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Structural oxidation state studies of the manganese cluster in the oxygen evolving complex of photosystem II

Description: X-ray absorption spectroscopy (XAS) was performed on Photosystem II (PSII)-enriched membranes prepared from spinach to explore: (1) the correlation between structure and magnetic spin state of the Mn cluster in the oxygen evolving complex (OEC) in the S{sub 2} state; and (2) the oxidation state changes of the Mn cluster in the flash-induced S-states. The structure of the Mn cluster in the S{sub 2} state with the g{approx}4 electron paramagnetic resonance (EPR) signal (S{sub 2}-g4 state) was compared with that in the S{sub 2} state with multiline signal (S{sub 2}-MLS state) and the S{sub 1} state. The S{sub 2}-g4 state has a higher XAS inflection point energy than that of the S{sub 1} state, indicating the oxidation of Mn in the advance from the S{sub 1} to the S{sub 2}-g4 state. Differences in the edge shape and in the extended X-ray absorption fine structure (EXAFS) show that the structure of the Mn cluster in the S{sub 2}-g4 state is different from that in the S{sub 2}-MLS or the S{sub 1} state. In the S{sub 2}-g4 state, the second shell of backscatterers from the Mn absorber contains two Mn-Mn distances of 2.73 {angstrom} and 2.85 {angstrom}. Very little distance disorder exists in the second shell of the S{sub 1} or S{sub 2}-MLS states. The third shell of the S{sub 2}-g4 state at about 3.3 {angstrom} also contains increased heterogeneity relative to that of the S{sub 2}-MLS or the S{sub 1} state. Various S-states were prepared at room-temperature by saturating, single-turnover flashes. The flash-dependent oscillation in the amplitude of the MLS was used to characterize the S-state composition and to construct {open_quotes}pure{close_quotes} S-state Mn K-edge spectra. The edge position shifts to higher energy by 1.8 eV upon the S{sub 1} {yields} S{sub 2} transition.
Date: November 1, 1994
Creator: Liang, W.
Partner: UNT Libraries Government Documents Department

Investigation of oil recovery improvement by coupling an interfacial tension agent and a mobility control agent in light oil reservoirs. Technical progress report, January--March 1994

Description: The study will investigate two major areas concerning co-injecting an interfacial tension reduction agent(s) and a mobility control agent into petroleum reservoirs. The first will consist of defining the mechanisms of interaction of an alkaline agent, a surfactant, and a polymer on a fluid-fluid and a fluid-rock basis. The second is the improvement of the economics of the combined technology. This report examines the adsorption of alkali, surfactant, and polymer onto crushed Berea sandstone.
Date: December 31, 1994
Creator: Pitts, M.J.
Partner: UNT Libraries Government Documents Department

Small angle neutron scattering study of the micelle structure of amphiphilic block copolymers

Description: The amphiphilic block copolymers of vinyl ether were prepared by living cationic polymerization. The partially deuterated copolymers for SANS experiments were especially synthesized by introducing deuterated phenyl units in the hydrophobic chain. SANS measurements were performed for aqueous solutions of these copolymers by changing H{sub 2}O/D{sub 2}O ratios. The SANS profiles indicate that the micelles in the present system exhibit a core-shell structure and that the size and shape of micelles are largely dependent on the length of hydrophobic chain. The micelle of shorter hydrophobic chain was found to be nearly spherical, whereas the micelle of longer hydrophobic chain was confirmed to have an ellipsoidal shape.
Date: July 31, 1994
Creator: Yamaoka, H.; Matsuoka, H.; Sumaru, K.; Hanada, S.; Imai, M. & Wignall, G. D.
Partner: UNT Libraries Government Documents Department

