Academic literature on the topic 'Surface active agents. Surface chemistry. Micelles'

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Journal articles on the topic "Surface active agents. Surface chemistry. Micelles"

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Akisada, Hideo, Junko Kuwahara, Minako Kunisaki, Keiko Nishikawa, Shiho Akagi, Mituyo Wada, Ayano Kuwata, and Sakiko Iwamoto. "A circular dichroism study of the interaction between n-decanoyl-N-methylglucamide and surface active agents in mixed micelles." Colloid and Polymer Science 283, no. 2 (April 27, 2004): 169–73. http://dx.doi.org/10.1007/s00396-004-1113-4.

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Abouzeid, Fatma M. "Study of Steel Electro-dissolution Behavior in Presence of Some Surfactants. Electrochemical Investigation and Surface Active Properties Determination." Revista de Chimie 72, no. 3 (July 29, 2021): 179–97. http://dx.doi.org/10.37358/rc.21.3.8447.

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Steel electro-dissolution performance was investigated in orthophosphoric acid in the presence of N-oleyl 1.3 diaminopropane, Benzalkounuim chloride, Soduim lauryl sulphate and Di-Isononyl phthalate as a surfactant using potentiodynamic polarization measurements. The retardation performance of these surfactants was examined. The surfactant surface active parameters were estimated based on surface tension measurements. The parameters calculated comprise the critical micelle concentration (CMC), maximum surface excess (Гmax), minimum surface area (Amin) and effectiveness (πCMC). The micellization thermodynamic parameters (ΔGmic, ΔSmic) for the estimated surfactants were also computed. Results obtained from surface active properties are comparable with those gained from galvanostatic polarization measurements. Temperature influence on the steel dissolution performance was examined at 25 to 40oC range. Steel kinetic study in orthophosphoric acid- free solution and orthophosphoric acid containing surfactant was also examined. The dissolution kinetic and activated parameters were computed. Results based on microscopy measurement indicate that, addition of new four surfactants, resulting in the solution shows potential, a discrete progress in the metal texture was monitored. Improvement produced in electro-polishing bath by the investigated SAS that owing to the adsorption of such surface active agents on the anode surface.
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Zakharova, L. Ya, S. B. Fedorov, L. A. Kudryavtseva, V. E. Bel'skii, and B. E. Ivanov. "Acid-base properties of bis(chloromethyl)phosphinic acid para-nitroanilide in aqueous micellar solutions of surface active agents." Bulletin of the Academy of Sciences of the USSR Division of Chemical Science 39, no. 5 (May 1990): 883–85. http://dx.doi.org/10.1007/bf00961674.

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Friberg, Stig E., Abeer Al Bawab, and Ahmad A. Abdoh. "Surface active inverse micelles." Colloid and Polymer Science 285, no. 14 (July 25, 2007): 1625–30. http://dx.doi.org/10.1007/s00396-007-1734-5.

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Eissa, A. M. F. "Amphoteric surface active agents." Grasas y Aceites 46, no. 4-5 (October 30, 1995): 240–44. http://dx.doi.org/10.3989/gya.1995.v46.i4-5.931.

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Pryce, A. "Surface active agents: some applications in surface coatings." Pigment & Resin Technology 16, no. 2 (February 1987): 15–21. http://dx.doi.org/10.1108/eb042329.

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Hornof, V., and R. Hombek. "Surface-active agents based on propoxylated lignosulfonate." Journal of Applied Polymer Science 41, no. 910 (1990): 2391–98. http://dx.doi.org/10.1002/app.1990.070410939.

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Akhir, Nur Asyraf Md, Ismail Mohd Saaid, Ahmad Kamal Idris, Anita Ramli, Nurul Amirah Ismail, and Afif Izwan Abd Hamid. "Dynamic Interfacial Tension Behavior of Pure and Binary Surfactant System." Journal of Computational and Theoretical Nanoscience 17, no. 2 (February 1, 2020): 1251–59. http://dx.doi.org/10.1166/jctn.2020.8797.

