Biomedical subjects

A Aserin

Publications and source records attributed to A Aserin.

2 recordsLinked to original sources

PubMed1997

Structural Polymorphism in a Four-Component Nonionic Microemulsion

The Winsor IV microemulsion system composed of octaethylene glycol mono n-dodecylether [C12(EO)8]/1-dodecane + n-pentanol (1:1 by weight)/water has been investigated at constant temperature using small angle X-ray scattering and electrical conductivity measurements. The results obtained are interpreted in terms of structural evolution of the molecular aggregates as a function of the stepwise addition of water or (oil + alcohol). The size and shape of a variety of microstructures are described: small, spherical micelles near the water corner and hexagonal and lamellar mesophases, which are oil- and alcohol-poor. Simple multishell models of these provide some insight into how dilution with water or swelling with (oil + alcohol) influences the overall symmetry of the aggregates, pentanol and dodecane partitioning, surfactant headgroup conformation, and the contribution of pentanol to oil solubilization. The previously identified "local" lamellar structure [O. Regev et al., Langmuir 12, 668 (1996)], which is a surfactant-rich and (oil + alcohol)-rich intermediate state between the W/O and O/W regions, is characterized here as a type of ordered, but highly obstructed, bicontinuous microemulsion.

Journal Article↗

PubMedDate not supplied

Catheter obstruction: analysis of filter content of total nutrient admixture.

Catheter blockage in patients receiving long-term parenteral nutrition with fat-containing total nutrient admixture (TNA) is a relatively common complication. A study was carried out to characterize the material which is filtered out of the TNA and is a potential cause of catheter blockage. A total of 45 bags containing the same TNA solution were stored for 7 days at 4 degrees C. The stability of the solution in all the bags was then confirmed by light microscope and Coulter Counter, to determine the particle-size distribution, following which the solution was filtered through a 5-microns filter. Chemical analysis was then made to determine the amount of solid particles, fat and precipitates of Mg, Zn, Ca, Na, and K in the filter contents. Each bag was found to contain 7326 +/- 2681 solid particles as plasticizers and the main component of the filter contents was fat (99.4%) whereas electrolytes as precipitates constituted less than 0.5%. The amount of fat and electrolytes lost on the filter from the solution was negligible. Our analysis of the material trapped on the filter, which may block the catheter during long-term therapy, suggests the importance of filtration and of finding a means for dissolving the fat, the main component of the filter material.

Catheterization, Peripheral↗