The effect of iodide and pH on the adsorption of mercury(II) to illite

Description: Effect of I{sup -} concentration on mobility of Hg(II) in clay suspensions was studied over an environmentally significant pH range. The addition of I{sup -} decreased the adsorption of Hg(II), except at very low (50 {mu}g/L) I{sup -} concentrations. In suspensions of greater I{sup -} concentration (1.5 and 50 mg/L). Hg(II) adsorption increased with pH, presumably due to formation of Hg-OH complexes; at low concentrations, Hg(II) adsorption decreased with pH, presumably due to competition from hydrocomplexes for surface adsorption sites. I{sup -} was an effective extractant for Hg(II), outperforming all other halides in extraction efficiency.
Date: December 31, 1994
Creator: Hamilton, W.P.; Ghosh, M.M. & Turner, R.R.
Partner: UNT Libraries Government Documents Department

Chemical and electrical properties of cavities in silicon and germanium

Description: Cavities were formed in Si and Ge by He ion implantation and annealing, and resultant chemical and electrical properties were investigated. The dissociation energies for Si-H and Ge-H surface monohydride bonds were determined, showing that H chemisorption on Si is energetically stable with respect H{sub 2} gas whereas H chemisorption on Ge is not. Cavity walls in Si were found to trap transition metals strongly, suggesting application to impurity gettering in devices. Measurement and modeling of cavity electrical properties elucidated surface electronic states and indicated a potential for controlled electrical isolation in devices. 35 refs.
Date: December 31, 1994
Creator: Myers, S.M.; Follstaedt, D.M.; Petersen, G.A.; Seager, C.H.; Stein, H.J. & Wampler, W.R.
Partner: UNT Libraries Government Documents Department

Metal ion complexation by ionizable crown ethers. Final report, January 1, 1988--June 30, 1994

Description: During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. The ligands possess one or more ionizable group (carboxylic acid, phosphonic acid monoethyl ester, para-nitrophenol, phosphonic acid) attached to crown ether, monoazacrown ether or diazacrown ether frameworks. These novel chelating agents have either pendent or inward-facing proton-ionizable groups. Such lipophilic proton-ionizable crown ethers are designed for use in multiphase metal ion separations (solvent extraction, liquid membrane transport). In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent and variation of the stripping conditions have been assessed. The influence of structural variations within lipophilic acyclic polyether dicarboxylic acids upon competitive solvent extraction of alkaline earth cations has been probed. Also a new chromogenic, di-ionizable crown ether with extremely high selectivity for Hg{sup 2+} has been discovered.
Date: December 31, 1994
Creator: Bartsch, R. A.
Partner: UNT Libraries Government Documents Department

{sup 222}Rn in water: A comparison of two sample collection methods and two sample transport methods, and the determination of temporal variation in North Carolina ground water

Description: Objectives of this field experiment were: (1) determine whether there was a statistically significant difference between the radon concentrations of samples collected by EPA`s standard method, using a syringe, and an alternative, slow-flow method; (2) determine whether there was a statistically significant difference between the measured radon concentrations of samples mailed vs samples not mailed; and (3) determine whether there was a temporal variation of water radon concentration over a 7-month period. The field experiment was conducted at 9 sites, 5 private wells, and 4 public wells, at various locations in North Carolina. Results showed that a syringe is not necessary for sample collection, there was generally no significant radon loss due to mailing samples, and there was statistically significant evidence of temporal variations in water radon concentrations.
Date: December 31, 1994
Creator: Hightower, J. H., III
Partner: UNT Libraries Government Documents Department

Base hydrolysis and hydrothermal processing of PBX-9404 explosive

Description: Base hydrolysis in combination with hydrothermal processing has been proposed as an environmentally acceptable alternative to open burning/open detonation for degradation and destruction of high explosives. In this report, we examine gaseous and aqueous products of base hydrolysis of the HMX-based plastic bonded explosive, PBX-9404. We also examine products from the subsequent hydrothermal treatment of the base hydrolysate. The gases produced from hydrolysis of PBX-9404 are ammonia, nitrous oxide, and nitrogen. Major aqueous products are sodium formate, acetate, nitrate, and nitrite, but not all carbon products have been identified. Hydrothermal processing of base hydrolysate destroyed up to 98% of the organic carbon in solution, and higher destruction efficiencies are possible. Major gas products detected from hydrothermal processing were nitrogen and nitrous oxide.
Date: December 31, 1994
Creator: Sanchez, J.A.; Flesner, R.L.; Spontarelli, T.; Dell`Orco, P.C. & Kramer, J.F.
Partner: UNT Libraries Government Documents Department

