Use of cyclodextrins for manipulating cellular cholesterol content

Previous studies from this laboratory have demonstrated that exposure of tissue culture cells to cyclodextrins results in rapid cholesterol depletion. In the present study, we have developed experimental systems for using solutions of cyclodextrins, either 2-hydroxypropyl beta-cyclodextrin or methylated beta-cyclodextrin, complexed with varying amounts of free cholesterol to manipulate cell cholesterol content. Cholesterol delivered via the cyclodextrin has been found to be metabolically active, as measured by the acyl-coenzyme A:cholesterol acyltransferase (ACAT)-mediated esterification of [3H]cholesterol in Fu5AH rat hepatoma cells and Chinese hamster ovary cells. The methylated beta-cyclodextrin was found to be a more efficient donor in all cell types studied, with an average cholesterol uptake of at least 100 microg cholesterol/mg protein within 6 h. By modifying the cyclodextrin:cholesterol molar ratio, it is possible to manipulate the cellular cholesterol content of cells, producing conditions ranging from net cholesterol enrichment to depletion. The use of cyclodextrins provides a convenient, precise and reproducible method for modulating the cholesterol content of tissue culture cells.     

The reactions of nitromethane in the gas phase and on a Co-ZSM5 catalyst under the conditions of the methane/NOx SCR reaction

The rate of reaction of nitromethane in the gas phase is little changed by the presence of O₂ or NO. The major products are CO, NO and H₂O, plus NO₂ if O₂ is included. The corresponding catalytic reaction over fresh Co-ZSM5 commences at a much lower temperature and gives primarily CO₂ and NH₃, the latter being oxidised to N₂ above 340°C. As the catalyst ages below 320°C HNCO eventually becomes the major nitrogen-containing product although it can be hydrolysed by added water. The results demonstrate one possible route for the methane-SCR reaction. This revised version was published online in July 2006 with corrections to the Cover Date.     

A sensitivity assessment of uncertainty in infrastructure expansion

Under and overdesign is a major consideration in public infrastructure expansion. Traditional engineering economies of scale leading to overdesign errors must be counterbalanced by greater attention to high cost financing. Uncertainty in demand forecasting and in financial markets make decision tools which incorporate measures of information imperfection increasingly important. Further issues of overall social welfare make the question of short term and intergenerational equity major concerns. A rational expectations stochastic-analog of the conventional, present value, infrastructure expansion model has optimal overdesign properties. The problem is restated as a two-person, planner vs. future, social welfare game in a simple capital loss model. Sensitivity analysis shows the game-theoretic model which favors expansion underdesign is relatively less sensitive to greater demand forecast uncertainty than the rational expectations model.     

Microstructural Analysis and Transport Properties of Thermally Sprayed Multiple-Layer Ceramic Coatings

Multilayer, graded ceramic/metal coatings were prepared by an air plasma spray method on Ti-6Al-4V, 4140 steel and graphite substrates. The coatings were designed to provide thermal barriers for diesel engine pistons to operate at higher temperatures with improved thermal efficiency and cleaner emissions. A systematic, progressive variation in the mixture of yttria-stabilized zirconia and bondcoat alloys (NiCoCrAlYHfSi) was designed to provide better thermal expansion match with the substrate and to improve thermal shock resistance and cycle life. Heat transfer through the layers was evaluated by a flash diffusivity technique based on a model of one-dimensional heat flow. The aging effect of the as-sprayed coatings was captured during diffusivity measurements, which included one heating and cooling cycle. The hysteresis of thermal diffusivity due to aging was not observed after 100-h annealing at 800 °C. The measurements of coatings on substrate and freestanding coatings allowed the influence of interface resistance to be evaluated. The microstructure of the multilayer coating was examined using scanning electron microscope and electron probe microanalysis.     

Technologies and the development of the Automated Metadata Indexing and Analysis (AMIA) system

The Automated Metadata Indexing and Analysis (AMIA) project aims to provide an effective digital asset management (DAM) tool for large digital asset databases. We began with text-based indexing since it is still the most reliable approach as compared with other content-based media features. AMIA not only searches for the text of the file name, but also utilizes embedded information such as the metadata in Maya files. The AMIA system builds a linked map between all dependency files. We present an approach of preserving previously established metadata created by the old DAM tools, such as AlienBrain, and integrating them into the new system. Findings indicate that AMIA has significantly improved search performance comparing to previous DAM tools. Finally, the ongoing and future work in the AMIA project is described.     

Investigation of a Dipole Model for Transient Analysis of Electromagnetic Field Coupling into Long Cables

The authors describe a mathematical model for a long conductor exposed to a high-intensity transient electric field to aid in determining interface requirements at connected equipment. Dipole characteristics of the conductors are used to simulate the impedance and in turn to calculate the induced currents. Example calculations for four models, two conductor lengths, and two conductor sizes, are presented and compared.     

Nuclear magnetic resonance analysis of solution conformations in C4-V3 hybrid peptides derived from human immunodeficiency virus (HIV) type 1 gp120: relation to specificity of peptide-induced anti-HIV neutralizing antibodies

Immunogenic peptides containing epitopes of the gp120 C4 and V3 regions from human immunodeficiency virus strains MN and EV91 have been studied by nuclear magnetic resonance and molecular modeling and used as immunogens in rhesus monkeys. The results, combined with those for other peptides, suggest a correlation between solution conformation and immunologic cross-reactivity.