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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this study was to develop and characterize hydrophilic gels containing chlorophyllin(CHL)-loaded liposomes as well as to evaluate their stability. Two different CHL-loaded liposome dispersions using non-hydrogenated and hydrogenated soybean lecithin were prepared, characterized for their particle size, polydispersity index and trapping efficiency and incorporated in Carbopol 940 NF hydrogel. The gels obtained were analyzed for flow properties, pH values and CHL content. The control liposome-free gel was obtained by incorporating the CHL solution in the hydrogel. The stability of the gels was evaluated in terms of rheological properties, pH values and CHL content during 6 months' storage at 20 +/- 2 degrees C. Suitable gel formulations for topical use were obtained revealing shear-thinning plastic flow behaviour without significant thixotropy during the whole period of examination. High yield values of the samples during the whole period indicated a long-term stability of the gel formulations. The gel formulations expressed a mild acid value acceptable for topical preparations. After 6 months' storage the CHL content was highest in the gel containing non-hydrogenated lecithin liposomes, followed by the gel containing hydrogenated lecithin liposomes and liposome-free gel, indicating that the encapsulation of CHL in liposomes led to a greater stability of CHL.
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PMID:Hydrophilic gels containing chlorophyllin-loaded liposomes: development and stability evaluation. 1612 1

The objective of this work was to develop and characterize semisolid topical formulations containing nimesulide-loaded nanospheres, nanocapsules or nanoemulsion. The nanoprecipitation and spontaneous emulsification methods were used to prepare the colloidal suspensions and the nanoemulsion. The hydrodynamic diameters were 282 nm for the nanoemulsion, 293 nm for the nanocapsules and 191 nm for the nanospheres containing nimesulide. The encapsulation efficiencies were close to 99% in all cases and pH values ranged between 5.1 and 5.3. Each drug-loaded nanocarrier formulation was incorporated in Carbopol 940 gels. The semisolid dosage forms showed yellowish, glossy and homogeneous aspect after the incorporation of the colloidal suspensions and nanoemulsion. The recovery of nimesulide and the pH values for the gels containing nanoemulsion, nanospheres or nanocapsules remained constant during storage (120 days). For all formulations, the rheograms exhibited a non-Newtonian behavior presenting pseudoplastic characteristics and shear thinning. The rheograms were adjusted to Ostwald's model showing regression coefficients higher than 0.9900. None thixotropic phenomenon was experimentally detected under the test conditions for all formulations.
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PMID:Semisolid topical formulations containing nimesulide-loaded nanocapsules, nanospheres or nanoemulsion: development and rheological characterization. 1639 65

Fluid dynamics of mucus plug rupture is important to understand mucus clearance in lung airways and potential effects of mucus plug rupture on epithelial cells at lung airway walls. We established a microfluidic model to study mucus plug rupture in a collapsed airway of the 12th generation. Mucus plugs were simulated using Carbopol 940 (C940) gels at concentrations of 0.15%, 0.2%, 0.25%, and 0.3%, which have non-Newtonian properties close to healthy and diseased lung mucus. The airway was modeled with a polydimethylsiloxane microfluidic channel. Plug motion was driven by pressurized air. Global strain rates and shear stress were defined to quantitatively describe plug deformation and rupture. Results show that a plug needs to overcome yield stress before deformation and rupture. The plug takes relatively long time to yield at the high Bingham number. Plug length shortening is the more significant deformation than shearing at gel concentration higher than 0.15%. Although strain rates increase dramatically at rupture, the transient shear stress drops due to the shear-thinning effect of the C940 gels. Dimensionless time-averaged shear stress, T xy , linearly increases from 3.7 to 5.6 times the Bingham number as the Bingham number varies from 0.018 to 0.1. The dimensionless time-averaged shear rate simply equals to T xy /2. In dimension, shear stress magnitude is about one order lower than the pressure drop, and one order higher than yield stress. Mucus with high yield stress leads to high shear stress, and therefore would be more likely to cause epithelial cell damage. Crackling sounds produced with plug rupture might be more detectable for gels with higher concentration.
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PMID:A microfluidic model to study fluid dynamics of mucus plug rupture in small lung airways. 2639 27