Tween 20 system

Figure. 8.8 Comparison of high resolution AFM images of Langmuir-Blodgett films obtained from the air-water interface for three protein + Tween 20 systems (A) p-casein, 0.6 x 0.6 pm, surface pressure % = 20.6 mN/m (B) p-lactoglobulin, 0.8 x 0.8 pm, % = 26.1 mN/m (C) a-lact-albumin, 0.7 x 0.7 pm, % = 28.4 mN/m. Reproduced from Mackie et al (1999b) with permission.

The surface rheological properties of the /3-lg/Tween 20 system at the macroscopic a/w interface were examined by a third method, namely surface dilation [40]. Sample data obtained are presented in Figure 24. The surface dilational modulus, (E) of a liquid is the ratio between the small change in surface tension (Ay) and the small change in surface area (AlnA). The surface dilational modulus is a complex quantity. The real part of the modulus is the storage modulus, e (often referred to as the surface dilational elasticity, Ed). The imaginary part is the loss modulus, e , which is related to the product of the surface dilational viscosity and the radial frequency ( jdu). 

Experiments with the /3-lg/Tween 20 system were performed at a macroscopic a/w interface at a /3-lg concentration of 0.2 mg/ml [40]. The data obtained relate to the properties of the interface 20 minutes after formation. Up to R = 1, the storage modulus (dilational elasticity) was large and relatively constant, whereas the loss modulus (dilational viscosity) increased with increasing R. As R was increased to higher values there was a marked decrease in the storage modulus (dilational elasticity) and a gradual increase in the loss modulus (dilational viscosity). In summary, the data show the presence of a transition in surface dilational behavior in this system at a solution composition of approximately R = 1. At this point, there is a transformation in the adsorbed layer properties from elastic to viscous. 

Hydrophobic [bmim][PFg] was also used to replace typical organic solvents in ternary systems [27, 37, 38]. Gao et al. prepared and characterized water-[bmim] [PF ]-TX-100 [27] as well as water-[bmim][PFJ-Tween-20 systems [39]. For the former, they identified three different phases by using cyclic voltammetry [27] water-in-[bmim][PF ] droplets, bicontinuous structures, and [bmim][PF ]-in-water droplets. In recent studies, Seth et al. also prepared water-[bmim][PF ]- IX-100 and studied the interaction of [bmim][PF ] with water [37,38]. 

Concerning the stability of foams formed by mixed systems, it can be seen in Figure 10.3 that the surfactant affects very differently the stability of the foams formed by whole casein and P-casein, respectively. On the one hand, the stability of foam of P-casein/Tween 20 system decreases monotonously with increasing concentration of surfactant. This continues until practically reaching the... 

Contrary to the case of P-casein/Tween 20 systans, although the surface pressure isotherms shed some light on the surface structure of whole casein/Tween 20 systems, the information extracted does not provide a full explanation to the behavior of foams stabilized by this system. Taking into account the key information provided by the confinement in thin liquid films as regards the foam stability of whole casein and P-casein solutions, which was examined in the previous section, let us evaluate the properties of the foam films stabilized with whole casein/Tween 20 mixtures. Table 10.2 shows the thickness of foam films stabilized by pure whole casein, pure Tween 20 and two mixed systems under similar conditions to the foam stability, and the surface pressure experiments. The film thickness is measured by using Scheludko s microinterferometric method (Maldonado-Valderrama and Langevin, 2008). 

A mixture of 70% Tween 60 and 30% Span 65 gives optimum behavior in a given emulsion system. What composition mixture of sodium lauryl sulfate and cetyl alcohol should also give optimum behavior in the same system ... 

Dou ble hel ix (Section 28 8) The form in which DNA normally occurs in living systems Two complementary strands of DNA are associated with each other by hydrogen bonds be tween their base pairs and each DNA strand adopts a helical shape... 

For systems with more than two subsystems the beta-factor model, as presented, does not a I - tween different numbers of multiple failures. This siraplificat i... 

The ingredients are nonionic surfactants. It is their application as amine replacements in steam-condensate systems that is novel, not the raw materials. These products are commonly found in skin and hair products and in cosmetics because of their mildness and their excellence as water-in-oil emulsifiers and co-emulsifiers in oil-in-water emulsions. Raw material brands include Tween (ICI, PLC), Crill , and Crillet (Croda PLC). 

A mimic system of a photosynthetic apparatus was realized by solubihzing C-phy-cocyanin and zinc phthalocyanine in reversed micelles of tween-80 dispersed in cyclohexane [63]. 

In this in vitro system, the presence of serum in cell culture medium is not necessary, but the type of transwell is important (the total amount of H-triglycerides secreted was two-fold higher when using 3 pm versus 1 pm pore size transwells), and oleic acid supplementation is required for the formation and secretion of CMs as well as the transport of 3-carotene through Caco-2 cells. Finally, the presence of Tween 40 does not affect CM synthesis and secretion in this in vitro cell culture system. Thus, CMs secreted by Caco-2 cells were characterized as particles rich in newly synthesized H-triglycerides (90% of total secreted) containing apolipoprotein B (30% of total secreted) and H-phospholipids (20% of total secreted) and with an average diameter of 60 nm. These characteristics are close to those of CMs secreted in vivo by enterocytes. ... 

The common concentration of a surfactant used in a formulation varies from 0.05 to 0.5% and depends on the surfactant type and the solids content of the dispersion. In practice, very often combinations of surfactants rather than single agents are used to prepare and stabilize disperse systems. The combination of a more hydrophilic surfactant with a more hydrophobic surfactant leads to the formation of a complex film at the interface. A good example for such a surfactant pair is the Tween-Span system of Atlas-ICI [71]. 