Vaporization of actinide oxides in thermal treatment processes for mixed waste

Description: The purpose of this study is to evaluate the volatilities of U, Pu, and Am in thermal treatment processes for mixed wastes. The thermodynamics of vaporization U and Pu oxides in the presence of oxygen and water vapor and of U oxide in the presence of oxygen and chlorine were studied. Experimental studies of U oxide volatilities by previous authors have also been reviewed. For species where data are unavailable estimation methods were used to obtain free energies of formation of the gaseous species, The data are applied to thermal treatment processes in general and then more specifically to conditions representative of the Rocky Flats Plant Fluidized Bed Unit. (RFP FBU), molten salt oxidizer, and an incinerator. U volatilities are greatest ranging from 2.67 x 10{sup -7} gU/h in the RFP FBU to 4. 00 gU/h for typical incinerator conditions. Pu volatilities are almost 5 orders of magnitude less than U and Am volatilities are about 3 orders of magnitude less than Pu.
Date: October 4, 1994
Creator: Ebbinghaus, B. B.; Krikorian, O. H. & Adamson, M. G.
Partner: UNT Libraries Government Documents Department

Calorimetry exchange program. Annual data report, Calendar Year 1993

Description: A sample of PuO{sub 2} powder is available at each participating site for NDA measurement, including either or both calorimetry and high-resolution gamma-ray spectroscopy, the elements which are typically combined to provide a calorimetric assay of plutonium. The facilities measure the sample as frequently and to the level of precision which they desire, and then submit the data to the Exchange for analysis. The data report includes summary tables for each measurement and charts showing the performance of each laboratory. Comparisons are made to the accepted values for the exchange sample and to data previously reported by that laboratory. This information is presented, in the form of quarterly and annual reports, intended for use by Exchange participants in measurement control programs, or to indicate when bias corrections may be appropriate. No attempt, however, has been made to standardize methods or frequency of data collection, calibration, or operating procedures. Direct comparisons between laboratories may, therefore, be misleading since data have not been collected to the same precision or for the same time periods. A meeting of the participants of the Calorimetry Exchange is held annually at EG&G Mound Applied Technologies. The purposes of this meeting are to discuss measurement differences, problems, and new measurement capabilities, and to determine the additional activities needed to fulfill the goals of the Exchange.
Date: 1994
Creator: Barnett, T. M.
Partner: UNT Libraries Government Documents Department

Chemical synthesis, characterization and separation studies of functionalized polymeric supports. Final report

Description: Polymer resins with immobilized phosphorus acid ligands have been used to remove metal ions from solutions over wide pH range. These resins offer selective removal of metal ions under acidic conditions through coordination with the phosphoryl oxygen. Use of poly(vinylbenzyl chloride) foams as supports for phosphorus-based ligands is examined in this report. Foams with large pore volumes as supports offer an advantage over gel and macroporous beads in that the increased porosity could lead to increased rates of metal ion complexation, and the larger pore size allows the use of more hydrophobic ligands such as phosphonate esters in metal ion complexations from aqueous solutions. Effects of crosslinking and sulfonation on metal ion complexation are also studied.
Date: October 27, 1994
Creator: Alexandratos, S.D. & Beauvais, R.
Partner: UNT Libraries Government Documents Department

Responsive copolymers for enhanced petroleum recovery. Quarterly technical progress report, September 11, 1994--December 22, 1994

Description: Advanced polymer systems that possess microstructural features that are responsive to temperature, electrolyte concentration, and shear conditions are being synthesized which will be superior to polymers presently used for mobility control in enhanced oil recovery. Improved polymer performance is accomplished by controlling hydrophobic or ampholytic interations between individual polymer chains in solution. The advanced polymers will circumbent major problems inherent in conventional EOR polymers in which molecular weight is usually compromised to allow sufficient solution viscosity and uniform reservoir permeation without plugging the porous media. Accomplishments are reported for the following tasks: quaternary ammonium cyclopolymer synthesis; characterization of molecular structure and solution behavior; {sup 23}Na NMR studies of non-binding to anionic polyelectrolytes and solution rheology.
Date: January 1, 1994
Creator: McCormick, C. & Hester, R.
Partner: UNT Libraries Government Documents Department

