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41.
The conditions to obtain W/0 microemulsions using ionic surfactants and a nonionic cosurfactant, a polyoxyethylene alkyl ether, were investigated. The length of the polyoxyethylene chain was critical to obtain the typical water solubilization maximum The variation of the W/0 microemulsion region with hydrocarbon content was different from that of the usual type of microemulsions having a medium chain length alcohol as cosurfactant. In the present systems the W/0 microemulsion region was not a direct continuation of the inverse micellar area at zero content of hydrocarbon. Addition of hydrocarbon was necessary for the formation of inverse micelles The microemulsion regions were sensitive to the kind of hydrocarbon used; a sign of the importance of the nonionic surfactant for the stability of this kind of microemulsions. 相似文献
42.
Ibrahim Kayali Fang Li Zhiqiang Zhang Joel D. Sandburg Stig E. Friberg Patricia A. Aikens 《Journal of Dispersion Science and Technology》2013,34(7):1789-1807
Copolymerization of sodium acrylamidostearate (NaAAS) and oleic acid was performed in the lamellar liquid crystal (LLC) formed by NaAAS, oleic acid and water, in the absence of N.N’-methylenebisacrylamide (MBAA) and in the presence of MBAA, respectively. In the absence of MBAA, after the polymerization the lamellar structure remained, and the disorder of the lamellar liquid crystal was, to some extent, enhanced. Surface tension, small-angle X-ray diffraction, viscosity, and fluorescence methods were used to study the properties of the linear copolymer. The linear polymeric surfactant behaves like 相似文献
43.
Jochen Beyermann Joachim Kötz Werner Jaeger Stig E. Friberg 《Journal of Dispersion Science and Technology》2013,34(7):1809-1820
The influence of different amounts of anionic copolymers of N-Methyl N-vinyl acetamide (NMVA) and acrylic acid with various charge densities on the formation of the lamellar liquid crystal formed by sodium dodecyl sulfate (SDS)/decanol/water was investigated by means of polarization microscopy, small angle x-ray scattering (SAXS), transmission electron microscopy and rheology. On the contrary to the incorporation of poly(acrylic acid) 相似文献
44.
Stig E. Friberg Lingling Ge Rong Guo 《Journal of Dispersion Science and Technology》2013,34(5):735-739
A model is presented to provide quantitative measures to estimate the trends of the change in the penetration of the added component into the polar part of the amphiphile layer in lamellar liquid crystals of water and ethoxylated surfactants with added water (or polar solvents). The total thickness of the bi‐layer is treated as composed of an aqueous layer, of a layer of the polar groups from the surfactant and of the hydrocarbon chains of the latter. A fraction α of the added water is assumed penetrating the polar group layer leading to its expansion. The evaluation is built on the fact that experimental determinations of the interlayer spacing in the overwhelming majority of cases show a first order linear dependence on the ratio of added water. In the model this linearity is obtained by variation of the degree of penetration of water. The model indicated a reduction in the degree of penetration with added water, which is a rational trend. The model demonstrates the earlier interpretation of a structure, whose interlayer spacing is invariant with water contents as nonswelling; for example, in which all added water penetrates the amhiphile layer, is not appropriate. The model demonstrates the constancy of the interlayer spacing to be a consequence of a balance between the expansion of the amphiphile layer and the increase of a “free water” layer. 相似文献
45.
The structure and action of hydrotropes are discussed using surfactant association structures as a model. The main action of a hydrotrope is to prevent phase separation from an aqueous solution; either by disordering of a lamellar liquid crystal or by preventing the formation of well defined normal and inverse micelles. 相似文献
46.
Ayat A. Bozeya Abeer F. Al-Bawab Stig E. Friberg Lingling Ge Guo Rong 《Colloid and polymer science》2013,291(8):1933-1938
The system water–benzene–ethanol was used to illustrate the complexity of spontaneous emulsification, when water-poor emulsions are brought in contact with water. In the first case, an O/W emulsion located close to the plait point in the system was used. The aqueous phase in the emulsion was incompatible with water, and a strong spontaneous emulsification to an O/W between the two liquids took place in the water layer close to the interface between layers. In the second case, a W/O emulsion, also close to the plait point, was brought in contact with water. Now, the spontaneous emulsification between the water and the oil phase of the original emulsion to an O/W emulsion also took place in the water layer forming a distinct emulsion layer beneath the interface. 相似文献
47.