Thus, in contrast to previous in vivo models, this in vitro model provides the possibility of dissociating experimentally two important processes of the intestinal carotenoid absorption cellular uptake and secretion. Under conditions mimicking the postprandial state (TC OA supplementation), differentiated Caco-2 cells were able (1) to take up carotenoids at the apical side and to incorporate them into CM and (2) to secrete them at the basolateral side, associated with CM fractions. In this model, no attempt has yet been made to reproduce the in vivo physiochemical conditions occurring in the intestinal lumen, such as carotenoid release from the food matrix and solubilization into mixed lipid micelles. Carotenoids were delivered to Caco-2 cells in aqueous suspension with Tween 40 (During et al., 2002). Using this cell culture system in conjunction with an in vitro... 

Solubility/miscibility Generally very soluble or miscible in water. Soluble in ethanol, com oil, and olive oil. Insoluble in mineral oil Biological considerations Surfactant. May cause micelle formation, with incumbent effects on bioavailability if included at concentrations of 1% or higher. May be associated with irritation if given intravenously or intramuscularly. Dogs have the peculiarity that Tweens injected parenterally induce the spontaneous systemic release of histamine. This response is particularly striking with IV injection, and therefore Tweens should not be used as components of IV vehicles in dogs... 

Different food components (e.g., fruit extracts) and commonly used pharmaceutical excipients (e.g., Tween 80) can interfere with secretory transport systems, leading to drug-food interactions [31, 43, 46, 167], As for CYPs, inhibition and induction of efflux transporters have been reported as possible... 

Extraction of the cellulase system. The culture of SSF from each flask (originally 5 g of substrate) was mixed well with more water to bring the final weight of the mixture (mycelium plus unutilized lignin, cellulose, and hemicelluloses) to 100 g. Tween 80 was added at a rate of 0.1%. The mixture was shaken for 0.5 h and centrifuged. The supernatant was used for enzyme determination. We estimated that about 7% to 10% cellulases remained adsorbed on the residues (mycelium and unutilized cellulose, hemicelluloses, and lignin) when the residues were suspended in water and Tween 80 as before and the supernatant was tested for cellulase titer. 

In the case of the piezo system, biotinylated antibodies were dispensed at 1 nL to produce spot diameters of 230 p on avidin-coated glass slides (NeutrAvidin , Pierce). The concentration of biotinylated antibody (Cy5-labeled mouse IgG) was varied from 2.5 to 20 pg/mL, while the ionic strength varied by dilution of PBS (10 mM to 150 mM, where 150 mM = 137 mM NaCl, 3 mM KCl, and 10 mM phosphate, pH 7.4) in distilled water. BSA was added as a carrier protein at 0.1% (w/v). After printing, the slides were rinsed in 150 mM PBS containing 0.05% Tween-20 (PBST), followed by distilled water and dried under a nitrogen stream. 

Fig. 10 relates the composite extraction index (see above) obtained in the low-shear aqueous test system for these Tween surfactants, and adhesion tensions measured against various solids. Adhesion tensions against platinum and bitumen saturated pyrophyllite are irregularly related to tar sand extraction, while the adhesion tension against a fresh pyrophyllite surface is linearly (inversely) related to tar sand extraction. This is the first linear correlation between a measurable property of a surfactant solution and tar sand extraction which we have been able to obtain, and there appears to be no such finding in the literature. Fig. 11 gives the relations between extraction of bitumen with the paddle mill, solvent-aqueous-surfactant extraction and adhesion tensions measured against platinum, bitumen saturated pyrophyllite and hydrated (48 hours in water) pyrophyllite. 

Fig. 4 Electropherogram of cephalosorins (1—cefpim, 2—cefpirom, 3—cepha-loridin, 4—cephlexin, 5—cefaclor, 6—cefuroxim, 7—cefotaxin) in a microemulsion system. Buffer, pH 7.0, 10 mM phosphate containing 6.49% l-butanol/0.82% ra-heptane, 1.44% glycodeoxycholic acid (GDC), and 5.685% Tween. Capillary, 48.5- (40 cm to detector) X 50-/rm ID 30 kV detection, 265 nm. (From Ref. 14.)...

Figure 7 indicates the phase behavior of SOW systems containing ternary nonionic surfactant mixtures that in turn contain a very hydrophilic surfactant (Tween 60 Sorbitan -i- 20 EO stearate), a very hpophihc surfactant (Span 20 Sorbitan monolaurate), and an intermediate (Tween 85 Sorbitan 20 EO trioleate or Nonylphenol with an average of 5 EO groups). The two intermediate surfactants correspond exactly to an optimum formulation in the physicochemical conditions, i.e., they exhibit three-phase behavior with the system 1 wt. % NaCl brine-heptane-2-butanol. As the intermediate hy-drophihcity surfactant is replaced by an equivalent mixture of the extreme ... 

Different shapes of CdS nanomaterials such as quasi-nanospheres, nanoshuttles and nanotubes have been prepared in the w/o microemulsion system of nonionic surfactant (Tween-80, polyetheneoxy(20)octadecyl ether, polyoxyethylele(9)dodecyl ether (C12E9) or Tx-100)/ -pentanol/aqueous so-lution/cyclohexane [191]. Another kind of QDs, PbS, have also been prepared in nonionic CnEg/water/cyclohexane microemuisions [192]. 

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