Biomedical subjects

Sarah E Morgan

Publications and source records attributed to Sarah E Morgan.

3 recordsLinked to original sources

PubMed2007

Layer-by-layer assembly of pH-responsive, compositionally controlled (co)polyelectrolytes synthesized via RAFT.

Homo- and block copolyelectrolytes that have well-defined structures and are responsive to pH were synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization and employed to produce layer-by-layer (LBL) films. Acrylamido monomers with carboxylate, sulfonate, and amine functionality were utilized to provide both strong and weak homopolyelectrolytes and mixed strong/weak copolyelectrolyte systems. Multilayer films were prepared under specified conditions of pH and ionic strength and analyzed via atomic force microscopy and ellipsometry to study the effects of changes in the local molecular environment on film morphologies. The pH responsiveness and integrity of the multilayer assemblies were investigated by exposing films to solutions of varying pH in a fluid cell and performing in situ AFM analysis. The multilayer dimensions, morphology, and integrity were found to depend on the molecular architecture of the polyelectrolytes, with changes in segmental type and repeating unit distribution producing dramatic differences in film characteristics. These results suggest the possibility of producing LBL assemblies of precisely controlled dimensions and properties by specifically tailoring copolymer structure. To our knowledge, this is the first report of LBL assembly of RAFT-synthesized homo- and copolyelectrolyte multilayer complexes.

Journal Article↗

PubMed2006

Nanoscale reduction in surface friction of polymer surfaces modified with Sc3 hydrophobin from Schizophyllum commune.

Hydrophobins are amphipathic self-assembling proteins secreted by filamentous fungi that exhibit remarkable ability to modify synthetic surfaces. Thin coatings of Sc3 hydrophobin isolated from the wood-rotting fungus Schizophyllum commune were prepared via spin coating and adsorption techniques onto polymeric surfaces. Surface morphology and nanotribological characteristics of the films were evaluated using lateral force microscopy (LFM) and nanoindentation techniques. This paper reports the first observation of reduction in nanoscale relative surface friction of Sc3 hydrophobin protein modified polymeric surfaces. Relative friction coefficients were dramatically reduced and hydrophilicity increased for polymer surfaces modified with Sc3 hydrophobin thin films. Morphology of the protein films as well as degree of surface modification was observed to be a function of film formation technique and composition of the substrate.

Adsorption↗

PubMedDate not supplied

The Balanced Budget Act of 1997 and the financial health of teaching hospitals.

BACKGROUND: We wanted to evaluate the most recent, complete data related to the specific effects of the Balanced Budget Act of 1997 relative to the overall financial health of teaching hospitals. We also define cost report variables and calculations necessary for continued impact monitoring. METHODS: We undertook a descriptive analysis of hospital cost report variables for 1996, 1998, and 1999, using simple calculations of total, Medicare, prospective payment system, graduate medical education (GME), and bad debt margins, as well as the proportion with negative total operating margins. RESULTS: Nearly 35% of teaching hospitals had negative operating margins in 1999. Teaching hospital total margins fell by nearly 50% between 1996 and 1999, while Medicare margins remained relatively stable. GME margins have fallen by nearly 24%, however, even as reported education costs have risen by nearly 12%. Medicare + Choice GME payments were less than 10% of those projected. CONCLUSIONS: Teaching hospitals realized deep cuts in profitability between 1996 and 1999; however, these cuts were not entirely attributable to the Balanced Budget Act of 1997. Medicare payments remain an important financial cushion for teaching hospitals, more than one third of which operated in the red. The role of Medicare in supporting GME has been substantially reduced and needs special attention in the overall debate. Medicare + Choice support of the medical education enterprise is 90% less than baseline projections and should be thoroughly investigated. The Medicare Payment Advisory Commission, which has a critical role in evaluating the effects of Medicare policy changes, should be more transparent in its methods.

Budgets↗