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Tian, Maozhang, Fan Zhang, Lu Wang, Xing Dong, Lifei Zhang et Xia Guo. « Activity of Polyphenoloxidase in red Fuji Apples Promoted with Cationic Surfactant – Role of Surfactant Structure ». Tenside Surfactants Detergents 58, no 5 (1 septembre 2021) : 383–93. http://dx.doi.org/10.1515/tsd-2020-2322.
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Abstract In this study, we observed the activity of polyphenoloxidase (PPO) in red Fuji apples in the presence of single-chained surfactants (including cetyl trimethyl ammonium bromide (CTAB), and dodecyl trimethyl ammonium bromide (DTAB)) and gemini surfactants (pentamethylene-α,ω-bis(dodecyl dimethyl ammonium bromide), octamethylene-α,ω-bis(dodecyl dimethyl ammonium bromide, dodecamethylene-α,ω-bis(dodecyl dimethyl ammonium bromide), pentamethylene-α,ω-bis(cetyl dimethyl ammonium bromide), and octamethylene-α,ω-bis(cetyl dimethyl ammonium bromide)). It was found that all these surfactants enhanced the activity of PPO in a wide range of temperature at low content. When PPO was denatured by incubating at high temperature, the surfactants caused reactivation of PPO. Compared to the single-chained surfactants, the gemini surfactants increased PPO activity at a much lower concentration. Moreover, the single-chained surfactant and the gemini surfactant acted together to further increase PPO activity, and the synergistic effect reduced the amount of surfactant used. In addition, the Michaelis-Menten constant for PPO did not change in the presence of the surfactants, suggesting the active site should remain well with the surfactants.
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Wang, Ruiguo, Xinxin Xu, Xiaodi Shi, Junjie Kou, Hongjian Song, Yuxiu Liu, Jingjing Zhang et Qingmin Wang. « Promoting Efficacy and Environmental Safety of Pesticide Synergists via Non-Ionic Gemini Surfactants with Short Fluorocarbon Chains ». Molecules 27, no 19 (10 octobre 2022) : 6753. http://dx.doi.org/10.3390/molecules27196753.
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Improving the utilization rate of pesticides is key to achieve a reduction and synergism, and adding appropriate surfactant to pesticide preparation is an effective way to improve pesticide utilization. Fluorinated surfactants have excellent surface activity, thermal and chemical stability, but long-chain linear perfluoroalkyl derivatives are highly toxic, obvious persistence and high bioaccumulation in the environment. Therefore, new strategies for designing fluorinated surfactants which combine excellent surface activity and environmental safety would be useful. In this study, four non-ionic gemini surfactants with short fluorocarbon chains were synthesized. The surface activities of the resulting surfactants were assessed on the basis of equilibrium surface tension, dynamic surface tension, and contact angle. Compared with their monomeric counterparts, the gemini surfactants had markedly lower critical micelle concentrations and higher diffusivities, as well as better wetting abilities. We selected a single-chain surfactant and a gemini surfactant with good surface activities as synergists for the glyphosate water agent. Both surfactants clearly improved the efficacy of the herbicide, but the gemini surfactant had a significantly greater effect than the single-chain surfactant. An acute toxicity test indicated that the gemini surfactant showed slight toxicity to rats.
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SMIT, B., P. A. J. HILBERS et K. ESSELINK. « COMPUTER SIMULATIONS OF SURFACTANT SELF ASSEMBLY ». International Journal of Modern Physics C 04, no 02 (avril 1993) : 393–400. http://dx.doi.org/10.1142/s0129183193000422.
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A simple oil/water/surfactant model is used to study the self-assembly of surfactants. The model contains only the most obvious elements: oil and water do not mix, and a surfactant is an amphiphilic molecule, i.e. one side of the molecule likes oil but dislikes water, the other side likes water but dislikes oil. Computer simulations on large oil/water/surfactant systems were performed on a network of 400 transputers using a parallel molecular dynamics algorithm. The simulations yield a complete micellar size distribution function. Furthermore, we observe (equilibrium) dynamical processes such as the entering of single surfactants into micelles, single surfactants leaving micelles, the fusion of two micelles, and the slow breakdown of a micelle.
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Desai, Tejas R., et Sharad G. Dixit. « Adsorption from Mixtures of Cationic/Non-Ionic Surfactants on to a Polystyrene Surface ». Adsorption Science & ; Technology 15, no 5 (mai 1997) : 391–405. http://dx.doi.org/10.1177/026361749701500507.
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The adsorption of cetyltrimethylammonium bromide (CTAB) and nonyl phenyl ethoxylates (NP-n, where n = 13, 20 and 30) on to polystyrene powder has been studied. Concentrations of surfactant solutions ranging from below CMC to well above CMC were investigated. In a single surfactant system, only the cationic surfactant (CTAB) was found to adsorb appreciably while nonionic surfactants showed negligible adsorption. In mixed surfactant systems, the cationic surfactant was found to induce significant co-adsorption of non-ionic surfactants. The increased adsorption of non-ionic surfactants has been attributed to the formation of non-ideal mixed hemimicelles due to intercomponent lateral interactions. However, non-ionic surfactants with longer hydrophilic chains did not form mixed hemimicelles with CTAB. In general, zeta potential measurements support the adsorption results.
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Abdel-Rahem, Rami A., Sana Niaz, Abdelmnim M. Altwaiq, Muayad Esaifan, Mohammad Bassam Al Bitar et Abeer Al Bawab. « Synergistic interaction between sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine oxide (DDAO) and their adsorption onto activated charcoal and Jordanian natural clay ». Tenside Surfactants Detergents 59, no 2 (28 février 2022) : 144–58. http://dx.doi.org/10.1515/tsd-2021-2395.
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Abstract Solutions of sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine oxide (DDAO) with mole fractions of 0.00, 0.25, 0.50, 0.75 and 1.00 were prepared and their surface tension was measured as a function of total surfactant concentration. The critical micelle concentration (CMC) values of these mixed solutions were also determined. The minimum area occupied by a surfactant molecule at air/water interface was calculated for single and binary surfactant mixtures. A pronounced synergistic interaction between SDBS and DDAO was detected. The surface tension and CMC-values of SDBS/DDAO mixtures are significantly lower than those of the single surfactant. The mixed system of SDBS/DDAO exhibits a highly negative interaction parameter (β = −10.6) according to regular solution model, and is found to fulfill the condition of Hua and Rosen, indicting a strong synergistic interaction between the two surfactants. The contact angle measurements show the wettability of the surfactant mixture onto polyethylene substrate is higher than of the respective single surfactant. In addition, the adsorption of SDBS and DDAO or their mixtures on 1.0% activated carbon and 5.0% Jordanian natural clay (JNC), respectively, was investigated using the depletion method. The individual surfactants were found to adsorb to a considerable extent on activated carbon, and a slightly higher adsorption tendency was even measured for mixed SDBS/DDAO surfactant systems. Although no SDBS molecules adsorbed on JNC, adsorption was observed for solutions containing DDAO and SDBS/DDAO surfactants. The improvement in wettability and adsorption of SDBS/DDAO surfactants at the air/water and solid/water interfaces is directly related to the synergistic interaction between the two surfactants.
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Mucic, Nenad, Jelena Skrbic, Sandra Bucko, Lidija Petrovic, Jaroslav Katona, Valentin B. Fainerman, Eugene V. Aksenenko, Emanuel Schneck et Reinhard Miller. « Adsorption of Equimolar Mixtures of Cationic and Anionic Surfactants at the Water/Hexane Interface ». Colloids and Interfaces 5, no 1 (24 décembre 2020) : 1. http://dx.doi.org/10.3390/colloids5010001.
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In mixed solutions of anionic and cationic surfactants, called catanionics, ion pairs are formed which behave like non-ionic surfactants with a much higher surface activity than the single components. In equimolar mixtures of NaCnSO4 and CmTAB, all surface-active ions are paired. For mixtures with n + m = const, the interfacial properties are rather similar. Catanionics containing one long-chain surfactant and one surfactant with medium chain length exhibit a strong increase in surface activity as compared with the single compounds. In contrast, catanionics of one medium- and one short chain surfactant have a surface activity similar to that of the medium-chain surfactant alone. Both the Frumkin model and the reorientation model describe the experimental equilibrium data equally well, while the adsorption kinetics of the mixed medium- and short-chain surfactants can be well described only with the reorientation model.
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Zhang, Yongmin, Zhiqiang Chen et Yong Zhao. « Viscoelastic micellar solution formed by a Se-based ionic liquid surfactant and its response to redox changes ». Physical Chemistry Chemical Physics 21, no 27 (2019) : 14734–44. http://dx.doi.org/10.1039/c9cp01256g.
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The incorporation of a Se atom endows the surfactants with redox-sensitivity, and that its site plays a crucial role both in single surfactant solution and viscoelastic micellar solution formed by surfactant and NaSal.
