Comparison of Varve and 14C Chronologies from Steel Lake, Minnesota, USA (open access)

Comparison of Varve and 14C Chronologies from Steel Lake, Minnesota, USA

Annually laminated sediments (varves) offer an effective means of acquiring high-quality paleoenvironmental records. However, the strength of a varve chronology can be compromised by a number of factors, such as missing varves, ambiguous laminations, and human counting error. We assess the quality of a varve chronology for the last three millennia from Steel Lake, Minnesota, through comparisons with nine AMS {sup 14}C dates on terrestrial plant macrofossils from the same core. These comparisons revealed an overall 8.4% discrepancy, primarily because of missing/uncountable varves within two stratigraphic intervals characterized by low carbonate concentrations and obscure laminations. Application of appropriate correction factors to these two intervals results in excellent agreement between the varve and {sup 14}C chronologies. These results, together with other varve studies, demonstrate that an independent age-determination method, such as {sup 14}C dating, is usually necessary to verify, and potentially correct, varve chronologies.
Date: December 29, 2004
Creator: Tian, J; Brown, T A & Hu, F S
Object Type: Article
System: The UNT Digital Library
Development of Novel Water-Gas Shift Membrane Reactor (open access)

Development of Novel Water-Gas Shift Membrane Reactor

This report summarizes the objectives, technical barrier, approach, and accomplishments for the development of a novel water-gas-shift (WGS) membrane reactor for hydrogen enhancement and CO reduction. We have synthesized novel CO{sub 2}-selective membranes with high CO{sub 2} permeabilities and high CO{sub 2}/H{sub 2} and CO{sub 2}/CO selectivities by incorporating amino groups in polymer networks. We have also developed a one-dimensional non-isothermal model for the countercurrent WGS membrane reactor. The modeling results have shown that H{sub 2} enhancement (>99.6% H{sub 2} for the steam reforming of methane and >54% H{sub 2} for the autothermal reforming of gasoline with air on a dry basis) via CO{sub 2} removal and CO reduction to 10 ppm or lower are achievable for synthesis gases. With this model, we have elucidated the effects of system parameters, including CO{sub 2}/H{sub 2} selectivity, CO{sub 2} permeability, sweep/feed flow rate ratio, feed temperature, sweep temperature, feed pressure, catalyst activity, and feed CO concentration, on the membrane reactor performance. Based on the modeling study using the membrane data obtained, we showed the feasibility of achieving H{sub 2} enhancement via CO{sub 2} removal, CO reduction to {le} 10 ppm, and high H{sub 2} recovery. Using the membrane synthesized, we have obtained …
Date: December 29, 2004
Creator: Ho, W. S. Winston
Object Type: Report
System: The UNT Digital Library
Development of Novel Water-Gas Shift Membrane Reactor (open access)

Development of Novel Water-Gas Shift Membrane Reactor

None
Date: December 29, 2004
Creator: Ho, W. S. Winston
Object Type: Report
System: The UNT Digital Library
Final Report of the Grant: ''Vertical Transport and Mixing in Complex Terrain Airsheds'' (open access)

Final Report of the Grant: ''Vertical Transport and Mixing in Complex Terrain Airsheds''

Stable stratification associated with nocturnal thermal circulation in areas of complex terrain leads to interesting and important phenomena that govern local meteorology and contaminant dispersion. Given that most urban areas are in complex topography, understanding and prediction of such phenomena are of immediate practical importance. This project dealt with theoretical, laboratory, numerical and field experimental studies aimed at understanding stratified flow and turbulence phenomena in urban areas, with particular emphasis on flow, turbulence and contaminant transport and diffusion in such flows. A myriad of new results were obtained and some of these results were used to improve the predictive capabilities of the models.
Date: December 29, 2004
Creator: Fernando, Harindra Joseph; Anderson, James; Boyer, Don & Berman, Neil
Object Type: Report
System: The UNT Digital Library
An Internal LLNL Report: Spectroscopic Signature of Aging in (Delta)-Pu(Ga) (open access)

An Internal LLNL Report: Spectroscopic Signature of Aging in (Delta)-Pu(Ga)

Resonant Photoemission, a variant of Photoelectron Spectroscopy, has been demonstrated to have sensitivity to aging of Pu samples. The spectroscopic results are correlated with resistivity measurements and are shown to be the fingerprint of mesoscopic or nanoscale internal damage in the Pu physical structure. This means that a spectroscopic signature of internal damage due to aging in Pu has been established.
Date: December 29, 2004
Creator: Chung, B W; Fluss, M J; Haslam, J J; Schwartz, A J & Tobin, J G
Object Type: Article
System: The UNT Digital Library
Office Civilian Waste Management Transportation Institutional Program Update on Collaborative Efforts with Key Stakeholders (open access)

Office Civilian Waste Management Transportation Institutional Program Update on Collaborative Efforts with Key Stakeholders

The Department of Energy's (DOE) Office of Civilian Radioactive Waste Management (OCRWM) created the Office of National Transportation in 2003 recognizing the need to revitalize and accelerate development of the transportation system. The Department has made a commitment to work through a collaborative planning process before developing specific policies and procedures and making transportation decisions. OCRWM has begun to build the institutional framework to support development of this transportation system. Interactions with stakeholders have been initiated. The authors describe the key stakeholders, identified issues, regional and national planning activities, and mechanisms for interaction.
Date: December 29, 2004
Creator: Holm, Judith; Saris, Elizabeth; Austin, Paula & Offner, Julie J.
Object Type: Report
System: The UNT Digital Library