Synthesis and properties of lanthanide-exchanged Preyssler`s heteropolyanions

Description: Na{sup +} in the Preyssler heteropolytungstate anion [NaP{sub 5}W{sub 30}O{sub 110}]{sup 14{minus}} can be exchanged for a trivalent lanthanide ion. The potential significance of this new class of lanthanide heteropolyanions relates to their applications in catalysis science. This view follows from the fact that Keggin heteropolyanions and their free acids are used as heterogeneous solid catalysts and homogeneous solution catalysts. The authors describe synthetic conditions that lead to the incorporation of Ce{sup 3+} and Pr{sup 3+} within the Preyssler anion, and the coprecipitation of Ce{sup 3+} and the Preyssler anion. Initial studies indicate that the latter, coprecipitated, material deserves study for bifunctional catalytic activity.
Date: December 1994
Creator: Antonio, M. R.; Malinsky, J. & Soderholm, L.
Partner: UNT Libraries Government Documents Department

Field analysis of mercury in water, sediment and soil using static headspace analysis

Description: We developed a field screening method for rapid analysis of Hg in water, soil, and sediment, which can be applied cost-effectively at Hg-contaminated sites. Samples are chemically pretreated in ordinary containers, followed by analysis of the sample headspace Hg vapor using a portable commercial analyzer. Hg in water samples is reduced directly by the addition of stannous chloride, while solids are first digested with aqua regia or piranha solution to liberate the Hg from the solids. Aided by vigorous agitation after adding the reductant, the elemental Hg partitions between solution and headspace according to Henry`s Law. The method requires about 2 and 15 minutes to complete for water and solids, respectively. The method provides very useful detection limits for water (0.1 {mu}g/L) and solids (2-3{mu}g/g). Intercomparisons with laboratory-analyzed environmental samples show good agreement.
Date: December 31, 1994
Creator: Kriger, A.A. & Turner, R.R.
Partner: UNT Libraries Government Documents Department

Docmentation of newly developed methods to assess material compatibility in refrigeration and air-conditioning applications. Final report, 1 October 1993--31 August 1994

Description: This document summarizes the experimental methods used during the materials compatibility and lubricants research program (MCLR). The MCLR program was jointly sponsored by the U.S. Department of Energy and the air-conditioning and refrigeration industry. The individual projects were managed by the Air-Conditioning and Refrigeration Technology Institute. The projects presented in this report are: Chemical and Thermal Stability of Refrigerant/Lubricant Mixtures with Metals, Miscibility of Lubricants with Refrigerants, Compatibility of Refrigerants and Lubricants with Motor Materials, Compatibility of Refrigerants and Lubricants with Elastomers, Compatibility of Refrigerants and Lubricants with Engineering Plastics and Sealed Tube Comparisons of the Compatibility of Desiccants with Refrigerants and Lubricants.
Date: August 1, 1994
Creator: Hawley, M.
Partner: UNT Libraries Government Documents Department

Mathematical modeling of liquid/liquid hollow fiber membrane contactor accounting for interfacial transport phenomena: Extraction of lanthanides as a surrogate for actinides

Description: This report is divided into two parts. The second part is divided into the following sections: experimental protocol; modeling the hollow fiber extractor using film theory; Graetz model of the hollow fiber membrane process; fundamental diffusive-kinetic model; and diffusive liquid membrane device-a rigorous model. The first part is divided into: membrane and membrane process-a concept; metal extraction; kinetics of metal extraction; modeling the membrane contactor; and interfacial phenomenon-boundary conditions-applied to membrane transport.
Date: August 4, 1994
Creator: Rogers, J. D.
Partner: UNT Libraries Government Documents Department