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Walker, S., E. Naranjo, S. Chiruvolu et J. Zasadzinski. « TEM investigations of self-assembly through physical synthesis ». Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994) : 436–37. http://dx.doi.org/10.1017/s0424820100169912.
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A novel way of enlarging the realm of surfactant solution microstructure is the "physical synthesis" of new microstructures and surfactant-templated materials by mixing simple surfactants or surfactant and inorganic and ionic species. Mixing can often produce properties not possessed by any one species alone. As we have recently shown, mixtures of single-tailed cationic and anionic surfactants associate in solution to form a quasi-double-tailed catanionic surfactant that forms bilayers rather than the simple micelles each species would form on its own. Mixed surfactant systems apparently produce new microstructures by altering the intermolecular and interaggregate forces in ways impossible for single component systems. In addition to spontaneous vesicles, we have found other new microstructures including dilute lamellar and L3 phases depending on the details of the surfactant mixture. Surfactant interactions with ionic species also play an important role in the in synthesis of a new M41S family of mesoporous silicas, and are likely to be important in the templating of biominerals at interfaces. By understanding the molecular and chemical basis of these interactions, we can begin to tailor new microstructured and/or biomimetic materials by controlling surfactant aggregation and phase behavior through physical synthesis rather than through much more elaborate chemical synthesis.
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Hassan, Mohammed, Sadeq M. Al-Hazmi, Ibrahim A. Alhagri, Ahmed N. Alhakimi, Adnan Dahadha, Mohammad Al-Dhoun et Yazan Batineh. « Micellar Catalysis of Chemical Reactions by Mixed Surfactant Systems and Gemini Surfactants ». Asian Journal of Chemistry 33, no 7 (2021) : 1471–80. http://dx.doi.org/10.14233/ajchem.2021.23187.
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Micellar catalysis exhibited by mixed surfactant systems and gemini surfactants was reviewed. The review focused on mixed surfactant systems and tried to correlate the changes in the physico-chemical properties of these systems to the variations of their catalytic activities. Mixed surfactant systems are promising as the catalytic efficiency of some single surfactants was significantly enhanced in the presence of other critically selected surfactants. The selection should consider the charge, size, and structures of the head group as well as an appropriate length of hydrocarbon tail. The overall conclusion has arrived the mixed surfactant systems could be a tool by which the reaction rate can be tuned by changing the composition and/or the components’ structures. The higher catalytic activity of gemini surfactants compared to conventional ones, their facile synthesis and liability for structure control made them of superior choice for micellar catalysis.
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Miao, Zong Cheng, Yi Wei Wang, Xing Zhang, Lei Zhang, Zhi Xue Wang et Yuan Yuan Li. « Antimicrobial Study of Symmetrical Gemini Cationic Surfactant Based on N-Hexadecyldimethylamine ». Key Engineering Materials 575-576 (septembre 2013) : 245–48. http://dx.doi.org/10.4028/www.scientific.net/kem.575-576.245.
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Gemini surfactants generally exhibit superior properties to those of their single-chain analogues with a similar chain length and head group, especially for gemini cationic surfactants. Gemini cationic surfactants have recently attracted considerable attention due to the increasing microbial resistance to common quaternary ammonium compounds. A novel symmetrical gemini cationic surfactant based onn-hexadecyldimethylamine was synthesized through epichlorohydrin andn-hexadecyldimethylamine as rude materials. The chemical structure of the product was confirmed using1H-NMR and FT-IR. The minimum inhibitory concentration of the surfactant toescherichia colirises to 100 ppm, and a higher concentration surely contributes to increase its effect, butstaphylococcus aureusis immune to this surfactant.
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Lamch, Łukasz, Weronika Szczęsna, Sebastian J. Balicki, Marcin Bartman, Liliana Szyk-Warszyńska, Piotr Warszyński et Kazimiera A. Wilk. « Multiheaded Cationic Surfactants with Dedicated Functionalities : Design, Synthetic Strategies, Self-Assembly and Performance ». Molecules 28, no 15 (1 août 2023) : 5806. http://dx.doi.org/10.3390/molecules28155806.
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Contemporary research concerning surfactant science and technology comprises a variety of requirements relating to the design of surfactant structures with widely varying architectures to achieve physicochemical properties and dedicated functionality. Such approaches are necessary to make them applicable to modern technologies, such as nanostructure engineering, surface structurization or fine chemicals, e.g., magnetic surfactants, biocidal agents, capping and stabilizing reagents or reactive agents at interfaces. Even slight modifications of a surfactant’s molecular structure with respect to the conventional single-head–single-tail design allow for various custom-designed products. Among them, multicharge structures are the most intriguing. Their preparation requires specific synthetic routes that enable both main amphiphilic compound synthesis using appropriate step-by-step reaction strategies or coupling approaches as well as further derivatization toward specific features such as magnetic properties. Some of the most challenging aspects of multicharge cationic surfactants relate to their use at different interfaces for stable nanostructures formation, applying capping effects or complexation with polyelectrolytes. Multiheaded cationic surfactants exhibit strong antimicrobial and antiviral activity, allowing them to be implemented in various biomedical fields, especially biofilm prevention and eradication. Therefore, recent advances in synthetic strategies for multiheaded cationic surfactants, their self-aggregation and performance are scrutinized in this up-to-date review, emphasizing their applications in different fields such as building blocks in nanostructure engineering and their use as fine chemicals.
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Morzy, Diana, Michael Schaich et Ulrich F. Keyser. « A Surfactant Enables Efficient Membrane Spanning by Non-Aggregating DNA-Based Ion Channels ». Molecules 27, no 2 (17 janvier 2022) : 578. http://dx.doi.org/10.3390/molecules27020578.
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DNA nanotechnology makes use of hydrophobically modified constructs to create synthetic membrane protein mimics. However, nucleic acid structures exhibit poor insertion efficiency, leading to a low activity of membrane-spanning DNA protein mimics. It is suggested that non-ionic surfactants improve insertion efficiency, partly by disrupting hydrophobicity-mediated clusters. Here, we employed confocal microscopy and single-molecule transmembrane current measurements to assess the effects of the non-ionic surfactant octylpolyoxyethylene (oPOE) on the clustering behavior and membrane activity of cholesterol-modified DNA nanostructures. Our findings uncover the role of aggregation in preventing bilayer interactions of hydrophobically decorated constructs, and we highlight that premixing DNA structures with the surfactant does not disrupt the cholesterol-mediated aggregates. However, we observed the surfactant’s strong insertion-facilitating effect, particularly when introduced to the sample separately from DNA. Critically, we report a highly efficient membrane-spanning DNA construct from combining a non-aggregating design with the addition of the oPOE surfactant.
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Huang, Xiangrong, Zhicheng Ye, Yazhuo Shang, Yifan He, Hong Meng, Yinmao Dong, Zhaohui Qu, Youting Liu, Shouhong Xu et Honglai Liu. « Effect of Single/Mixed Surfactant Systems on Orientations of Liquid Crystals and Interaction of Proteins with Surfactants at Fluid Interfaces ». Australian Journal of Chemistry 74, no 8 (2021) : 591. http://dx.doi.org/10.1071/ch21063.
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A series of single surfactant systems, i.e, quaternary ammonium-based gemini surfactants with different spacers and alkyl chain lengths (m-n-m; m=12, n=2, 3, 4, 6; n=3, m=12, 14, 16), halogen-free surface-active ionic liquid (HF-SAILs) with different symmetries ([Cnmim][C12H25SO4]; n=6, 8, 10, 12), and single-chain cationic surfactants including 1-dodecyl-3-methylimidazolium bromide ([C12mim]Br) and dodecyltrimethylammonium bromide (DTAB), along with certain combinations of different surfactants (12-3-12/[C12mim]Br and 12-3-12/DTAB) were applied to an aqueous/liquid crystal interface (ALI). All the surfactants could induce an orientational transition of liquid crystals (LCs) from a planar to homeotropic state, which caused a bright-to-dark optical shift. It was proved that double-chain surfactants and the mixed surfactants inclined to adsorb at the ALI triggering the orientational transition. Inspiringly, a quicker and more sensitive dark-to-bright optical response was observed for mixed surfactant system-decorated interfaces in contact with proteins (such as bovine serum albumin (BSA), lysozyme, and trypsin) as opposed to the single surfactant systems. The ALI decorated by the 12-3-12/[C12mim]Br system was particularly efficient and exhibited the most sensitive optical response for BSA (0.01ngmL−1). The order parameters (SCD) of surfactants tails at the interface and the free energy of proteins with 12-3-12 and [C12mim]Br were calculated, respectively. The results explain that the 12-3-12/[C12mim]Br-laden ALI shows a quicker and more sensitive optical response for BSA. This work inspired us to study mixed surfactant systems-decorated LC interfaces and further provides new insights for different chemical and biological applications.
