrinology 142: -1819(Endocrinology 142: , 2001) )

We briefly review recent developments concerning the use of carbon nanostructures in polymer composite thin films for write-once-read-many-times memory devices. We also show that carbon sphere/ poly(vinylphenol) composites prepared with the addition of hexadecyltrimethylammonium bromide as a surfactant show better carbon sphere dispersion, allowing in principle a memory device size reduction. Devices constructed with surfactant added carbon-sphere/poly(vinylphenol) composites allow writing the ON state in $200 ns and the write operation consumes 5 Â 10 À5 J cm À2 when a pulse with an amplitude of 5 V and a length of 1 ms is used.

We use complementary experiments-proton NMR diffusometry and relaxometry, deuterium NMR lineshapes, and rheometry-to construct a comprehensive picture of the microscopic structure of a mixed-surfactant wormlike micellar system composed of a zwitterionic surfactant and an anionic surfactant in brine. In this system, at some surfactant concentrations, the time for micellar breaking and recombination s b is not small compared with the micellar reptation time s R , weakening the condition to obtain a stress relaxation function with just one relaxation time at long times. From NMR relaxometry, we determine the overlap concentration. Deuterium NMR spectral lineshapes indicate the presence of a wide angular distribution in the orientational order. NMR diffusometry and rheology probe different timescales and yield complementary information indicating polymer-like behaviour at the corresponding lengthscales. Via NMR, surfactant diffusion coefficients are seen to decrease with increasing diffusion time, consistent with restricted diffusion within a reptating micelle. At the same time, comparison of measurements with protonated and deuterated surfactants strongly suggests that the measured short and long time diffusion coefficients correspond to intra-micellar and micellar diffusion, respectively. Fitting the diffusion results to a simple model, the average end-to-end micellar distance is estimated to be in the 1 mm range and only weakly dependent on concentration. The water diffusion measurements, on the other hand, imply a high degree of water structuring at the micellar surface. We also find that the wormlike micelles obeyed simple polymer-like scaling behaviors, with a crossover from Zimm-like (diffusion) to Rouse-like (rheology) exponents.

We use complementary experiments-proton NMR diffusometry and relaxometry, deuterium NMR lineshapes, and rheometry-to construct a comprehensive picture of the microscopic structure of a mixed-surfactant wormlike micellar system composed of a zwitterionic surfactant and an anionic surfactant in brine. In this system, at some surfactant concentrations, the time for micellar breaking and recombination s b is not small compared with the micellar reptation time s R , weakening the condition to obtain a stress relaxation function with just one relaxation time at long times. From NMR relaxometry, we determine the overlap concentration. Deuterium NMR spectral lineshapes indicate the presence of a wide angular distribution in the orientational order. NMR diffusometry and rheology probe different timescales and yield complementary information indicating polymer-like behaviour at the corresponding lengthscales. Via NMR, surfactant diffusion coefficients are seen to decrease with increasing diffusion time, consistent with restricted diffusion within a reptating micelle. At the same time, comparison of measurements with protonated and deuterated surfactants strongly suggests that the measured short and long time diffusion coefficients correspond to intra-micellar and micellar diffusion, respectively. Fitting the diffusion results to a simple model, the average end-to-end micellar distance is estimated to be in the 1 mm range and only weakly dependent on concentration. The water diffusion measurements, on the other hand, imply a high degree of water structuring at the micellar surface. We also find that the wormlike micelles obeyed simple polymer-like scaling behaviors, with a crossover from Zimm-like (diffusion) to Rouse-like (rheology) exponents.

The aim of this study was to prepare nanostructured lipid carriers (NLC)-based topical gel of aceclofenac for the treatment of inflammation and allied conditions. Stearic acid as the solid lipid, oleic acid as the liquid lipid, pluronic F68 as the surfactant, and phospholipon 90G as the co-surfactant were used. NLCs were prepared by melt-emulsification, low-temperature solidification, and high-speed homogenization methods. Characterization of the NLC dispersion was carried out through particle size analysis, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and an in vitro release study. The anti-inflammatory effect of the NLC gel was assessed by the rat paw edema technique and compared to marketed aceclofenac gel. The NLC dispersions exhibited d(90%) between 233 nm and 286 nm. All of the NLC showed high entrapment efficiency ranging from 67% to 82%. The particle size of NLC was further confirmed by the SEM study. The result of DSC showed that aceclofenac ...

Polyamide bio-nanocomposites were successfully prepared using a surfactant-free approach. The clay morphology was fixed by dispersing the ammonium ion-exchanged clay in acetic acid. This was mixed wi th an aceti c aci d sol uti on of the polyamide and the composite was recovered by precipitation with water. The composites featured a mixed morphology containing some exfoliated clay sheets together with nano-sized clay tactoids. Bio-nanocomposites containing as much as 27.5 wt.% clay were obtained. At this filler level, and depending on the temperature, the modulus was up to nine times higher than that of the parent polymer. Addition of clay also increased the glass transition temperature by as much as 5 °C. This indicates that the high interfacial surface area, presented by the clay platelets dispersed in the matrix, significantly impaired the polymer chain mobility.