Silas Arandas Monteiro e Silva Michele Fernanda Costa Valarini Marlus Chorilli Stig E. Friberg 《Journal of Dispersion Science and Technology》2014,35(8):1191-1199
Formulations with lyotropic liquid crystals were prepared from a Brazilian nut vegetable oil, guarana extract and combination of sorbitan monooleate (Span 80) and sorbitan monolaurate ethoxylate EO 20 (Tween 20) in the ratio 1:3 (surfactant component) and their physical–chemical aspects and rheological properties were determined. Compositions with liquid crystals were found in the pseudoternary diagram in a surfactant range of 70–90% and polarized light microscopy, small-angle x-ray scattering (SAXS) showed them to be lamellar. The preparations were furthermore characterized rheologically by shear stress shear rate sweeps finding plastic and pseudoplastic behavior without thixotropy. Electric conductivity and pH measurements demonstrated a potential for future application as dermatological delivery system of the active compounds in the Bertholletia excelsa and Paullinia cupana. 相似文献
48.
Helene?Bonkerud?Dugstad Nickolaj?Jacob?PetersenEmail author Henrik?Jensen Charlotte?Gabel-Jensen Steen?Honoré?Hansen Stig?Pedersen-Bjergaard 《Analytical and bioanalytical chemistry》2014,406(2):421-429
A small and very simple electromembrane extraction probe (EME-probe) was developed and coupled directly to electrospray ionization mass spectrometry (ESI-MS), and this system was used to monitor in real time in vitro metabolism by rat liver microsomes of drug substances from a small reaction (incubation) chamber (37 °C). The drug-related substances were continuously extracted from the 1.0 mL metabolic reaction mixture and into the EME-probe by an electrical potential of 2.5 V. The extraction probe consisted of a 1-mm long and 350-μm ID thin supported liquid membrane (SLM) of 2-nitrophenyl octyl ether. The drugs and formed metabolites where extracted through the SLM and directly into a 3 μL min?1 flow of 60 mM HCOOH inside the probe serving as the acceptor solution. The acceptor solution was directed into the ESI-MS-system, and the MS continuously monitored the drug-related substances extracted by the EME-probe. The extraction efficiency of the EME-probe was dependant on the applied electrical potential and the length of the SLM, and these parameters as well as the volume of the reaction chamber were set to the values mentioned above to avoid serious depletion from the reaction chamber (soft extraction). Soft extraction was mandatory in order not to affect the reaction kinetics by sample composition changes induced by the EME-probe. The EME-probe/MS-system was used to establish kinetic profiles for the in vitro metabolism of promethazine, amitriptyline and imipramine as model substances. 相似文献
49.
Rachek IA Barkov LM Belostotsky SL Dmitriev VF Dyug MV Gilman R Holt RJ Lazarenko BA Mishnev SI Nelyubin VV Nikolenko DM Osipov AV Potterveld DH Sadykov RSh Shestakov YV Stibunov VN Toporkov DK de Vries H Zevakov SA 《Physical review letters》2007,98(18):182303
A new accurate measurement of the tensor analyzing powers T20, T21, and T22 in deuteron photodisintegration has been performed. Wide-aperture nonmagnetic detectors allowed broad kinematic coverage in a single set up: E(gamma)=25 to 600 MeV, and theta(p)(cm)=24 degrees to 48 degrees and 70 degrees to 102 degrees . The new data provide a significant improvement over the few existing measurements. The angular dependency of the tensor asymmetries in deuteron photodisintegration is extracted for the first time. 相似文献
50.
Jiang X Arrington J Benmokhtar F Camsonne A Chen JP Choi S Chudakov E Cusanno F Deur A Dutta D Garibaldi F Gaskell D Gayou O Gilman R Glashauser C Hamilton D Hansen O Higinbotham DW Holt RJ de Jager CW Jones MK Kaufman LJ Kinney ER Kramer K Lagamba L de Leo R Lerose J Lhuillier D Lindgren R Liyanage N McCormick K Meziani ZE Michaels R Moffit B Monaghan P Nanda S Paschke KD Perdrisat CF Punjabi V Qattan IA Ransome RD Reimer PE Reitz B Saha A Schulte EC Sheyor R Slifer K Solvignon P Sulkosky V 《Physical review letters》2007,98(18):182302
We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance. 相似文献