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Vinson, Phillip K. « Cryo-TEM of CTAB micelles and microemulsions ». Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988) : 112–13. http://dx.doi.org/10.1017/s042482010010264x.
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Single-tailed surfactant molecules in aqueous solutions can associate into several different microstructural forms within a one-phase region of the phase diagram (Fig. 1). The molecules associate into globular aggregates called spherical micelles above a surfactant concentration called the critical micelle concentration, or cmc. At higher surfactant concentrations some surfactants will associate into rod-like micelles called cylindrical micelles. In systems containing ionic surfactants the transition from spherical to cylindrical micelles can be brought about at lower surfactant concentrations by adding an electrolyte. The electrolyte screens the electrostatic repulsion between surfactant head groups and allows formation of the lower mean curvature cylindrical microstructures. Micellar aggregates are equilibrium microstructures in which the nonpolar (often hydrocarbon or fluorocarbon) moieties of the surfactant molecules are shielded from the aqueous medium by the water-soluble moieties of the surfactant molecules. The solubilization of oil into the nonpolar micelle interior produces an aqueous solution of oil swollen micelles, i.e., a microemulsion.
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Fardous, Jannatul, Faria Farzana Perveen, Md Ohidullah, AHM Saifuddin et Sakina Sultana. « Effects of concentration and synergism on drug solubilising behaviour of PVP K 30 and PEG 6000 ». Jahangirnagar University Journal of Biological Sciences 3, no 2 (19 juin 2016) : 49–55. http://dx.doi.org/10.3329/jujbs.v3i2.28285.
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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.Jahangirnagar University J. Biol. Sci. 3(2): 49-55, 2014 (December)
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Wang, Biao, Xue Wang, Futang Hu, Xiangyu Wang, Zhongji Yang, Xiuyu Zhu, Gen Li et Keliang Wang. « Study on the Properties of Compound Surfactants with PO Groups ». Energies 17, no 2 (20 janvier 2024) : 513. http://dx.doi.org/10.3390/en17020513.
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The compound surfactant system has considerable development prospects for improving oil recovery. A synergistic effect can be achieved through the orderly arrangement of the two surfactants on the interface, which can make up for the performance defects of a single surfactant. In this paper, the effects of the number of propylene oxides (PO) in composite surfactants on interfacial tension and emulsion stability were systematically studied. The results showed that the solubility of composite surfactants was significantly improved under high-salinity conditions by adding anionic–nonionic surfactants to a single anionic surfactant. The interfacial tension of composite surfactants shows a V-shaped change of first decreasing and then increasing with the increase in PO groups. As the number of PO groups increases, the emulsion first increases and then decreases. Among the series of composite surfactants, LBAS/C12PO10S has the lowest interfacial tension, reaching the order of 10−3 mN/m, and the emulsion formed by it exhibits superior stability. This indicates that the synergistic effect of the two surfactants can be improved by adjusting the number of PO groups. Furthermore, the LBAS/C12PO10S composite system can be mixed with crude oil to form Winsor III microemulsion, which has great potential for application in enhanced oil recovery via chemical flooding.
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Petrovic, Lidija, Verica Sovilj, Jadranka Milanovic et Jaroslav Katona. « A conductometric investigation of hydroxypropylmethyl cellulose/sodium dodecyl sulfate/nonionic surfactant systems ». Journal of the Serbian Chemical Society 79, no 11 (2014) : 1421–32. http://dx.doi.org/10.2298/jsc140321059p.
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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 40?C 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.
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Suresh, G. K., et R. F. Soll. « Exogenous Surfactant Therapy in Newborn Infants ». Annals of the Academy of Medicine, Singapore 32, no 3 (15 mai 2003) : 335–45. http://dx.doi.org/10.47102/annals-acadmedsg.v32n3p335.
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Exogenous surfactant therapy has an established role in the management of neonatal respiratory distress syndrome (RDS). This article summarises the current evidence on surfactant therapy. The use of surfactant for the treatment or prophylaxis of neonatal RDS results in a 30% to 65% relative reduction in the risk of pneumothorax and up to a 40% relative reduction in the risk of mortality. Adverse effects, of which pulmonary haemorrhage is of most concern, are infrequent and long-term follow-up studies of treated patients are reassuring. Natural surfactants have advantages over synthetic surfactants, including a lower frequency of pneumothorax and a lower mortality. Prophylactic administration of surfactant is preferred over ‘rescue’ administration, especially in infants of <30 weeks’ gestation, as it decreases the risk of pneumothorax, pulmonary interstitial emphysema and neonatal mortality. Prophylaxis can be administered after initial resuscitation and stabilisation. In preterm infants who do not receive prophylactic surfactant, the first dose of surfactant should be administered as early as possible – early selective treatment decreases the risk of pneumothorax, pulmonary interstitial emphysema, chronic lung disease and neonatal mortality. A regimen of using multiple doses of surfactant if required has advantages over a single dose regimen. Exogenous surfactant therapy has also been used in neonatal respiratory disorders other than RDS. In trials in severe meconium aspiration syndrome, surfactant therapy reduced the need for extracorporeal membrane oxygenation. Its role in other disorders requires testing. The development and testing of newer surfactants is in progress.
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Pesci, Chiara, Andre Weiner, Holger Marschall et Dieter Bothe. « Computational analysis of single rising bubbles influenced by soluble surfactant ». Journal of Fluid Mechanics 856 (9 octobre 2018) : 709–63. http://dx.doi.org/10.1017/jfm.2018.723.
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This paper presents novel insights into the influence of soluble surfactants on bubble flows obtained by direct numerical simulation (DNS). Surfactants are amphiphilic compounds which accumulate at fluid interfaces and significantly modify the respective interfacial properties, influencing also the overall dynamics of the flow. With the aid of DNS, local quantities like the surfactant distribution on the bubble surface can be accessed for a better understanding of the physical phenomena occurring close to the interface. The core part of the physical model consists of the description of the surfactant transport in the bulk and on the deformable interface. The solution procedure is based on an arbitrary Lagrangian–Eulerian (ALE) interface-tracking method. The existing methodology was enhanced to describe a wider range of physical phenomena. A subgrid-scale (SGS) model is employed in the cases where a fully resolved DNS for the species transport is not feasible due to high mesh resolution requirements and, therefore, high computational costs. After an exhaustive validation of the latest numerical developments, the DNS of single rising bubbles in contaminated solutions is compared to experimental results. The full velocity transients of the rising bubbles, especially the contaminated ones, are correctly reproduced by the DNS. The simulation results are then studied to gain a better understanding of the local bubble dynamics under the effect of soluble surfactant. One of the main insights is that the quasi-steady state of the rise velocity is reached without ad- and desorption being necessarily in equilibrium.
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Hao, Xi Hai, et Ying Zhe Xiao. « Research on Surface Modification of Nano-TiO2 ». Advanced Materials Research 941-944 (juin 2014) : 487–91. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.487.
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Different surfactants such as Triethanolamine, Sodium dodecyl sulfate (SDS), and Polyvinylpyrrolidone (PVP) are applied in surface modification of nanoTiO2. The dispersion of nanopowder processed with different surfactants in water is evaluated using settlement method, in order to make more even composite films. The result shows that dispersion effect will be better when Triethanolamine is combined with the other two types of surfactants than only single type of surfactant is used. The best surfactant for dispersing nanoTiO2 is the mixture of Triethanolamine and Sodium dodecyl sulfate with mass ratio of 2:1 and 30% of surfactant amount; the experiment condition is set as both stirring and ultrasound times are 15 minutes, the initial settlement time of nanoTiO2 is set as 2.5 hours, and the total settlement time is set as more than 120 hours.
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Ostos, Francisco José, José Antonio Lebrón, María Luisa Moyá, Eva Bernal, Ana Flores, Cristian Lépori, Ángeles Maestre, Francisco Sánchez, Pilar López-Cornejo et Manuel López-López. « Potentiometric Study of Carbon Nanotube/Surfactant Interactions by Ion-Selective Electrodes. Driving Forces in the Adsorption and Dispersion Processes ». International Journal of Molecular Sciences 22, no 2 (15 janvier 2021) : 826. http://dx.doi.org/10.3390/ijms22020826.
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The interaction (adsorption process) of commercial ionic surfactants with non-functionalized and functionalized carbon nanotubes (CNTs) has been studied by potentiometric measurements based on the use of ion-selective electrodes. The goal of this work was to investigate the role of the CNTs’ charge and structure in the CNT/surfactant interactions. Non-functionalized single- (SWCNT) and multi-walled carbon nanotubes (MWCNT), and amine functionalized SWCNT were used. The influence of the surfactant architecture on the CNT/surfactant interactions was also studied. Surfactants with different charge and hydrophobic tail length (sodium dodecyl sulfate (SDS), octyltrimethyl ammonium bromide (OTAB), dodecyltrimethyl ammonium bromide (DoTAB) and hexadecyltrimethyl ammonium bromide (CTAB)) were studied. According to the results, the adsorption process shows a cooperative character, with the hydrophobic interaction contribution playing a key role. This is made evident by the correlation between the free surfactant concentration (at a fixed [CNT]) and the critical micellar concentration, cmc, found for all the CNTs and surfactants investigated. The electrostatic interactions mainly determine the CNT dispersion, although hydrophobic interactions also contribute to this process.