Background Boswellic acid (BA), a phytoconstituent obtained from Boswellia serrata, suffers from several limitations after oral administration such as poor systemic absorption, high first-pass metabolism and high frequency of dose requirement, which creates a need to develop an alternative route for drug administration via novel drug delivery formulation. The present research work aims at developing ultradeformable vesicular carriers (transferosomes) for transdermal delivery of boswellic acid to effectively deliver the drug into deeper layers of the skin reaching the target site and thus improving its systemic bioavailability. Ultradeformable vesicles were prepared by thin-film hydration technique, and the formulation was optimized using 32 full factorial design where the amount of lecithin (mg) and concentration of surfactant (%) were considered as independent variables. The formulated boswellic acid-loaded vesicles were incorporated into transdermal film via solvent evaporation te...

The goal of this research is the development of a theoretical quantitative understanding of the dynamics of high Reynolds number free-surface flows under large free-surface deformations in the presence of one or multiple surfactants. The longterm goal of this research is to understand the effect of the surfactants on (1) turbulence, (2) waves, (3) slick formation and (4) mass transfer through the free surface.

Catanionic surfactant mixtures form a wide variety of organized assemblies and aggregates with improved physicochemical and biological properties. The green catanionic mixture C3(CA)2:lichenysin (molar ratio 8:2) showed antimicrobial synergies against Yersinia enterocolitica, Bacillus subtilis, Escherichia coli O157:H7 and Candida albicans. Flow cytometry and viability studies indicated that this catanionic mixture increases the probability of Y. enterocolitica (38.2%) and B. subtilis (17.1%) cells entering a viable but nonculturable state. Zeta potential showed that one of the cationic charges of C3(CA)2 is neutralised by lichenysin. An isotherm study demonstrated the formation of a stable aggregate between the two surfactants that was able to interact with bacterial phospholipids. The lowest hemolysis (22.1μM) was obtained with the catanionic mixture, although an irritant potential (0.70) was characterised. According to the therapeutic index, the C3(CA)2:lichenysin mixture was the...

Electrospinning of polymers typically requires high solution concentrations necessitated by the requirement of sufficient chain overlaps to achieve the required viscoelastic properties. Here, we report on a novel supramolecular approach, involving polymer/surfactant complexes, which allows for a significant reduction in the solution concentration of polymer for electrospinning. The approach involved supramolecular complexation of poly(4-vinylpyridine) (P4VP) with a surfactant, dodecylbenzenesulfonic acid (DBSA), via ionic interactions. The supramolecular complexation of P4VP with DBSA led to a significant increase in the solution viscosity even at a DBSA/4VP molar ratio as low as 0.05. Furthermore, the solution viscosity of the P4VP/DBSA complex increased significantly with the DBSA/4VP molar ratio. The increase in the viscosity for the P4VP/DBSA complexes was plausibly due to the formation of physical cross-links between P4VP chains driven by hydrophobic interactions between the surfactant tails. The formation of such physical cross-links led to a significant decrease in the solution concentration needed for the onset of semidilute entangled regime. Thus, the P4VP/DBSA complexes could be electrospun at a much lower concentration. The critical solution concentration to obtain bead-free uniform nanofibers of P4VP/DBSA complexes in dimethylformamide was reduced to 12% (w/v), which was not possible for neat P4VP solution even up to approximately 35% (w/v). Furthermore, small-angle X-ray scattering and polarized optical microscopy results revealed that the electrospun nanofibers of P4VP/DBSA complexes selfassembled in lamellar mesomorphic structures similar to that observed in bulk. However, the electrospun nanofibers exhibited significantly improved lamellar order, which was plausibly facilitated by the preferred orientation of P4VP chains along the fiber axis.

This paper proposes a phase-field model for the lattice Boltzmann method which has discretized symmetrical directions of velocities in a cartesian grid, to simulate the soluble surfactant in a Multicomponent multiphase system. Despite other existing phase-field models following Langmuir relation, the interfacial tension can be calculated analytically in this proposed model. Parameters playing roles in the models and controlling the surfactant’s strength and interaction with other phases are obtained directly from a given initial interfacial tension and bulk surfactant. Consequently, there is no further need for trial-and-error simulations, and a real system, e.g., oil-water-surfactant, can be simulated with given initial parameters. The model is validated with the analytical result for a planar oil–water-surfactant system. Furthermore, the method for reobtaining numerical interfacial tension for five different cases is tested and compared with the given initial values for an oil dro...