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Surfactants are very important surface-active agents in implementation of chemical enhanced oil recovery for oil-water interfacial tension and wettability alteration. However, the high adsorption of surfactant on reservoir rock reduces the efficiency of surfactant flooding. Conventionally, inorganic alkali has been introduced to reduce adsorption of surfactant, but alkali will lead to the formation of emulsion, formation damage and scaling. Therefore, lignosulfonate, a sacrificial agent has been introduced as an alternative to inorganic alkali. In this paper, the critical micelle concentration (CMC) and dynamic interfacial tension (IFT) behavior of a pure and binary system of internal olefin sulfonate (IOS) and lignosulfonate (LS) at brine-decane interfaces are determined by using a spinning drop method. The physicochemical properties of pure and binary of IOS and LS system are determined by conductivity and pH measurements. The CMC value of IOS in 3.5 wt% brine salinity is higher compared to LS due to the isomeric branched of IOS which can occupy a larger area per molecules. The dynamic interfacial tension of IOS shows the fast adsorption of surfactant molecules to the brine-decane interfaces. This is indicated by the fast equilibrium interfacial tension reached by IOS. In comparison, the LS pure system shows decreasing behavior of dynamic interfacial tension. The fast adsorption at the interfaces is only reached for higher LS concentrations. The synergy effect between IOS and LS system shows a reduction in the interfacial value with LS optimum concentration of 0.6 wt%. The drop in conductivity and pH values indicated the development of a tightly packed lamellar liquid crystalline structure. These physicochemical properties are in agreement with the dynamic interfacial tension behavior of the IOS and LS system. This study has demonstrated the significant impact of the LS addition in reducing the dynamic interfacial tension of the surfactant system.
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El-Dougdoug, W. I. A. "Synthesis and surface active properties of cationic surface active agents from crude rice bran oil." Grasas y Aceites 50, no. 5 (October 30, 1999): 385–91. http://dx.doi.org/10.3989/gya.1999.v50.i5.683.

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Bower, C. K., M. K. Bothwell, and J. McGuire. "Lantibiotics as surface active agents for biomedical applications." Colloids and Surfaces B: Biointerfaces 22, no. 4 (December 2001): 259–65. http://dx.doi.org/10.1016/s0927-7765(01)00199-0.

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Dissertations / Theses on the topic "Surface active agents. Surface chemistry. Micelles"

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Wang, Xueyun Sharon. "NMR relaxation study of the interaction of N-alkyl nicotinamides with micelles." Scholarly Commons, 1992. https://scholarlycommons.pacific.edu/uop_etds/2233.

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The mobility of N-alkyl nicotinamides and their solubilization equilibria in surfactant micellar solution were investigated using an NMR paramagnetic relaxation method. The spin-lattice relaxation times (Tl) . for protons of these compounds were measured in pure D20 and in cationic surfactant solution in the presence and absence of · a low concentration of paramagnetic Ma2+ ions. The rotational motion of these molecules in aqueous phase became slower when the alkyl group changed from methyl to octyl. The increase of the 1H spinlattice relaxation rate (Rl) of the molecules, when surfactants are added, implies the penetration of these solubilizates into micellar phase. The micelle to water phase distribution coefficient, 1-p, was determined by monitoring the change of Rl of the solubilizates upon addition of paramagnetic ions to the aqueous phase. The mole fraction based distribution coefficient, Kx, as well as the free energy of transfer of N-alkyl nicotinamides from the aqueous phase to the micellar phase were calculated. A model was postulated for the interaction of N -alkyl nicotinamide with micelles. Hydrophobic force between the alkyl chains of the solubilizates and the surfactants accounts for the solubilization of N -alkyl nicotinamides and can force the binding of cationic compounds to cationic micelles · despite charge repulsion. With increasing of the alkyl chain length, the hydrophobic force increases, and the interaction between them becomes stronger, and more N -alkyl nicotinamides are solubilizated into the micellar phase.
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Dennis, Kim Jason. "Use of isomerizable N-alkylmerocyanine dyes to robe molecular interactions within micellar solubilization sites." Scholarly Commons, 1986. https://scholarlycommons.pacific.edu/uop_etds/2116.