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Gull, Nuzhat, Mohd Ishtikhar, Md Sayem Alam, Syedah Noorul Sabah Andrabi et Rizwan Hasan Khan. « Spectroscopic studies on the comparative refolding of guanidinium hydrochloride denatured hen egg-white lysozyme and Rhizopus niveus lipase assisted by cationic single-chain/gemini surfactants via artificial chaperone protocol ». RSC Advances 7, no 45 (2017) : 28452–60. http://dx.doi.org/10.1039/c6ra21528a.
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Du, Bin, Shi Sheng Zhou et Nan Wang. « Modification of Printing Aluminum Powders by Wet Covering Method with Composite Surfactants ». Advanced Materials Research 179-180 (janvier 2011) : 596–601. http://dx.doi.org/10.4028/www.scientific.net/amr.179-180.596.
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Considering the fact of low gloss and masking power of aluminum powder, the aluminum powder is chemically modified by wet covering with eight kinds of single surfactants such as Oleic acid, Stearic acid, Sodium dodecyl sulfonate, Sodium stearate, Polyvinyl alcohol, Polyethylene glycol, Tween-80 and Emulsifier-OP in different proportions on the surface of aluminum powder and the gloss of aluminum paste printing ink concocted with the covered aluminum powder is tested. The results show that the gloss of the aluminum powder covered by one percent Polyvinyl alcohol increases most significant. In order to upgrade the gloss of the aluminum paste printing ink, an orthogonal experiment is carried out by choosing four surfactants such as Polyvinyl alcohol as influencing factors and their addition amounts as researched levels. The optimal surface modification formula is obtained based on the experiment. The dosage of surfactant is one percent of the aluminum powder, Sodium dodecyl sulfonate accounts for 25.00% of the total surfactant’s weight, Sodium stearate accounts for 37.50% of the total surfactant’s weight, Tween-80 accounts for 12.50% of the total surfactant and Polyvinyl alcohol accounts for 25.00% of the total surfactant’s weight. The prescription can concoct the commodity aluminum powder and passed 1200 mesh to the aluminum paste printing ink with commodity ink to satisfy the request of relief printing and intaglio printing. The gloss of the printed aluminum paste printing ink reaches 81.3.
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Patarroyo, Javier, Neus G. Bastús et Victor Puntes. « Sculpting Windows onto AuAg Hollow Cubic Nanocrystals ». Nanomaterials 13, no 18 (19 septembre 2023) : 2590. http://dx.doi.org/10.3390/nano13182590.
Texte intégralRésumé :
Using surfactants in the galvanic replacement reaction (GRR) offers a versatile approach to modulating hollow metal nanocrystal (NC) morphology and composition. Among the various surfactants available, quaternary ammonium cationic surfactants are commonly utilised. However, understanding how they precisely influence morphological features, such as the size and void distribution, is still limited. In this study, we aim to uncover how adding different surfactants—CTAB, CTAC, CTApTS, and PVP—can fine-tune the morphological characteristics of AuAg hollow NCs synthesised via GRR at room temperature. Our findings reveal that the halide counterion in the surfactant significantly controls void formation within the hollow structure. When halogenated surfactants, such as CTAB or CTAC, are employed, multichambered opened nanoboxes are formed. In contrast, with non-halogenated CTApTS, single-walled closed nanoboxes with irregularly thick walls form. Furthermore, when PVP, a polymer surfactant, is utilised, changes in concentration lead to the production of well-defined single-walled closed nanoboxes. These observations highlight the role of surfactants in tailoring the morphology of hollow NCs synthesised through GRR.
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Petters, M. D., et S. M. Kreidenweis. « A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 3 : Including surfactant partitioning ». Atmospheric Chemistry and Physics 13, no 2 (28 janvier 2013) : 1081–91. http://dx.doi.org/10.5194/acp-13-1081-2013.
Texte intégralRésumé :
Abstract. Atmospheric particles can serve as cloud condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Köhler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of cloud condensation nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code.
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Khan, Iftheker A., Joseph R. V. Flora, A. R. M. Nabiul Afrooz, Nirupam Aich, P. Ariette Schierz, P. Lee Ferguson, Tara Sabo-Attwood et Navid B. Saleh. « Change in chirality of semiconducting single-walled carbon nanotubes can overcome anionic surfactant stabilisation : a systematic study of aggregation kinetics ». Environmental Chemistry 12, no 6 (2015) : 652. http://dx.doi.org/10.1071/en14176.
Texte intégralRésumé :
Environmental context Chirally enriched semiconducting single-walled carbon nanotubes (SWNTs) are some of the most utilised nanomaterials. Although chirality of SWNTs is known to influence their electronic properties and interfacial interaction, the interplay between chirality and surfactant structure in SWNT stability is not well understood. This study investigates these interactions, providing data to better assess the environmental fate of SWNTs. Abstract Single-walled carbon nanotubes’ (SWNT) effectiveness in applications is enhanced by debundling or stabilisation. Anionic surfactants are known to effectively stabilise SWNTs. However, the role of specific chirality on surfactant-stabilised SWNT aggregation has not been studied to date. The aggregation behaviour of chirally enriched (6,5) and (7,6) semiconducting SWNTs, functionalised with three anionic surfactants – sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sodium deoxycholate – was evaluated with time-resolved dynamic light scattering. A wide range of mono- (NaCl) and divalent (CaCl2) electrolytes as well as a 2.5mg total organic carbon (TOC) L–1 Suwannee River humic acid were used as background chemistry. Overall, sodium dodecyl benzene sulfonate showed the most effectiveness in stabilising SWNTs, followed by sodium deoxycholate and sodium dodecyl sulfate. However, the larger diameter (7,6) chirality tubes (compared to (6,5) diameter), compromised the surfactant stability due to enhanced van der Waals interaction. The presence of divalent electrolytes overshadowed the chirality effects and resulted in similar aggregation behaviour for both the SWNT samples. Molecular modelling results elucidated key differences in surfactant conformation on SWNT surfaces and identified interaction energy changes between the two chiralities to delineate aggregation mechanisms. The stability of SWNTs increased in the presence of Suwannee River humic acid under 10mM monovalent and mixed-electrolyte conditions. The results suggest that change in chirality can overcome surfactant stabilisation of semiconducting SWNTs. SWNT stability can also be strongly influenced by the anionic surfactant structure.
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Azum, Naved, Malik Abdul Rub, Anish Khan, Maha M. Alotaibi, Abdullah M. Asiri et Mohammed M. Rahman. « Mixed Micellization, Thermodynamic and Adsorption Behavior of Tetracaine Hydrochloride in the Presence of Cationic Gemini/Conventional Surfactants ». Gels 8, no 2 (17 février 2022) : 128. http://dx.doi.org/10.3390/gels8020128.
Texte intégralRésumé :
In this approach, tensiometry and UV-visible techniques are used to determine the effect of cationic gemini and conventional surfactants on tetracaine hydrochloride (TCH), an anesthetic drug. We have estimated micellar, interfacial, and energetic constraints. To gain a deep understanding of their mixed association behavior, the outputs were examined using different theoretical models. The critical micelle concentration for single and mixed amphiphiles was estimated. The cmc values of mixed amphiphiles were found between the individual amphiphiles due to strong attractive interaction (synergism) between the components after mixing. The non-ideal behavior of mixtures was confirmed by the larger values of ideal cmc than the experimental cmc values. The negative values of interaction parameter (β) and values of activity coefficients less than unity indicate strong synergistic interaction between drug and surfactant. The stability of the mixed systems is demonstrated by the negative Gibbs free energy of micellization and excess free energy of micellization. In contrast to a single chain surfactant, a double chain surfactant (gemini) exhibits better interactions with the drug. Spectral measurements (UV-visible spectra) were used to monitor the binding of the drug with surfactant (conventional as well as gemini). Studying these mixed aggregates could help to optimize their compositions and find synergistic properties between TCH monomers and surfactants.
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Zhao, Jun, Yenan Wang, Wenwen Dong, Yapan Wu, Dongsheng Li, Bin Liu et Qichun Zhang. « A new surfactant-introduction strategy for separating the pure single-phase of metal–organic frameworks ». Chemical Communications 51, no 46 (2015) : 9479–82. http://dx.doi.org/10.1039/c5cc02043c.