Les mousses liquides sont des empilements compacts de bulles de gaz dispersées dans une solution de tensioactifs. Elles ont de nombreuses applications industrielles, entre autres dans le domaine agro-alimentaire ou celui du traitement des eaux et des déchets. Dans notre présent travail de thèse, on cherche à réaliser des mousses avec des nouvelles microstructures en faisant varier les interactions entre les bulles, caractérisées par l'angle de contact. Cette idée, jusqu'ici peu exploitée, est suggérée par une analogie entre les bulles et les atomes dont l'empilement forme des solides de structures diverses, en fonctions des interactions atomiques. Nous avons montré expérimentalement et numériquement comment la structure d'une mousse liquide dépend non seulement de la fraction volumique et de la taille des bulles, mais en plus, de sa physico-chimie. En effet, l'ajout de sel à une solution de tensioactifs ioniques peut induire des interactions attractives entre les bulles qui modifient les angles de contact, les interstices (bords de Plateau et noeuds) et la perméabilité de la mousse.

A new method of cloud point extraction was determined for preconcentration and determination of different metal ions like copper(II), nickel(II) and cobalt(II) ions. The complexation has been done by bis(2-acetyl pyridine 4-phenyl 3-thiosemicarbazone) (APPT) using sodium dodecyl sulphate (SDS) as surfactant. Metal ions are extracted into the phase rich in SDS after centrifugation. Initially, micellar phase was dissolved in 10 mL of deionized water then acidified with 0.5 mol/L HNO3, enhanced the surfactantrich phase and analyzed by flame atomic absorption spectrometry (FAAS). The effects of pH, the concentrations of metal ions and chelating agent (APPT), volume of surfactant (SDS), equilibration temperature and time were studied on CPE. The preconcentration factor obtained was 25 and the limits of detection (DL) obtained for cobalt(II), nickel(II) and copper(II) were 1.5, 1.7 and 2.4 ng/mL, respectively. This method of preconcentration was effectively useful for the determination of cobalt(II), nickel(II) and copper(II) in water samples.

Biosurfactants are amphipathic molecules produced from microorganisms. There are relatively few species known where the detailed chemical characterization of biosurfactant has been reported. Here, we report isolation and chemical characterization of the biosurfactant produced by a biodesulfurizing bacterium Gordonia sp. IITR100. Biosurfactant production was determined by performing oil spreading, drop-collapse, Emulsion index (E24), and Bacterial adhesion to hydrocarbons (BATH) assay. The biosurfactant was identified as a glycolipid by LCMS and GCMS analysis. The chemical structure was further confirmed by performing FTIR and NMR of the extracted biosurfactant. The emulsion formed by the biosurfactant was found to be stable between temperatures of 4°C to 30°C, pH of 6 to 10 and salt concentrations up to 2%. It was successful in reducing the surface tension of the aqueous media from 61.06 mN/m to 36.82 mN/m. The biosurfactant produced can be used in petroleum, detergents, soaps, the ...

In the era of Methicillin-resistant Staphylococcus aureus (MRSA) resulting in the ineffectiveness of antibiotics is of keen interest to researchers in up-to-date scenarios. The current study aims to formulate water-soluble drug (Gemifloxacin) loaded nanocubosomes via melt dispersion emulsification method using glyceryl mono oleate/ poloxamer 407 in different ratios. Firstly, the optimized formula (F6) was evaluated for surface morphology, particle size, polydispersity index, zeta potential, drug entrapment efficiency%, compatibility studies, and in vitro release. Secondly, the optimized formulation of nanocubosomes was laden as in situ gel and evaluated for gelling effect, in vitro release, drug content, stability study, and antimicrobial activity. The optimized nanocubosomes F6 showed a particle size of less than 200 nm, a zeta potential-26.6 ± 1.3 mV, and a high entrapment efficiency of 96.62 ± 2.35%. The developed in situ gel (F6) shows prolonged drug release and good stability. Our objectives in that study are to investigate the effectiveness of that novel approach for the management of corneal lesions and inflammation in a rat model of MRSA keratitis as well as in vitro estimation for their MIC. Results showed greater potency by having lower MICs than Gemifloxacin solution and significant reductions in corneal opacity and inflammation score in rats treated with GEM-loaded nanocubosomes compared to those treated with Gemifloxacin solution. Histopathological analysis demonstrated a preservation of the normal corneal structure in the GEM-loaded nanocubosomes group. It is clear from the above-performed studies that the prepared in situ gel would afford a profitable treatment for keratitis with a lack of irritancy.

This contribution deals with the development of emulsions formulated using thyme essential oil and a new biomass-derived surfactant. In addition, this work extends our knowledge concerning the factors that can influence stability and droplet size distributions of microfluidized emulsions, such as the geometry of the rotor-stator used and the homogenization rate in the primary homogenization. Stable thyme oil-in-water emulsions (30 wt%) containing submicron droplets were formed. Interestingly, laser diffraction results reveal that mean droplet sizes are mainly controlled by homogenization rates and polydispersity by the rotor-stator geometry used in the first step of homogenization. In addition, higher droplet sizes for pre-emulsions seem to be a key factor in order to reduce both the degree of recoalescence and the size of the droplets in the second homogenization step. Furthermore, higher droplet sizes in the preemulsion favour higher physical stability of the final emulsions. Finally, this research highlights the importance of controlling primary homogenization conditions for the physical stability of microfluidized emulsions that contain natural ingredients.