Photoinitiated electron transfer in multi-chromophoric species: Synthetic tetrads and pentads (open access)

Photoinitiated electron transfer in multi-chromophoric species: Synthetic tetrads and pentads

This research project involves the design, synthesis and study of the molecules which mimic many of the important aspects of photosynthetic electron and energy transfer. Specifically, the molecules are designed to mimic the following aspects of natural photosynthetic multistep electron transfer: electron donation from a tetrapyrrole excited singlet state, electron transfer between tetrapyrroles, electron transfer from tetrapyrroles to quinones, and electron transfer between quinones with different redox properties. In addition, they model carotenoid antenna function in photosynthesis (singlet-singlet energy transfer from carotenoid polyenes to chlorophyll) and carotenoid photoprotection from singlet oxygen damage (triplet-triplet energy transfer from chlorophyll to carotenoids).
Date: February 14, 1990
Creator: unknown
System: The UNT Digital Library
LLNL Waste Minimization Program Plan (open access)

LLNL Waste Minimization Program Plan

This document is the February 14, 1990 version of the LLNL Waste Minimization Program Plan (WMPP). The Waste Minimization Policy field has undergone continuous changes since its formal inception in the 1984 HSWA legislation. The first LLNL WMPP, Revision A, is dated March 1985. A series of informal revision were made on approximately a semi-annual basis. This Revision 2 is the third formal issuance of the WMPP document. EPA has issued a proposed new policy statement on source reduction and recycling. This policy reflects a preventative strategy to reduce or eliminate the generation of environmentally-harmful pollutants which may be released to the air, land surface, water, or ground water. In accordance with this new policy new guidance to hazardous waste generators on the elements of a Waste Minimization Program was issued. In response to these policies, DOE has revised and issued implementation guidance for DOE Order 5400.1, Waste Minimization Plan and Waste Reduction reporting of DOE Hazardous, Radioactive, and Radioactive Mixed Wastes, final draft January 1990. This WMPP is formatted to meet the current DOE guidance outlines. The current WMPP will be revised to reflect all of these proposed changes when guidelines are established. Updates, changes and revisions to the …
Date: February 14, 1990
Creator: unknown
System: The UNT Digital Library
Direct conversion of methane to C sub 2 's and liquid fuels (open access)

Direct conversion of methane to C sub 2 's and liquid fuels

Research on promoted metal oxide catalysts has continued with the study of alkaline earth/metal oxide halide catalysts. A barium bromide/alumina catalyst was comparable in methane conversion and selectivity to C{sub 2}'s to barium chloride/alumina catalysts. The effects of varying methane to oxygen feed ratios were explored for one of the best alkaline earth catalysts and one of the best literature catalysts (Li/MgO). A significant decrease in the selectivity to C{sub 2}'s is observed upon addition of ethane to the feed gas (feed gas methane/ethane ratio of 3). This observation demonstrates that a significant amount of ethane should not be recycled during methane oxidation over these types of catalysts under process conditions used. Methane oxidation over barium carbonate alone results in high enough selectivities and methane conversions to suggest an oxidized barium species may be responsible for methane oxidation on barium/metal oxide catalysts. Methane coupling studies have continued using layered perovskite catalysts in the cofeed mode and double perovskite catalysts in the sequential mode. Addition of sodium to the double perovskite LaCaMnCoO{sub 6} resulted in a catalyst with improved selectivity over the one without sodium. A reactor system containing two reactors in under construction. These reactors will be used to study …
Date: February 14, 1990
Creator: Warren, B. K.; Campbell, K. D. & Matherne, J. L.
System: The UNT Digital Library
Photoinitiated electron transfer in multi-chromophoric species: Synthetic tetrads and pentads. Technical progress report, 1987--1990 (open access)

Photoinitiated electron transfer in multi-chromophoric species: Synthetic tetrads and pentads. Technical progress report, 1987--1990