Texte intégralRésumé :
Surfactant-directed crystal growth can effectively separate mixed-phase crystals. By introducing different surfactants, two previous mixed-phase Ni(ii)–MOFs constructed from an undeveloped pyridyl-tetracarboxylate and Ni(ii) salts were successfully isolated to obtain two pure products.
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Lebrón, José Antonio, Pilar López-Cornejo, Elena García-Dionisio, Pablo Huertas, Margarita García-Calderón, María Luisa Moyá, Francisco José Ostos et Manuel López-López. « Cationic Single-Chained Surfactants with a Functional Group at the End of the Hydrophobic Tail DNA Compacting Efficiency ». Pharmaceutics 13, no 4 (20 avril 2021) : 589. http://dx.doi.org/10.3390/pharmaceutics13040589.
Texte intégralRésumé :
The interaction between calf-thymus DNA, ctDNA, and various single-chained surfactants with different functional groups at the end of hydrophobic tail was studied with the goal of investigating the influence of the functional group nature on surfactant DNA compacting efficiency. The surfactants investigated were dodecyltriethylammonium bromide (DTEABr), triethyl(1-phenoxydodecyl)ammonium bromide (12PhBr), triethyl(2-naphthoxydodecyl)ammonium bromide (12NBr) and 11-(isonicotinoyloxy)-N,N,N-triethyl-1-undecanaminium bromide (11PyBr). Results made evident that the surfactants’ tendencies to self-aggregation is the key factor determining their efficiency to compact the nucleic acid. Subsequently, DOPE/12NBr/pEGFP-C1 lipoplexes, with different cationic surfactant molar fractions (α) and mass ratios (L/D), were prepared and characterized. DOPE is a zwitterionic phospholipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine, and the plasmid pEGFP-C1 carries a GFP coding sequence with the necessary regulatory elements for constitutive expression of the gene in human cells. 12NBr was chosen because it was the most efficient DNA compacting agent among the surfactants investigated. Finally, the cytotoxicity and transfection efficiency (TE) of DOPE/12NBr/pDNA lipoplexes, with different compositions, were investigated.
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Attia, David, Evgenee Yekymov, Yulia Shmidov, Yael Levi-Kalisman, Orit Mendelson, Ronit Bitton et Rachel Yerushalmi-Rozen. « Surfactant-Mediated Co-Existence of Single-Walled Carbon Nanotube Networks and Cellulose Nanocrystal Mesophases ». Nanomaterials 11, no 11 (13 novembre 2021) : 3059. http://dx.doi.org/10.3390/nano11113059.
Texte intégralRésumé :
Hybrids comprising cellulose nanocrystals (CNCs) and percolated networks of single-walled carbon nanotubes (SWNTs) may serve for the casting of hybrid materials with improved optical, mechanical, electrical, and thermal properties. However, CNC-dispersed SWNTs are depleted from the chiral nematic (N*) phase and enrich the isotropic phase. Herein, we report that SWNTs dispersed by non-ionic surfactant or triblock copolymers are incorporated within the surfactant-mediated CNC mesophases. Small-angle X-ray measurements indicate that the nanostructure of the hybrid phases is only slightly modified by the presence of the surfactants, and the chiral nature of the N* phase is preserved. Cryo-TEM and Raman spectroscopy show that SWNTs networks with typical mesh size from hundreds of nanometers to microns are distributed equally between the two phases. We suggest that the adsorption of the surfactants or polymers mediates the interfacial interaction between the CNCs and SWNTs, enhancing the formation of co-existing meso-structures in the hybrid phases.
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Naranjo, E. « Phase behavior of cationic and anionic surfactants at low concentrations ». Proceedings, annual meeting, Electron Microscopy Society of America 50, no 1 (août 1992) : 694–95. http://dx.doi.org/10.1017/s0424820100123878.
Texte intégralRésumé :
Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.
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Yadav, Chandradip Kumar, Ajaya Bhattarai, Tulasi Prasad Niraula, Amar Prasad Yadav, Manoj Kumar Adhikari, Yog Prakash Yadav, Duryodhana Yadav et Sanjay Singh. « Critical Analysis of Surfactant-Dye Interaction : A Review ». Amrit Journal 3, no 1 (31 décembre 2023) : 66–77. http://dx.doi.org/10.3126/amritj.v3i1.61543.
Texte intégralRésumé :
The interaction between surfactants and dyes is fundamental in achieving the desired coloration and properties in various applications, shaping the functionality and effectiveness of dye-related processes across multiple industries. Further research and advancements in this field will continue contributing to innovative solutions and improved sustainability. While mixed surfactants offer these advantages, the choice between using a single surfactant or a mixture depends on the specific application, the desired properties, cost considerations, and compatibility with other formulation components. It's important to carefully evaluate the application requirements and conduct appropriate testing to determine the most effective approach. In this work, the physical-chemical characteristics and solubilization of reactive dyes in single and mixed micellar media are elaborated. Compared to the single-micellar medium, the mixed-micellar medium showed improved reactive dye trapping, which was attributed to the presence of both cationic and nonionic surfactants, namely cetyltrimethylammonium bromide (CTAB) and triton X-100. In this interactional study, two reactive dyes were used: Reactive Black 5 (RB) and Reactive Yellow 145 (RY). It is noteworthy to examine the modeling and micellization of mixed surfactant systems in an aqueous medium including dodecyl trimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS). The anionic-rich and cationic-rich interactions between methylene blue (MB) and methyl orange (MO) in aqueous solutions were clearly shown in the diagram.
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Bondar, M. Y., A. V. Osipov, A. A. Groman, I. N. Koltsov, G. Y. Scherbakov et O. V. Chebysheva. « The results of single well chemical tracer tests to assess the effectiveness of surfactant-polymer exposure at the Kholmogorskoye field ». Kazakhstan journal for oil & ; gas industry 4, no 2 (20 juillet 2022) : 101–11. http://dx.doi.org/10.54859/kjogi108466.
Texte intégralRésumé :
Methods of enhanced oil recovery in general and surfactant-polymer flooding in particular are considered as tertiary methods for the development of mature oil fields in Western Siberia, with the potential to increase oil recovery to 60-70% of the initial geological reserves.
To select an effective mixture of surfactants and polymer for surfactantpolymer flooding, laboratory tests were carried out in which the thermal stability, phase behaviour, interfacial tension and rheology of the formulations were tested. Filtration experiments were also carried out to optimize the volumes of injected fringes and the concentrations of reagents in them. At the final stage, single well chemical tracer tests (SWCTT) were carried out to assess the effectiveness of surfactant-polymer flooding on two wells of the Kholmogorskoye field. In order to investigate different technical and economic models of surfactant-polymer exposure, SWCTT tests were conducted with the same surfactant, but with a different design. The results of the SWCTT tests showed that the residual oil saturation in the affected area after injection of the surfactant-polymer solution decreased by about 11% compared to water flooding, which is about a third of the residual oil after flooding. The tested surfactant showed acceptable efficiency under suboptimal temperature conditions, which is favorable for the use of the selected surfactant-polymer composition for neighboring deposits and formations with different reservoir temperatures, but similar water composition.
In general, the results of the conducted field tests correlate with the results of the main laboratory experiments for the selected surfactant.
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Irish, B. M., J. C. Correll et T. E. Morelock. « The Effect of Synthetic Surfactants on Disease Severity of White Rust on Spinach ». Plant Disease 86, no 7 (juillet 2002) : 791–96. http://dx.doi.org/10.1094/pdis.2002.86.7.791.
Texte intégralRésumé :
White rust, caused by Albugo occidentalis, is an economically important disease of spinach (Spinacia oleracea). Although cultural practices and partial host resistance are used for disease management, control strategies often rely on fungicides. An alternative approach, the use of ionic (cationic or anionic) and nonionic surfactants, was evaluated for its effect on white rust in greenhouse and field experiments. Surfactant treatments were compared with a water control and two commercial fungicides, azoxystrobin (Quadris) and 1,2,3-benzothiadiazole-7-carbothioic acid S-methyl ester (Actigard). Greenhouse plants were treated with a single surfactant application followed by inoculation with sporangia. Disease severity was rated on leaves 8 to 12 days after inoculation. Field tests were conducted in Arkansas and Texas and received three to five surfactant applications during the season. Disease severity was determined at the end of the growing season. In greenhouse and field tests, all surfactant treatments showed significant reductions in white rust severity compared with water controls. The surfactants Naiad and sodium dodecyl sulfate (SDS) were highly effective and comparable to fungicides in reducing white rust severity. In a laboratory assay, microscopic examination revealed that most of the surfactants at low concentrations caused rapid (<2 min) zoospore lysis.
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McLachlan, Aleisha A., et D. Gerrard Marangoni. « 1D and 2D NMR investigations of the interaction between oppositely charged polymers and surfactants ». Canadian Journal of Chemistry 88, no 2 (février 2010) : 124–34. http://dx.doi.org/10.1139/v09-039.