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Effects of aqueous surfactant solutions upon cis/trans isomerization reactions of various N-alkyl-merocyanine dyes (II) were studied. Dramatic rate enhancements were found for all dyes in CTAB and SDS solutions above the CMC. CTAB solutions showed the greatest effect with some dye isomerizations catalyzed in excess of 1000-fold. Increases in either CTAB concentration or dye isomerization rates. N-methyl through N-pentyl dye isomerization rates were measured as a function of CTAB concentration and the data treated according to the pseudophase model for micellar catalysis. KS values ranged from 198 to 2000 M-1 for N-methyl to N-pentyl dyes, respectively. Micellar rate constants also increased as dye hydrophobicity was increased. Thermodynamic activation parameters were determined for N-methyl through N-hexylmerocyanine dyes in CTAB solutions. Rate enhancements in CTAB (above the CMC) relative to those in purely aqueous solutions were shown to be due to a substantial lowering of ΔH‡, for the various dyes. Increased CTAB concentrations of N-methyl dye solutions gave reaction rate increases resulting from a lowering of ΔS‡. In 0.054 M CTAB, increases in reaction rates with increased N-alkyl chain length were due to large increases ΔS‡ (from ca. 0 eu for N-methyl to 13 eu for N-hexyl). The data were discussed in terms of molecular interactions which can occur within the micellar solubilization sites.
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Stoja, Obradović. "Termodinamička stabilnost binarnih mešovitih micela odabranih homologa iz grupa Brij surfaktanata i polisorbata." Phd thesis, Univerzitet u Novom Sadu, Medicinski fakultet u Novom Sadu, 2017. https://www.cris.uns.ac.rs/record.jsf?recordId=104920&source=NDLTD&language=en.

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Uloga micela u razvoju farmaceutskih oblika zasniva se na njihovom potencijalu da kao transportni sistemi povećaju bioraspoloživost lekovite supstance i unaprede njen farmakokinetski profil. Micele mogu da modifikuju propustljivost biološkuh membrana, omoguće kontrolisano oslobađanje lekovite supstance iz farmaceutskog oblika, stabilizuju lekovitu supstancu, itd. Kombinovanje različitih surfaktanata kao gradivih jedinica omogućava konstruisanje micela sa poželjnim fizičko-hemijskim karakteristikama. Takođe, mešovite micele između čijih gradivnih jedinica postoje sinergističke interakcije se formiraju na nižim koncentracijama surfaktanata u poređenju sa monokomponentnim micelama. U doktorskoj disertaciji je ispitana termodinamička stabilnost binarnih mešovitih micela Brij S10 i Brij S20 surfaktanata sa polisorbatom 20, polisorbatom 60 i polisorbatom 80 kao kosurfaktantima. Analiziran je uticaj građe odabranih nejonskih surfaktanata na fizičko-hemijske parametre i stabilnost njihovih mešovitih micela. Vrednosti kritične micelarne koncentracije su dobijene spektrofluorimetrijskim merenjima. Da bi se analizirao uticaj temperature na termodinamičku stabilnost micela, merenja su vršena na sledećim temperaturama: 273.15 K, 283.15 K, 293.15 K, 303.15 K i 313.15 K. Rezultati su tumačeni sa aspekta teorije regularnih rastvora (regular solution theory – RST), uz primenu Porterove jednačine. Na osnovu rezultata istraživanja, predloženi su modeli monokomponentnih i binarnih mešovitih micela. Utvrđeno je da u svim analiziranim binarnim mešovitim sistemima postoji dodatna entropija. Može se doneti zaključak da pretpostavka RST o isključivo entalpijskoj prirodi dodatne Gibsove energije nije primenljiva na ispitivane binarne sisteme. Utvrđeno je da postojanje razlike u dužini hidrofobnih segmenata monomera dodatno stabilizuje mešovitu micelu. Sa porastom temperature, ovaj stabilizacioni efekat entropijskog porekla postaje izraženiji. Prisustvo dvostruke veze u ugljovodoničnom lancu polisorbata 80 doprinosi povećanoj rigidnosti njegovih molekula. Rezultat je smanjena termodinamička stabilnost mešovitih micela koje sadrže polisorbat 80 u poređenju sa mešovitim micelama koje sadrže njegov zasićeni homolog, polisorbat 60. Utvrđeno je da razlika u dužini polarnih segmenata monomera koji grade mešovitu micelu utiče na stepen hidratacije micele, a time i na njenu stabilnost.
The role of the micelles in pharmaceutical formulation lies in their ability to, when used as drug delivery systems, increase the bioavailability of the drug and enhance its pharmacokinetic profile. Micelles may modify the permeability of biomembranes, enable controlled release from drug delivery systems, stabilize the drug, etc. By combining different surfactants as building units it is possible to engineer micelles with favorable physicochemical characteristics. Also, the mixed micelles between whose building units synergistic interactions exist are formed on lower concentrations of surfactants in comparison to single-component micelles. In the doctoral dissertation the thermodynamic stability of binary mixed micelles built of Brij S10 and Brij S20 with polysorbate 20, polysorbate 60 and polysorbate 80 as co-surfactants is examined. The influence of the structure of selected nonionic surfactants on physicochemical parameters and the stability of their mixed micelles is analyzed. Critical micelle concentration values were obtained by spectrofluorimetric measurements. In order to analyze the influence of the temperature on the micelles’ thermodynamic stability, measurements were conducted on following temperatures: 273.15 K, 283.15 K, 293.15 K, 303.15 K and 313.15 K. Obtained results were studied using regular solution theory (RST) and Porter’s equation. Based on the research results, models of both single-component and binary mixed micelles are introduced. It is deduced that in all analyzed binary mixed systems the excess entropy exists. A conclusion can be made that the assumption of RST regarding solely enthalpic nature of the excess Gibbs energy is not applicable to investigated binary systems. The difference in the length of the hydrophobic segments of monomers additionally stabilizes the mixed micelle. With the increase in the temperature, this stabilizing effect of the entropic nature is more noticeable. The existence of the double bond in polysorbate 80 hydrocarbon chain contributes to the increased rigidity of its molecules. As a result, the thermodynamic stability of the mixed micelles containing polysorbate 80 is lesser than the stability of the mixed micelles containing its saturated homologue, polysorbate 60. It is determined that the difference in length of polar segments of mixed micelle monomers affects the micelle hydration and therefore, its stability.
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Kosta, Popović. "Termodinamička stabilnost odabranih micelarnih sistema žučnih soli značajnih za nove farmaceutske formulacije." Phd thesis, Univerzitet u Novom Sadu, Medicinski fakultet u Novom Sadu, 2017. https://www.cris.uns.ac.rs/record.jsf?recordId=104270&source=NDLTD&language=en.