This research project involves the design, synthesis and study of the molecules which mimic many of the important aspects of photosynthetic electron and energy transfer. Specifically, the molecules are designed to mimic the following aspects of natural photosynthetic multistep electron transfer: electron donation from a tetrapyrrole excited singlet state, electron transfer between tetrapyrroles, electron transfer from tetrapyrroles to quinones, and electron transfer between quinones with different redox properties. In addition, they model carotenoid antenna function in photosynthesis (singlet-singlet energy transfer from carotenoid polyenes to chlorophyll) and carotenoid photoprotection from singlet oxygen damage (triplet-triplet energy transfer from chlorophyll to carotenoids).
Date: February 14, 1990
Creator: unknown
System: The UNT Digital Library
Synchrotron injectors based on high charge state ion sources (open access)

Synchrotron injectors based on high charge state ion sources

The performance of any injector contemplated to replace the electrostatic tandem accelerators some time in the future should evidently match or surpass the characteristics of the tandems. It is a fortunate coincidence that the performance of the BNL tandem satisfies in most respects the requirements of the proposed collider, although originally tandems were not built with this application in mind. Requests for heavy ion beams with parameters suitable for injection into the rings of a heavy ion collider have appeared rather recently, at a stage when the high charge state ion sources, which in principle are capable of producing many ion species, have not yet reached such a level of performance. Therefore, consideration of such sources as part of a future injector replacing the tandem accelerators will have to rely on the extrapolation of results from existing models, developed for a different purpose. At the same time, present and future collider requirements for heavy ion beams should serve as a stimulus for the development of sources producing ions with adequate charge states and intensities. Injectors based on such sources may present a better alternative than the tandem accelerators because a higher charge-to-mass ratio of ions from the source results in …
Date: February 14, 1990
Creator: Prelec, K.
System: The UNT Digital Library
D-Zero Signal Board Feed-Thru, Instrumentation and Hi-Voltage Boxes (open access)

D-Zero Signal Board Feed-Thru, Instrumentation and Hi-Voltage Boxes

The three boxes being reviewed all operate at a pressure of less than 15 psig. Since they are relieved at 13 psig, they fall outside the scopes of the ASME Pressure Vessel Code, Fermilab Engineering Standard SD-37B, and Chapter 5031 of the Fermilab Safety Manual, therefore a Pressure Vessel Engineering Note showing compliance with SD-37B is not required. In calculating the design stresses, only the largest of the three boxes, the signal board feed-thru box, was analyzed. This box had the largest spans and areas and would experience the largest pressure-related forces. The thinnest walls of each box were found to be in the top plates and they were also the side of the box which exposed the largest amount of area to internal pressure. The signal board feed-thru box top plate had at least twice the pressure area than either the instrumentation or hi-voltage boxes' top plates. This large disparity overshadows the slight difference in top plate thicknesses between the three boxes (0.56-inch vs. 0.25-inch and 0.3125-inch, respectively). Therefore, we felt the analysis of the larger signal board feedthru box would justify the design of the smaller instrumentation and hi-voltage boxes. Appended to the end of this engineering note …
Date: February 14, 1990
Creator: Luther, R.
System: The UNT Digital Library
Equipment upgrades for the Pu-238 program (open access)

Equipment upgrades for the Pu-238 program

Much of the equipment and instrumentation in the Pu-238 production facilities is more than 15 years old. Significant improvements have been made in the available instrumentation, in particular, due to the application of microprocessors and lasers. The Actinide Technology Section of SRL has selected and is in the process of evaluating several state-of-the-art instruments which have potential applications in the Pu-238 program. The ease of operation and the accuracy of the instruments have been improved and, in most cases, the cost of the instruments have decreased. 5 refs.
Date: February 14, 1990
Creator: Congdon, J. W.; Stephens, W. D.; Marra, J. E. & Nelson, G. H.
System: The UNT Digital Library