Texte intégralRésumé :
Proton chemical shifts and two-dimensional COSY and NOE spectroscopy (NOESY) experiments have been used to examine the interaction of various oppositely charged surfactant and polyelectrolyte systems, namely, the cationic surfactant dodecyltrimethyammonium bromide (DTAB) and a series of alkanediyl-α,ω-bis(alkyldimethylammonium bromide) surfactants (Gem 12-s-12, where s is the length of the methylene spacer group) with the anionic polyelectrolyte poly(styrene sulfonate) or PSS. In all cases, we observe substantial aromatic-solute-induced chemical shifts (ASIS) in the surfactant peaks of the polymer/surfactant complexes versus that of the pure surfactant spectra. In the case of the DTAB/PSS system, the chemical-shift changes as a function of changing ratio of surfactant to polymer are interpreted in terms of structural changes that occur in the complex with increasing polymer concentration. For the Gem 12-s-12/PSS systems, the interaction of these gemini surfactants with the anionic polyelectrolyte, as deduced from the interpretation of the 1H ASIS shifts and the NOESY cross peaks, is dependent on the length of the methylene spacer. From the NOESY experiments, we observed significant NOESY cross peaks that correlated well with the expected mechanism of interaction as observed in the literature for the single-tailed surfactant/polymer system. NMR techniques are shown to provide information on the molecular arrangement of these molecules in aqueous solution.
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Kim, Gyeong-Seon, et Cho-Hi Park. « Research Trends of Natural and Natural-derived Surfactant in Raw Materials ». Journal of the Korean Society of Cosmetology 28, no 5 (31 octobre 2022) : 1124–34. http://dx.doi.org/10.52660/jksc.2022.28.5.1124.
Texte intégralRésumé :
This paper would like to identify the technological trends in the cosmetics market to analyze the efficacy and characteristics of natural and natural-derived surfactants in raw materials. The methods were investigated and analyzed in research and patents over the past decade at Riss and google scholar. Most of the natural surfactant from raw materials have been extracted using ethanol from green tea, soapberry, and Saponaria. Also, the isolated components of surfactant have been saponin as a wash. The natural-derived surfactant was exchanged and synthesized from raw materials such as soybeans, coconut, olives, etc. Moreover, the range of raw materials was expanded to amino acids and saccharides, and the utilization was expanded to oil, cleaning, and solubilization. The result of studies has shown that most of the natural surfactants of a single extract were as washes that the effect was limitations in the range of use or cannot be commercialized due to economic feasibility. However, composed of two or more types of extracts could increase the surfactant activity and the use of emulsion and solubilization could develop the possibility of use.
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Cao, Ya Feng, Mei Jun Qu, Feng Zhi Tan, Zhao Li Liu et Yuan Li. « Study on the Role of Surfactants to Aqueous Two-Phase Synthesizing CPAM ». Advanced Materials Research 781-784 (septembre 2013) : 511–14. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.511.
Texte intégralRésumé :
In this paper,cationic polyacrylamide (CPAM) was synthesized by using aqueous two-phase polymerization. The Role of surfactants to aqueous two-phase synthesizing CPAM was studied, including the effect of the type,the composition and the concentration of the surfactants. The results showed that non-ionic surfactants had a better stabilizing impact on the polymer aqueous two-phase system. And the effect of the compound surfactant was better than that of a single surfactant. Take the chemical compound of Tween80 and OP10 as the polymerization auxiliaries, the optimum reaction condition of synthesis were as follows:wTween80:ѡOP10=1.5,w=1.6%, 50°C.In this process conditions, the distribution coefficient was the most appropriate in the continuous phase, the total monomer conversion rate and the intrinsic viscosity number of the product reached the maximum.
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Li, Yanpeng, Tingting Zhu, Yanyan Liu, Ye Tian et Huanran Wang. « Effects of surfactant on bubble hydrodynamic behavior under flotation-related conditions in wastewater ». Water Science and Technology 65, no 6 (1 mars 2012) : 1060–66. http://dx.doi.org/10.2166/wst.2012.933.
Texte intégralRésumé :
Bubble behavior is fundamental to the performance of froth flotation operations used in wastewater treatment processes. To fully understand and characterize bubble behavior under flotation-related conditions in wastewater, the high-speed photographic method has been employed to examine the motion of single bubbles and size distribution of bubble swarms with intermediate sizes ranging from 1 to 4 mm in the presence of surfactants in a laboratory scale flotation column. Both distilled water and synthetic municipal wastewater have been used to make solutions as well as two types of common surfactants. The instantaneous bubble motion has been recorded by a high speed camera. Subsequently, bubble trajectory, dimensions, velocity and distribution have been determined from the recorded frames using the image analysis software. The experimental results show that the addition of surfactant into wastewater has similar effects on bubble hydrodynamic behavior as in pure water (e.g., improving trajectory stabilization, dampening bubble deformation, slowing down terminal velocity, reducing bubble size and increasing the specific surface area of bubble swarm) due to the Marangoni effect. However, it is interesting to note that surfactant effects on single bubble hydrodynamics in wastewater are slightly stronger than those in pure water while surfactant effects on size parameters of bubble swarms in wastewater are significantly stronger than those in pure water. This finding suggests that besides surfactant, inorganic salts present in synthetic wastewater have an important influence on bubble dispersion.
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&NA;. « Multiple vs single dose surfactant ». Inpharma Weekly &NA;, no 822 (février 1992) : 12. http://dx.doi.org/10.2165/00128413-199208220-00027.
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Jiao, Jinqing, Tao Li, Guangwen Zhang, Jing Xiong, Xuqing Lang, Xiaolong Quan, Yiwei Cheng et Yuechang Wei. « Molecular Dynamics Simulations of the Short-Chain Fluorocarbon Surfactant PFHXA and the Anionic Surfactant SDS at the Air/Water Interface ». Molecules 29, no 7 (3 avril 2024) : 1606. http://dx.doi.org/10.3390/molecules29071606.
Texte intégralRésumé :
The research and development of alternatives to long-chain fluorocarbon surfactants are desperately needed because they are extremely toxic, difficult to break down, seriously harm the environment, and limit the use of conventional aqueous film-forming foam fire extinguishing agents. In this study, mixed surfactant systems containing the short-chain fluorocarbon surfactant perfluorohexanoic acid (PFHXA) and the hydrocarbon surfactant sodium dodecyl sulfate (SDS) were investigated by molecular dynamics simulation to investigate the microscopic properties at the air/water interface at different molar ratios. Some representative parameters, such as surface tension, degree of order, density distribution, radial distribution function, number of hydrogen bonds, and solvent-accessible surface area, were calculated. Molecular dynamics simulations show that compared with a single type of surfactant, mixtures of surfactants provide superior performance in improving the interfacial properties of the gas–liquid interface. A dense monolayer film is formed by the strong synergistic impact of the two surfactants. Compared to the pure SDS system, the addition of PFHXA caused SDS to be more vertically oriented at the air/water interface with a reduced tilt angle, and a more ordered structure of the mixed surfactants was observed. Hydrogen bonding between SDS headgroups and water molecules is enhanced with the increasing PFHXA. The surface activity is arranged in the following order: PFHXA/SDS = 1:1 > PFHXA/SDS = 3:1 > PFHXA/SDS = 1:3. These results indicate that a degree of synergistic relationship exists between PFHXA and SDS at the air/water interface.
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Septiawan Adi Nugroho, Ilham Kuncahyo et Dian Marlina. « SCREENING OF PIROXICAM SELF-NANOEMULSIFYING DRUG DELIVERY SYSTEM (SNEDDS) USING FRACTIONAL FACTORIAL DESIGN ». Jurnal Kimia Riset 8, no 1 (13 juin 2023) : 69–80. http://dx.doi.org/10.20473/jkr.v8i1.43803.
Texte intégralRésumé :
Piroxicam belongs to BCS class II and has low solubility. Self-nanoemulsifying drug delivery systems (SNEDDS) are considered a potential approach for increasing the solubility and release of piroxicam. This study aimed to select the components and component ratios of piroxicam SNEDDS using fractional factorial design 26-2 (FFD). The variables used in the DFT development of piroxicam SNEDDS are the type and concentration of oil (triacetin and oleic acid), surfactant (kolliphor EL and Tween 60), and co-surfactants (Transcutol and PEG 400). The FFD results showed 16 runs with different proportions of the piroxicam SNEDDS components, which were then characterized by critical parameters including emulsification time, %transmittance, droplet size, and drug loading. The components and component ratios of the PKM SNEDDS were determined using single-factor plot analysis. The results showed that triacetin (oil), kolliphor EL (surfactant), Transcutol (co-surfactant) had the greatest contribution to the formation of piroxicam SNEDDS with an oil ratio range of 11.11–28.57%, surfactant 44.44–77.78%, co-surfactant 11.11–44.44 %.