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Da bi se dobio sistem surfaktanata željenih osobina moguće je hemijski modifikovati već postojeće molekule površinski aktivnih supstanci, a druga mogućnost je konstrukcija binarnih smeša surfaktanata. U farmaceutskoj i prehrambenoj industriji uveliko se primenjuju binarne smeše površinski aktivnih molekula. Ukoliko je binarna mešovita micela termodinamički stabilnija od hipotetičke idealne binarne mešovite micele, onda je kritična micelarna koncentracija binarne smeše surfaktanata niža čak i od hidrofobnije gradivne jedinice mešovite micele, što znači da je za isti efekat površinske aktivnosti potrebna manja količina binarne smeše nego čistog surfaktanta. Različite gradivne jedinice binarne micele u micelarnoj pseudofazi mogu formirati specifične regije koje mogu vezivati lekove određenih strukturnih karakteristika. Pogodno je da jedna gradivna jedinica bude krute konformacije, npr. soli žučnih kiselina, dok je druga gradivna jedinica konformaciono pokretljiva (ugljovodonični nizovi iznad C10). Na taj način se povećava zapremina hidrofobne micelarne faze u odnosu na zapreminu hidrofobne micelarne faze monokomponentne micelle konformaciono krutog surfaktanta, što povećava solubilizacioni kapacitet mešovite micele u odnosu na monokomponentnu micelu krutog surfaktanta. Povećanjem dužine ugljovodoničnog niza konformaciono pokretnog surfaktanta povećava se stepen unutrašnje pokretljivosti u hidrofobnom domenu mešovite micele, što takođe povećava verovatnoću prihvatanja molekula gosta. Micelarni sistemi, kako monokomponentnih micela tako i binarnih mešovitih micela dodatno se mogu termodinamički stabilizovati povećanjem jonske jačine rastvora. Za hidrataciju katjona troše se molekuli vode iz sistema, što povećava efekat desolvatizacije hidrofobne površine surfaktanata, pa se zbog toga pospešuje samoasocijacija.
To obtain the surfactant system with the desired properties it is possible to chemically modify existing molecules of surface active agents. The other possibility is the construction of binary mixtures of surfactants. Binary mixtures of surface active molecules are widely used In the pharmaceutical and food industry. If the binary mixture micelle is more thermodynamically stable than the hypothetical ideal binary mixed micelle, then the critical micellar concentration (CMC) of the binary mixture of surfactants is even lower than the CMC of the more hydrophobic building block of the binary mixture. That means that for the same effect of surface activity less the amount of the binary mixture than the pure surfactants is required. The different building blocks of binary micelles in micelar pseudophase can form specific regions that can bind drugs of certain structural characteristics. It is suitable that one building block is of a rigid conformation, i.e. bile acid salts, while the second building block is of a flexible conformation (above C10 hydrocarbon arrays). In this way the volume of the hydrophobic micellar phase is increased in relation to the volume of the hydrophobic micellar phase of the monocomponent micelles of conformationally rigid surfactant, which increases the capacity of solubilisation of the mixed micelles, compared to the mono-component surfactant micelle of the rigid conformation. By increasing the length of the hydrocarbon array of the the conformational flexible surfactant, the degree of internal mobility in the hydrophobic domain of mixed micelles is also increased, which also increases the likelihood of acceptance of guest molecules. Micellar systems, of both monocomponent micelles and mixed micelles can be additionally thermodynamically stabilized by increasing the ionic strength of the solution. The hydration of cations uses the molecules of water from the system, which increases the effect of desolvatisation of the hydrophobic surface of the surfactants, and therefore promotes self-association.
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Mousseau, Kenneth Scott. "Determination of critical micelle concentration of an amphiphilic siderophore." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/mousseau/MousseauK0809.pdf.

