Kim Kim

Adding small fractions of cholesterol decreases the interfacial viscosity of dipalmitoylphosphatidylcholine monolayers by an order of magnitude per wt %. Grazing incidence X-ray diffraction shows that cholesterol at these small fractions does not mix ideally with DPPC but rather induces nanophase separated structures of an ordered, primarily DPPC phase bordered by a line-active, disordered, mixed DPPC-cholesterol phase. We propose that the free area in the classic Cohen and Turnbull model of viscosity is inversely proportional to the number of molecules in the coherence area, or product of the two coherence lengths. Cholesterol significantly reduces the coherence area of the crystals as well as the interfacial viscosity. Using this free area collapses the surface viscosity data for all surface pressures and cholesterol fractions to a universal logarithmic relation. The extent of molecular coherence appears to be a fundamental factor in determining surface viscosity in ordered monolayers. © 2014 American Chemical Society.

This study investigated the perceptions and attitudes of ICU nurses towards the ‘do not resuscitate’ (DNR) decision and changes in their nursing activities after implementation of the DNR decision in South Korea. A data survey was conducted in South Korea between August and October 2008, with a convenience sample of 252 ICU nurses who had more than one year of clinical experience. The data were collected via a self-administered questionnaire. Most of the nurses perceived the necessity of the DNR decision in cases where there would be no chance of patient recovery despite massive efforts. Very few of the nurses' activities changed, either passively or actively, after implementation of the DNR decision. Moreover, the findings of this research provide suggestions for the future direction of the DNR decision and ethical nursing guidelines in South Korea. Further investigations are needed for the development of decision-making skills and intervention guidelines for end-of-life nursing.