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Weiss, William W., Xina Xie, Jason Weiss, Vishu Subramanian, Archie R. Taylor et Fred J. Edens. « Artificial Intelligence Used to Evaluate 23 Single-Well Surfactant-Soak Treatments ». SPE Reservoir Evaluation & ; Engineering 9, no 03 (1 juin 2006) : 209–16. http://dx.doi.org/10.2118/89457-pa.
Texte intégralRésumé :
Summary Following a series of laboratory imbibition-cell experiments, field tests were conducted to determine the effectiveness of surfactant-soak treatments as a single-well enhanced-oil-recovery (EOR) technique. The tests were conducted in the dolomite interval of the Phosphoria formation. Artificial intelligence was applied to analyze the mixed test results. The analysis suggested that the gamma ray log can be used to predict results and that a minimum amount of surfactant is required to improve production. Introduction Water imbibition as a recovery process was tested in the Spraberry field during the 1950s (Elkins and Skov 1962, 1963). This early work was followed by a test of the process in Cottonwood Creek field during the 1960s (Willingham and McCaleb 1967). Around the time of these field tests, a patent was issued (Graham et al. 1957) that suggested surfactants could enhance the imbibition recovery process. A later patent (Stone et al. 1970) implied that a Spraberry field test was designed, but results were not reported. Forty years later, researchers (Spindler et al. 2000; Standnes and Austad 2000; Chen et al. 2000) returned to the subject of wettability alteration. One description of a field test of the surfactant-soak process has been published (Chen et al. 2000). A great deal of effort was expended during the 1970s and 1980s in designing systems and field testing surfactant fluids with ultralow interfacial tensions (IFTs) as a flooding EOR process. Maintaining the integrity of the chemical slug from the injection well to the producing wells was fraught with problems. However, slug-integrity problems are diminished in single-well EOR applications. Recent laboratory work focused on the easily performed and interpreted imbibition-cell experiments. These experiments (with and without surfactants) and the reported success of pressure pulsing at Cottonwood Creek prompted further laboratory testing with reservoir rock and fluids (Xie 2002; Xie et al. 2004). This recent work indicated that a nonionic surfactant could substantially increase recovery from Phosphoria wells in the Cottonwood Creek field. The shallow-shelf carbonate reservoir is characterized as a steeply dipping, algal reef of the Phosphoria formation producing sour, 27°API, black oil from a dolomitized interval. Thickness of the dolomite varies from 20 to 100 ft. The average porosity is ~10% with ~1.0 md matrix permeability. The connate-water saturation is ~10%. Pan American Petroleum reported the low-pressure and low-temperature reservoir to be naturally fractured and oil-wet (Willingham and McCaleb 1967). Their description was based on laboratory core studies. Tests performed in the 1990s generated U.S. Bureau of Mines (USBM) wettability values of -0.1, -0.12, -0.18, and -0.26. The Cottonwood Creek field is located in the Bighorn basin of Wyoming, as shown in Fig. 1, and is operated by Continental Resources Inc.
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Kochkodan, Olga, et Viktor Maksin. « Mixed adsorption of hexadecylpyridinium bromide and Triton X surfactants at graphitized carbon black ». Journal of the Serbian Chemical Society 85, no 6 (2020) : 781–94. http://dx.doi.org/10.2298/jsc190416112k.
Texte intégralRésumé :
Adsorption of cationic 1-hexadecylpyridinium bromide (HDPB) and non-ionic p-(1,1,3,3-tetramethylbutyl)-phenoxypolyoxyethylene glycols surfactants of the Triton X series (Triton X-45, Triton X-100 and Triton X-305) from their single and mixed aqueous solutions at thermally graphitized carbon black (CB) was studied. It was shown that the adsorption of the non-ionic surfactant from its individual solution decreased when a number of ethylene oxide units in the surfactant molecule increased. Addition of the non-ionic surfactants increased the amount of HDPB adsorbed from HDPB/Triton X mixtures. At low solution concentrations it was found that in HDPB/Triton X mixtures, the experimental values of total surfactants adsorption are higher than the adsorption values calculated for the ideal surfactant mixtures. The composition of the mixed HDPB/Triton X adsorption layer and the parameters of the intermolecular interaction (?s), between the components in this layer, were calculated using the Rubingh-Rosen approach. It was shown that ?s parameters have negative values, which indicate notable interactions between Triton X molecules and HDPB ions in the mixed adsorption layer. It was found that the composition of the mixed adsorption layer at CB surface is notably different from the surfactants composition in the bulk solution. The mixed HDPB/Triton X adsorption layer is enriched with Triton X surfactant and the mole fraction of Triton X increases with decreasing of ethoxylation degree of its molecules.
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Leister, Nico, et Heike P. Karbstein. « Influence of Hydrophilic Surfactants on the W1–W2 Coalescence in Double Emulsion Systems Investigated by Single Droplet Experiments ». Colloids and Interfaces 5, no 2 (8 avril 2021) : 21. http://dx.doi.org/10.3390/colloids5020021.
Texte intégralRésumé :
Double emulsions are a promising formulation for encapsulation and targeted release in pharmaceutics, cosmetics and food. An inner water phase is dispersed in an oil phase, which is again emulsified in a second water phase. The encapsulated inner water phase can be released via diffusion or via coalescence, neither of which is desired during storage but might be intended during application. The two interfaces in a double emulsion are stabilized by a hydrophilic and a lipophilic surfactant, to prevent the coalescence of the outer and the inner emulsion, respectively. This study focuses on the influence of the hydrophilic surfactant on the release of inner water or actives encapsulated therein via coalescence of the inner water droplet with the outer O–W2 interface. Since coalescence and diffusion are difficult to distinguish in double emulsions, single-droplet experiments were used to quantify differences in the stability of inner droplets. Different lipophilic (PGPH and PEG-30 dipolyhydroxylstearate) and hydrophilic surfactants (ethoxylates, SDS and polymeric) were used and resulted in huge differences in stability. A drastic decrease in stability was found for some combinations, while other combinations resulted in inner droplets that could withstand coalescence longer. The destabilization effect of some hydrophilic surfactants depended on their concentration, but was still present at very low concentrations. A huge spread of the coalescence time for multiple determinations was observed for all formulations and the necessary statistical analysis is discussed in this work. The measured stabilities of single droplets are in good accordance with the stability of double emulsions for similar surfactant combinations found in literature. Therefore, single droplet experiments are suggested for a fast evaluation of potentially suitable surfactant combinations for future studies on double-emulsion stability.
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Stamps, Robert H. « 547 Effects of Media Surfactants on Growth and Postharvest Dessication of Impatiens, Petunia, and Spathiphyllum ». HortScience 34, no 3 (juin 1999) : 540C—540. http://dx.doi.org/10.21273/hortsci.34.3.540c.
Texte intégralRésumé :
Impatiens `Dazzler Violet', Petunia × hybrida `Carpet Blue', and Spathiphyllum `Ty's Pride' plugs were planted in 10-cm pots containing a commercial peat-based soilless growing medium composed of Canadian 60 peat: 20 vermiculite: 20 perlite (by vol) not treated with surfactant. Growing medium was treated, or not treated, 1) at planting, 2) during production, and/or 3) preshipment with experimental surfactants. The production phase consisted of growing plants on raised benches in a greenhouse until they reached marketable size. Phytotoxicity, plant water use and growth were determined. At the beginning of the postproduction phase, growing medium in all pots was brought to container capacity. Plants were then dried to wilting three times. Water loss and water retained on rewatering and times to wilt and recovery were recorded. Surfactant treatments caused no foliar phytotoxicity and did not delay flowering for petunia or spathiphyllum. However, surfactant treatments delayed flowering for impatiens by ≈4 days. Surfactant treatments increased top growth of petunia but not of the other crops. Postproduction, water retention at rewatering, and times to wilt were increased for petunia and spathiphyllum when they were in surfactant-treated medium. For impatiens, treatments had no effects on water retention or wilting, probably due to the small root systems and limited attendant medium dewatering for this crop. Generally, all three experimental surfactants performed similarly and weekly and preshipment surfactant applications were of no additional benefit compared to a single initial application at planting.
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Ahmadi, Delaram, Najet Mahmoudi, Richard K. Heenan, David J. Barlow et M. Jayne Lawrence. « The Influence of Co-Surfactants on Lamellar Liquid Crystal Structures Formed in Creams ». Pharmaceutics 12, no 9 (11 septembre 2020) : 864. http://dx.doi.org/10.3390/pharmaceutics12090864.