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The sodachelins are a group of six amphiphilic siderophores produced by a halophilic bacterium. Amphiphilic siderophores, such as the sodachelins, are important in the solubilization and sequestration of iron related to microbial metabolism and are also unique in their ability to form micelle and vesicular structures. This professional paper describes siderophore importance in iron bioavailability, siderophore chemistry and biological function and a thermodynamic analysis of forces that drive micellization and vesicle formation. A description of experiments conducted to isolate, separate and purify the sodachelins for the purpose of measuring their critical micelle concentration (CMC) follows the review of literature. Initial siderophore isolation was achieved using XAD-2 resin to generate a crude extract. This crude extract was then purified by HPLC, and the measurement of CMC of a single siderophore, sodachelin E, was performed with a tensiomat instrument. Crude separation by XAD resin was proven successful; XAD resin has a strong affinity for siderophores as shown by experiment with the siderophore desferrioxamine B (DFB) as a control. Purification of the crude siderophore extract by only one pass on the HPLC was proven insufficient to generate a single, pure siderophore. At least a second pass on the HPLC is required to remove all contaminants. The protocol developed for CMC analysis is consistent and accurate based on a sodium dodecyl sulfate (SDS) control experiment. An approximate CMC value of 140 micron for sodachelin E was obtained, however, HPLC analysis showed contamination of another sodachelin and possible other organic solutes, indicating that this value may be inaccurate.
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Kitchens, Christopher Lawrence Roberts Christopher B. "Metallic nanoparticle synthesis within reverse micellar micromulsion systems." Auburn, Ala., 2004. http://repo.lib.auburn.edu/EtdRoot/2004/FALL/Chemical_Engineering/Dissertation/kitchcl_13_Dissertation(abbrv).pdf.

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Slaymaker, Elizabeth Ann. "Effects of surface active agents on drop size in liquid-liquid systems." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/10260.

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Tucker, Ian Malcolm. "The surface and solution properties of complex mixed surfactant systems." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670103.

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Staggemeier, Bethany Ann. "Dynamic surface tension detection : novel applications to continuous flow analysis and interfacial analysis /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/11584.

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Howell, Desiree Pearl. "Evaluation of surfactants for the enhancement of PCB degradation." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20746.

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Books on the topic "Surface active agents. Surface chemistry. Micelles"

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Serdi͡uk, A. I. Mit͡selli͡arnye perekhody v rastvorakh poverkhnostno-aktivnykh veshchestv. Kiev: Nauk. dumka, 1987.

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O'Lenick, Anthony J. Surfactants: Chemistry and properties. Carol Stream, IL: Allured Pub. Corp., 1999.

