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Electron microscopy of biological macromolecules: Bridging the gapbetween what physics allows and what we currently can get (open access)

Electron microscopy of biological macromolecules: Bridging the gapbetween what physics allows and what we currently can get

The resolution achieved in low-dose electron microscopy of biological macromolecules is significantly worse than what can be obtained on the same microscopes with more robust specimens. When two-dimensional crystals are used, it is also apparent that the high-resolution image contrast is much less than what it could be if the images were perfect. Since specimen charging is one factor that might limit the contrast and resolution achieved with biological specimens, we have investigated the use of holey support films that have been coated with a metallic film before depositing specimens onto a thin carbon film that is suspended over the holes. Monolayer crystals of paraffin (C44H90) are used as a test specimen for this work because of the relative ease in imaging Bragg spacings at {approx}0.4 nm resolution, the relative ease of measuring the contrast in these images, and the similar degree of radiation sensitivity of these crystals when compared to biological macromolecules. A metallic coating on the surrounding support film does, indeed, produce a significant improvement in the high-resolution contrast for a small fraction of the images. The majority of images show little obvious improvement, however, and even the coated area of the support film continues to show a …
Date: April 30, 2003
Creator: Typke, Dieter; Downing, Kenneth H. & Glaeser, Robert M.
System: The UNT Digital Library
Assessing I-Grid(TM) web-based monitoring for power quality and reliability benchmarking (open access)

Assessing I-Grid(TM) web-based monitoring for power quality and reliability benchmarking

This paper presents preliminary findings from DOEs pilot program. The results show how a web-based monitoring system can form the basis for aggregation of data and correlation and benchmarking across broad geographical lines. A longer report describes additional findings from the pilot, including impacts of power quality and reliability on customers operations [Divan, Brumsickle, Eto 2003].
Date: April 30, 2003
Creator: Divan, Deepak; Brumsickle, William & Eto, Joseph
System: The UNT Digital Library
Analyzing occupancy profiles from a lighting controls field study (open access)

Analyzing occupancy profiles from a lighting controls field study

Despite a number of published studies on the effectiveness of lighting controls in buildings, only one US study examines the occupancy patterns of building occupants. Occupancy profiles allow one to determine, for example, the probability that an office is occupied for each hour of the workday. Occupancy profiles are useful for many purposes including: (1) predicting the effectiveness of occupancy sensors for reducing peak demand, (2) evaluating the impact of human activity on building lighting and other electric loads and (3) providing lighting equipment manufacturers with detailed lighting operation data to help evaluate the impact of advanced lighting controls on equipment life. In this paper, we examine the occupancy profiles for 35 single person offices at a large office building in San Francisco and analyze the data to obtain average occupancy as a function of time of day. In addition, we analyzed the data to identify how the use of occupancy sensors may affect switching cycles and lamp life.
Date: April 30, 2003
Creator: Rubinstein, Francis; Colak, Nesrin; Jennings, Judith & Neils, Danielle
System: The UNT Digital Library
Prospects for higgs search at D0 (open access)

Prospects for higgs search at D0

The D0 experiment is recording physics quality data. Both the detector and the accelerator performance are continually improving. We are studying issues such as the b{bar b} mass resolution, b-jet tagging efficiency, missing E{sub T} resolution, and backgrounds to Higgs processes. We look forward to seeing exciting results. The status of the Higgs search at the upgraded D0 detector is discussed.
Date: April 30, 2003
Creator: Snyder, Scott S.
System: The UNT Digital Library
Mullite/Mo interfaces formed by Intrusion bonding (open access)

Mullite/Mo interfaces formed by Intrusion bonding

The microstructure and strength of Mo/mullite interfaces formed by diffusion bonding at 1650 C has been analyzed. Interfacial metal-ceramic interlocking contributes to flexural strength of approx. 140 MPa as measured by 3 point bending. Saturation of mullite with MoO2 does not affect the interfacial strength.
Date: April 30, 2003
Creator: Bartolome, Jose F.; Diaz, Marcos; Moya, Jose S.; Saiz, Eduardo & Tomsia, Antoni P.
System: The UNT Digital Library
Transport in a Microfluidic Catalytic Reactor (open access)

Transport in a Microfluidic Catalytic Reactor

A study of the heat and mass transfer, flow, and thermodynamics of the reacting flow in a catalytic microreactor is presented. Methanol reforming is utilized in the fuel processing system driving a micro-scale proton exchange membrane fuel cell. Understanding the flow and thermal transport phenomena as well as the reaction mechanisms is essential for improving the efficiency of the reforming process as well as the quality of the processed fuel. Numerical studies have been carried out to characterize the transport in a silicon microfabricated reactor system. On the basis of these results, optimized conditions for fuel processing are determined.
Date: April 30, 2003
Creator: Park, Hyun Gyu; Chung, Jaewon; Grigoropoulos, Costas P.; Greif, Ralph; Havstad, Mark & Morse, Jeffrey D.
System: The UNT Digital Library