Pluronics determination

In view of the importance of the particle/bubble contact, it may be assumed that the stress acting on the particles during gas sparging is determined by electrostatic interactions as well as by hydrophobic and hydrophilic interactions, which are determined by the nature of the liquid/solid system. The use of Pluronic as additive leads to the reduction of destruction process [44,47] possibly due to less bubble/floc contact which is also described by Meier et. al. [67]. 

A device designed to determine the transport of an epidermal growth factor from a Pluronic gel, a Carbopol gel, and a vanishing cream base was shown capable of demonstrating formulation-dependent release kinetics [22], This device consists of a release cell which has a membrane to minimize release due to mechanical breakdown and is placed in a stirred and temperature-controlled receptor fluid. 

Domingo et al. evaluated immobilization of trichloroethylene-degrading Burkholderia cepacia bacteria using hydrophilic polyurethane foam. The influences of several foam formulation parameters upon cell retention were examined. Surfactant type was a major determinant of retention a lecithin-based compound retained more cells than Pluronic- or silicone-based surfactants. 

Field gradient NMR has been employed to determine the self-diffusion coefficient of a Pluronic triblock, and the hydrodynamic radius has been compared to DLS measurements on the same system (Almgren et al. 1992). NMR was found to give a somewhat lower value for the hydrodynamic radius than DLS. However, at infinite dilution the values obtained from the two techniques are the same. A similar observation has been made for eye I o - PB027P H 0,44 in aqueous solution (Yu et al. 1996c). Tin s effect has been attributed (Almgren et al. 1995) to the difference in dynamic averaging for the DLS and NMR experiments. In DLS,... 

Fig. 4.13 (a) Phase diagram for aqueous solutions of Pluronic 25R8 (PPOI5PE01WPPO 5) determined using SANS, SLS, DLS and rheometry (Morlensen 1997 Mortensen el al. 1994). Phases 1 and V are disordered micellar networks, V with excess water. Phases II and III are cubic micellar phases. Phase IV is a coexistence regime of micelles and crystalline layered PEO. (b) Schematic of the micellar network. 

Li and Caldwell used S-FFF to determine the mass and surface concentration of absorbed PEO-PPO-PEO triblock copolymers (Pluronics) onto PS latex standards [185]. Fl-FFF was found to work equally well for this problem. As experimental absorption problems are widespread and extremely relevant, it is expected that FFF will play an important future role in such studies, as long as the mass of the absorbed layer is sufficiently high. 

Non-Ionics of the C E -type have a very typical solubility behaviour, which is related to the EO-water interaction, hydration for short. First, poly(ethylene oxide), (PEO)jj is fairly soluble in water at room temperature, but polylpropylene oxide) (PPO) is not (as expected), and neither is poly(methylene oxide) (PMO), (unexpected). This irregular trend reminds us that solubility is not only determined by hydration in solution, but also by the Gibbs energy in the crystalline phase, which will be related to the molecular packing therein. Based on this difference in solubility, and hence in adsorbability, surface active polymers of the PEO-PPO type have been synthesized [Pluronics]-, they have a wide scope of application. 

Figure 4 Efficacy of Pluronic block copolymer compositions displayed in inhibiting drug efflux function in BBMEC monolayers. (A) Rhodamine 123 (R123) enhancement factors are defined here as the ratios of rhodamine 123 accumulation in the cells in the presence of the block copolymer to rhodamine 123 accumulation in the assay buffer. (B) A grid of Pluronic indicating four groups determined based on the activity of these copolymers displayed in BBMEC monolayers as shown in A. (From Ref. 95.)...

Peacock GF, Sauvageot J. Evaluation of the stability of acetaminophen in pluronic lecithin organogel and the determination of an appropriate beyond-use date. Int J Pharm Compd. 16(5) (2012) 428-430. 

The partial molar quantities of mixing were determined for normal and branched alkanes (O5 — Cio), cyclohexane, benzene and tetrachloromethane in polyisobutylene [57]. Partial molar enthalpies of mixing were measured for normal alkenes in low and high density polyethylene, polypropylene, polybutene-1, polystyrene, poly(methyl acrylate), poly(vinyl chloride), polyCN-isopropyl-acrylamide), ethylene-vinyl acetate copolymer, ethylene-carbon oxide copolymer [88] normal, branched and cyclic alkanes, benzene, n-butylbenzene, ois- and ra s-decalin, tetraline and naphthalene in polystyrene at 183, 193 and 203°C [60] these solutes in poly (methyl acrylate) [57] n-nonane, n-dodecane and benzene in polystyrene in the range 104.8 — 165.1 C [71] O7—C, C12 normal alkanes and aromatic hydrocarbons in polystyrene at an average temperature of 204.9°C [72], C7—Cg normal alkanes in poly(ethylene oxide) at an average temperature of 66.5 "C [72] normal alkanes in ethylene oxide—propylene oxide block copolymers (Pluronics L 72, L 64 and F 68) at the same average temperature [72]. 

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