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O'Lenick, Anthony J. Surfactants: Strategic personal care ingredients. Carol Stream, IL: Allured Pub. Corp., 2004.

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Myers, Drew. Surfactant science and technology. 3rd ed. Hoboken, NJ: J. Wiley, 2005.

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Rosen, Milton J. Surfactants and interfacial phenomena. 3rd ed. Hoboken, N.J: Wiley-Interscience, 2004.

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O'Lenick, Anthony J. Surfactants: Strategic personal care ingredients. Carol Stream, IL: Allured Pub. Corp., 2005.

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Rosen, Milton J. Surfactants and interfacial phenomena. 2nd ed. New York: Wiley, 1989.

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Myers, Drew. Surfactant science and technology. 2nd ed. New York: VCH Publishers, 1992.

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E, Pelezetti, ed. Surfactants in analytical chemistry: Applications of organized amphiphilic media. Amsterdam: Elsevier, 1996.

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Paul, Bidyut K., and Satya P. Moulik. Ionic liquid-based surfactant science: Formulation, characterization and applications. Hoboken, New Jersey: John Wiley & Sons, 2015.

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Book chapters on the topic "Surface active agents. Surface chemistry. Micelles"

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Moroi, Yoshikiyo. "Surface-Active Agents." In Micelles, 7–24. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4899-0700-4_2.

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Aveyard, Bob. "What are surfactants?" In Surfactants, 3–16. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198828600.003.0001.

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Surface active agents (surfactants) are molecules or ions with a dual nature. One or more moieties in a surfactant are ‘water-hating’ (hydrophobic) ‘tail’ groups and one or more are ‘water-liking’ (hydrophilic) ‘head’ groups. Surfactants adsorb from aqueous (or other) solution to various interfaces and in sufficiently concentrated solutions simultaneously aggregate into micelles or other structures. The tail(s) are frequently hydrocarbon or fluorocarbon groups and the head(s) can be polar or ionic. Adsorption and aggregation are often driven by removal of tails from water to an air/water or nonpolar oil/water interface, or to the interior of surfactant aggregates. The ability to adsorb and to aggregate in solution makes surfactants invaluable in industry, in nature, and in the home. Here a brief description is given of the classes of surfactant most commonly encountered, and their usefulness is mentioned. Forward reference is made to appropriate chapters where material is covered in more detail.
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Saltzman, W. Mark. "Case Studies in Drug Delivery." In Drug Delivery. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195085891.003.0016.

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This chapter illustrates the concepts presented throughout the book through the examination of three different clinical scenarios in which new methods for drug delivery are needed. Many agents cannot be administered orally because of poor absorption from the intestinal tract into the blood, yet they are rapidly eliminated once they enter the blood stream. Section 10.1 describes a controlled delivery system that produces prolonged levels of such an antiviral agent in the blood. The brain is protected from changes in blood chemistry by the blood-brain barrier; this natural defense mechanism makes drug delivery to the brain difficult. Section 10.2 describes one method for achieving prolonged concentrations of an active agent within a region of the brain. Finally, some agents are active on the skin or mucosal surfaces but must be present for long periods. Section 10.3 presents a method for prolonging the residence time of macromolecules on a mucosal surface. The three problems incorporate both aspects of the drug delivery challenge: design of methods or materials for introducing drugs into the body and optimization of the design to integrate the delivery system with the body’s natural mechanisms for distributing and eliminating foreign agents. Viral diseases are a significant cause of disability and death. Many deadly viral diseases—such as smallpox and polio—are now under control, due largely to the development of protective vaccines, but vaccines for certain viral illnesses have been difficult to develop. The development of an AIDS vaccine has been a priority among biomedical research efforts since the mid-1980s; tremendous energy and resources have been invested in this pursuit, but clinical progress towards a vaccine has been slow. On the other hand, antiviral therapies have had a significant impact on the clinical care of AIDS patients, particularly since multi-drug regimens targeting the retroviral reverse transcriptase and protease enzymes were developed in the late 1990s. However, many patients cannot tolerate aggressive antiviral therapy and development of drug-resistant viral strains is a persistent problem. Therefore, the search for alternative methods for blocking retroviral infections continues.
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Conference papers on the topic "Surface active agents. Surface chemistry. Micelles"

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Conway, Michael W., Kevin Smith, Todd Thomas, and Richard A. Schraufnagel. "The Effect of Surface Active Agents on the Relative Permeability of Brine and Gas in Porous Media." In SPE International Symposium on Oilfield Chemistry. Society of Petroleum Engineers, 1995. http://dx.doi.org/10.2118/28982-ms.