Texte intégralRésumé :
It is well-established that oil-in-water creams can be stabilised through the formation of lamellar liquid crystal structures in the continuous phase, achieved by adding (emulsifier) mixtures comprising surfactant(s) combined (of necessity) with one or more co-surfactants. There is little molecular-level understanding, however, of how the microstructure of a cream is modulated by changes in co-surfactant and of the ramifications of such changes on cream properties. We investigate here the molecular architectures of oil-free, ternary formulations of water and emulsifiers comprising sodium dodecyl sulfate and one or both of the co-surfactants hexadecanol and octadecanol, using microscopy, small-angle and wide-angle X-ray scattering and small-angle neutron scattering. We then deploy these techniques to determine how the structures of the systems change when liquid paraffin oil is added to convert them to creams, and establish how the structure, rheology, and stability of the creams is modified by changing the co-surfactant. The ternary systems and their corresponding creams are shown to contain co-surfactant lamellae that are subtly different and exhibit different thermotropic behaviours. The lamellae within the creams and the layers surrounding their oil droplets are shown to vary with co-surfactant chain length. Those containing a single fatty alcohol co-surfactant are found to contain crystallites, and by comparison with the cream containing both alcohols suffer adverse changes in their rheology and stability.
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Maynard-Benson, Amber, Mariya Alekisch, Alyssa Wall, Eugene J. Billiot, Fereshteh H. Billiot et Kevin F. Morris. « Characterization of Micelle Formation by the Single Amino Acid-Based Surfactants Undecanoic L-Isoleucine and Undecanoic L-Norleucine in the Presence of Diamine Counterions with Varying Chain Lengths ». Colloids and Interfaces 7, no 2 (4 avril 2023) : 28. http://dx.doi.org/10.3390/colloids7020028.
Texte intégralRésumé :
The binding of linear diamine counterions with different methylene chain lengths to the amino-acid-based surfactants undecanoic L-isoleucine (und-IL) and undecanoic L-norleucine (und-NL) was investigated with NMR spectroscopy. The counterions studied were 1,2-ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, and 1,6-diaminohexane. These counterions were all linear diamines with varying spacer chain lengths between the two amine functional groups. The sodium counterion was studied as well. Results showed that when the length of the counterion methylene chain was increased, the surfactants’ critical micelle concentrations (CMC) decreased. This decrease was attributed to diamines with longer methylene chains binding to multiple surfactant monomers below the CMC and thus acting as templating agents for the formation of micelles. The entropic hydrophobic effect and differences in diamine counterion charge also contributed to the size of the micelles and the surfactants’ CMCs in the solution. NMR diffusion measurements showed that the micelles formed by both surfactants were largest when 1,4-diaminobutane counterions were present in the solution. This amine also had the largest mole fraction of micelle-bound counterions. Finally, the und-NL micelles were larger than the und-IL micelles when 1,4-diaminobutane counterions were bound to the micelle surface. A model was proposed in which this surfactant formed non-spherical aggregates with both the surfactant molecules’ hydrocarbon chains and n-butyl amino acid side chains pointing toward the micelle core. The und-IL micelles, in contrast, were smaller and likely spherically shaped.
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Loglio, Giuseppe, Volodymyr I. Kovalchuk, Alexey G. Bykov, Michele Ferrari, Jürgen Krägel, Libero Liggieri, Reinhard Miller et al. « Interfacial Dilational Viscoelasticity of Adsorption Layers at the Hydrocarbon/Water Interface : The Fractional Maxwell Model ». Colloids and Interfaces 3, no 4 (10 décembre 2019) : 66. http://dx.doi.org/10.3390/colloids3040066.
Texte intégralRésumé :
In this communication, the single element version of the fractional Maxwell model (single-FMM or Scott–Blair model) is adopted to quantify the observed behavior of the linear interfacial dilational viscoelasticity. This mathematical tool is applied to the results obtained by capillary pressure experiments under low-gravity conditions aboard the International Space Station, for adsorption layers at the hydrocarbon/water interface. Two specific experimental sets of steady-state harmonic oscillations of interfacial area are reported, respectively: a drop of pure water into a Span-80 surfactant/paraffin-oil matrix and a pure n-hexane drop into a C13DMPO/TTAB mixed surfactants/aqueous-solution matrix. The fractional constitutive single-FMM is demonstrated to embrace the standard Maxwell model (MM) and the Lucassen–van-den-Tempel model (L–vdT), as particular cases. The single-FMM adequately fits the Span-80/paraffin-oil observed results, correctly predicting the frequency dependence of the complex viscoelastic modulus and the inherent phase-shift angle. In contrast, the single-FMM appears as a scarcely adequate tool to fit the observed behavior of the mixed-adsorption surfactants for the C13DMPO/TTAB/aqueous solution matrix (despite the single-FMM satisfactorily comparing to the phenomenology of the sole complex viscoelastic modulus). Further speculations are envisaged in order to devise combined FMM as rational guidance to interpret the properties and the interfacial structure of complex mixed surfactant adsorption systems.
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Sakač, Nikola, Dubravka Madunić-Čačić, Dean Marković et Marija Jozanović. « Study of Cationic Surfactants Raw Materials for COVID-19 Disinfecting Formulations by Potentiometric Surfactant Sensor ». Sensors 23, no 4 (13 février 2023) : 2126. http://dx.doi.org/10.3390/s23042126.
Texte intégralRésumé :
The behavior of a new 1,3-dioctadecyl-1H-imidazol-3-ium tetraphenylborate (DODI-TPB) surfactant sensor was studied in single and complex mixtures of technical grade QACs—benzalkonium chloride (BAC), N,N-didecyl-N,N-dimethylammonium chloride (DDAC), and N,N-dioctyl-N,N-dimethylammonium chloride (DOAC) usually used in COVID-19 disinfecting agents formulations. The results obtained with the new DODI-TPB sensor were in good agreement with data measured by a 1,3-dihexadecyl−1H-benzo[d]imidazol−3-ium-tetraphenylborate (DMI-TPB) surfactant sensor, as well as two-phase titration used as a reference method. The quantitative titrations of a two-component mixture of the cationic homologs (a) DDAC and DOAC; and (b) BAC and DOAC showed that the new DODI-TPB surfactant sensor can clearly distinguish two separate mixture components in a single potentiometric titration curve with two characteristic inflexion points. The consumption of SDS (used as a titrant) in the end-point 1 (EP 1) corresponded to the content of DDAC (or BAC), whereas the consumption in the end-point 2 (EP 2) corresponded to the total content of both cationic surfactants in the mixture. DOAC content in both mixtures can be calculated from the difference of the titrant used to achieve EP1 and EP2. The addition of nonionic surfactants resulted in the signal change decrease from 333.2 mV (1:0; no nonionic surfactant added) to 243.0 mV (1:10, w/w). The sensor was successfully tested in ten two-component COVID-19 disinfecting formulations.
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Vasilieva, Elmira A., Darya A. Kuznetsova, Farida G. Valeeva, Denis M. Kuznetsov et Lucia Ya Zakharova. « Role of Polyanions and Surfactant Head Group in the Formation of Polymer–Colloid Nanocontainers ». Nanomaterials 13, no 6 (16 mars 2023) : 1072. http://dx.doi.org/10.3390/nano13061072.
Texte intégralRésumé :
Objectives. This study was aimed at the investigation of the supramolecular systems based on cationic surfactants bearing cyclic head groups (imidazolium and pyrrolidinium) and polyanions (polyacrylic acid (PAA) and human serum albumin (HSA)), and factors governing their structural behavior to create functional nanosystems with controlled properties. Research hypothesis. Mixed PE–surfactant complexes based on oppositely charged species are characterized by multifactor behavior strongly affected by the nature of both components. It was expected that the transition from a single surfactant solution to an admixture with PE might provide synergetic effects on structural characteristics and functional activity. To test this assumption, the concentration thresholds of aggregation, dimensional and charge characteristics, and solubilization capacity of amphiphiles in the presence of PEs have been determined by tensiometry, fluorescence and UV-visible spectroscopy, and dynamic and electrophoretic light scattering. Results. The formation of mixed surfactant–PAA aggregates with a hydrodynamic diameter of 100–180 nm has been shown. Polyanion additives led to a decrease in the critical micelle concentration of surfactants by two orders of magnitude (from 1 mM to 0.01 mM). A gradual increase in the zeta potential of HAS–surfactant systems from negative to positive value indicates that the electrostatic mechanism contributes to the binding of components. Additionally, 3D and conventional fluorescence spectroscopy showed that imidazolium surfactant had little effect on HSA conformation, and component binding occurs due to hydrogen bonding and Van der Waals interactions through the tryptophan amino acid residue of the protein. Surfactant–polyanion nanostructures improve the solubility of lipophilic medicines such as Warfarin, Amphotericin B, and Meloxicam. Perspectives. Surfactant–PE composition demonstrated beneficial solubilization activity and can be recommended for the construction of nanocontainers for hydrophobic drugs, with their efficacy tuned by the variation in surfactant head group and the nature of polyanions.