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Vasko, Christopher A., and Christina G. Giannopapa. "Liquid Droplets in Contact With Cold Non-Equilibrium Atmospheric Pressure Plasmas." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63629.

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Recently, cold, non-equilibrium atmospheric pressure plasmas (CAPs) and their active chemistry have been extensively investigated to the benefit of a wide array of applications such as biomedical and industrial applications mainly in the area of materials processing and chemical synthesis, amongst many others. In general, these plasmas operate at standard conditions (i.e. 1 atm, 300K), are small (∼ cm) and rather simple to operate in comparison to other plasmas. Their complex chemistry gives rise to a wide array of both stable and transient reactive species: such as O3, H2O2, OH and NOx, next to charged species and (V)UV-radiation. This chemistry is the reason for their wide spread application and has already found many industrial applications from waste water treatment, stain free detergents and industrial scale production of oxidants. In recent years, bactericidal effects of CAPs gained increasing attention for applications such as dermatology, disinfection, dentistry and cancer treatment or stimulated blood coagulation. This paper aims to highlight recent research into new biological applications for complex mission scenarios involving humans in remote locations using CAPs for disinfection, bleaching or wound healing. Results using radiofrequency plasma jets for the inactivation of Pseudomonas aeruginosa are summarized, highlighting the importance of liquid plasma interactions. Work with such a CAP paved the way for a promising application in the field of biomedical applications presented here. It involves surface barrier discharges which can be used to treat larger surfaces compared to jets. Their physical construction, using floating or contained electrodes, offer a convenient way of controlling electrical current on a large scale, 3D treatment of both conducting and insulating surfaces with minimal heating. These devices may be tailored to specific skin treatments, allowing fast and effective treatment of larger skin surfaces while following the shape of the skin. This might reduce the need for bactericidal agents and would be a valuable application to assist humans in remote locations. These emerging technologies could be essential both for human health care under extreme conditions, as well as for research itself (sterilisation of tools and large areas, etc.). Especially in the absence of abundant resources (antibiotic agents, disinfectants and the like) alternative approaches to support humans in isolated locations have to be developed. Applications based on a good understanding of plasma chemistry would empower health care under extreme conditions to efficiently use and manage in situ resources. Their low mass, compact size, low power consumption and high reliability could make them essential use under extreme conditions.
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Chen, Kok Hao, and Jong Hyun Choi. "Nanoparticle-Aptamer: An Effective Growth Inhibitor for Human Cancer Cells." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11966.

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Semiconductor nanocrystals have unique optical properties due to quantum confinement effects, and a variety of promising approaches have been devised to interface the nanomaterials with biomolecules for bioimaging and therapeutic applications. Such bio-interface can be facilitated via a DNA template for nanoparticles as oligonucleotides can mediate the aqueous-phase nucleation and capping of semiconductor nanocrystals.[1,2] Here, we report a novel scheme of synthesizing fluorescent nanocrystal quantum dots (NQDs) using DNA aptamers and the use of this biotic/abiotic nanoparticle system for growth inhibition of MCF-7 human breast cancer cells for the first time. Particularly, we used two DNA sequences for this purpose, which have been developed as anti-cancer agents: 5-GGT GGT GGT GGT TGT GGT GGT GGT GG-3 (also called, AGRO) and 5-(GT)15-3.[3–5] This study may ultimately form the basis of unique nanoparticle-based therapeutics with the additional ability to optically report molecular recognition. Figure 1a shows the photoluminescence (PL) spectra of GT- and AGRO-passivated PbS QD that fluoresce in the near IR, centered at approximately 980 nm. A typical synthesis procedure involves rapid addition of sodium sulfide in the mixture solution of DNA and Pb acetate at a molar ratio of 2:4:1. The resulting nanocrystals are washed to remove unreacted DNA and ions by adding mixture solution of NaCl and isopropanol, followed by centrifugation. The precipitated nanocrystals are collected and re-suspended in aqueous solution by mild sonication. Optical absorption measurements reveal that approximately 90 and 77% of GT and AGRO DNA is removed after the washing process. The particle size distribution in Figure 1b suggests that the GT sequence-capped PbS particles are primarily in 3–5 nm diameter range. These nanocrystals can be easily incorporated with mammalian cells and remain highly fluorescent in sub-cellular environments. Figure 1c serially presents an optical image of a MCF-7 cell and a PL image of the AGRO-capped QD incorporated with the cell. Figure 1. (a) Normalized fluorescence spectra of PbS QD synthesized with GT and AGRO sequences, which were previously developed as anti-cancer agents. The DNA-capped QD fluoresce in the near IR centered at ∼980 nm. (b) TEM image of GT-templated nanocrystals ranging 3–5 nm in diameter. (c) Optical image of an MCF-7 human breast cancer cell after a 12-hour exposure to aptamer-capped QD. (d) PL image of AGRO-QD incorporated with the cell, indicating that these nanocrystals remain highly fluorescent in sub-cellular environments. One immediate concern for interfacing inorganic nanocrystals with cells and tissue for labeling or therapeutics is their cytotoxicity. The nanoparticle cytotoxicity is primarily determined by material composition and surface chemistry, and QD are potentially toxic by generating reactive oxygen species or by leaching heavy metal ions when decomposed.[6] We examined the toxicity of aptamer-passivated nanocrystals with NIH-3T3 mouse fibroblast cells. The cells were exposed to PbS nanocrystals for 2 days before a standard MTT assay as shown in Figure 2, where there is no apparent cytotoxicity at these doses. In contrast, Pb acetate exerts statistically significant toxicity. This observation suggests a stable surface passivation by the DNA aptamers and the absence of appreciable Pb2+ leaching. Figure 2. Viability of 3T3 mouse fibroblast cells after a 2-day exposure to DNA aptamer-capped nanocrystals. There is no apparent dose-dependent toxicity, whereas a statistically significant reduction in cell viability is observed with Pb ions. Note that Pb acetate at 133 μM is equivalent to the Pb2+ amount that was used for PbS nanocrystal synthesis at maximum concentration. Error bars are standard deviations of independent experiments. *Statistically different from control (p<0.005). Finally, we examined if these cyto-compatible nanoparticle-aptamers remained therapeutically active for cancer cell growth inhibition. The MTT assay results in Figure 3a show significantly decreased growth of breast cancer cells incorporated with AGRO, GT, and the corresponding templated nanocrystals, as anticipated. In contrast, 5-(GC)15-3 and the QDs synthesized with the same sequence, which were used as negative controls along with zero-dose control cells, did not alter cell viability significantly. Here, we define the growth inhibition efficacy as (100 − cell viability) per DNA of a sample, because the DNA concentration is significantly decreased during the particle washing. The nanoparticle-aptamers demonstrate 3–4 times greater therapeutic activities compared to the corresponding aptamer drugs (Figure 3b). We speculate that when a nanoparticle-aptamer is internalized by the cancer cells, it forms an intracellular complex with nucleolin and nuclear factor-κB (NF-κB) essential modulator, thereby inhibiting NF-κB activation that would cause transcription of proliferation and anti-apoptotic genes.[7] The nanoparticle-aptamers may more effectively block the pathways for creating anti-apoptotic genes or facilitate the cellular delivery of aptamers via nanoparticle uptake. Our additional investigation indicates that the same DNA capping chemistry can be utilized to produce aptamer-mediated Fe3O4 nanocrystals, which may be potentially useful in MRI and therapeutics, considering their magnetic properties and biocompatibility. In summary, the nanoparticle-based therapeutic schemes developed here should be valuable in developing a multifunctional drug delivery and imaging agent for biological systems. Figure 3. Anti-proliferation of MCF-7 human breast cancer cells with aptamer-passivated nanocrystals. (a) Viability of MCF-7 cells exposed to AGRO and GT sequences, and AGRO-/GT-capped QD for 7 days. The DNA concentration was 10 uM, while the particles were incubated with cells at 75 nM. (b) Growth inhibition efficacy is defined as (100 − cell viability) per DNA to correct the DNA concentration after particle washing.
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