Experimental and theoretical investigation of the product channels of the O + CH{sub 3} reaction

Description: The product channels of the O({sup 3}P)+CH{sub 3} reaction was investigated. In the experimental part, the branching fraction for formaldehyde production (O+CH{sub 3}{r_arrow}H{sub 2}CO+H) was measured at room temperature in a tubular flow reactor coupled to a photoionization mass spectrometer. The reactants (CH{sub 3} and O) were generated homogeneously in the reactor by simultaneous {ital in}{ital situ} 193-nm photolysis of acetone and SO{sub 2}. Formaldehyde yield relative to the methyl radicals consumed (branching fraction) was determined to be 1.0{+-}0.15. In the theoretical part, calculations of the energetics of possible decomposition pathways of the energy-rich methoxy radical initially formed in the O+CH{sub 3} reaction indicate that the dominant channel for decomposition is C-H bond cleavage leading to atomic hydrogen and formaldehyde. A possible, minor, secondary channel is hydrogen migration, followed by O-H bond cleavage, leading to the same final products. No energetically competitive pathways leading to H{sub 2}, HCO, HOC, or CO could be found.
Date: May 1, 1994
Creator: Slagle, I.R.; Kalinovski, I.J.; Gutman, D. & Harding, L.B.
Partner: UNT Libraries Government Documents Department

SIMS analysis: Development and evaluation 1994 summary report

Description: Secondary ion mass spectrometry (SIMS) was evaluated for applicability to the characterization of salt cake and environmental samples. Salt cake is representative of waste found in radioactive waste storage tanks located at Hanford and at other DOE sites; it consists of nitrate, nitrite, hydroxide, and ferrocyanide salts, and the samples form the tanks are extremely radioactive. SIMS is an attractive technology for characterizing these samples because it has the capability for producing speciation information with little or no sample preparation, and it generates no additional waste. Experiments demonstrated that substantial speciation information could be readily generated using SIMS: metal clusters which include nitrate, nitrite, hydroxide, carbonate, cyanide, ferrocyanide and ferricyanide were observed. In addition, the mechanism of SIMS desorption of tributyl phosphate (TBP) was clearly identified, and minimum detection limit studies involving TBP were performed. Procurements leading to the construction of an ion trap SIMS instrument were initiated. Technology transfer of SIMS components to three instrument vendors was initiated. For FY-95, the SIMS evaluation program has been redirected toward identification of metal species on environmental samples.
Date: December 1994
Creator: Groenewold, G. S.; Appelhans, A. D.; Ingram, J. C.; Delmore, J. E. & Dahl, D. A.
Partner: UNT Libraries Government Documents Department

Development of proposed free release criteria for Idaho National Engineering Laboratory lead

Description: The INEL Lead Management Project (LMP) performed an investigation of the origin of lead used as shielding at the INEL and developed radiological profile information that was then used to establish a baseline for the DOE ``no-rad-added`` standard. Primary findings of the investigation include the following: (a) Much of the lead at the INEL was obtained from a DOE lead bank; (b) Lead inventory at the DOE lead bank was derived primarily from recycled sources and was most likely in the form of pure lead; (c) Secondary lead (lead from recycled sources), available in today`s market, is expected to have radiological characteristics similar to those of the DOE lead bank; (d) Highly sensitive radiological testing of 20 samples of lead from secondary sources revealed the lead to be radiologically pristine. Beta-, gamma-, and alpha-emitting radionuclide concentrations were all found to be less than detectable, except for a very small quantity of lead-210 (an alpha emitter), which is a naturally occurring isotope of lead. Based on the pristine nature of lead, a proposed free release criterion for lead was developed based on a statistical null hypothesis approach. The free release criterion compares the natural background count of a clean lead standard with the natural background count of a sample. When the sample background count cannot be distinguished as different from the standard background count at the 95% confidence level, then the sample is considered radiologically clean.
Date: December 31, 1994
Creator: Losinski, S.J.
Partner: UNT Libraries Government Documents Department

Originating super-strong liquid crystalline polymers (SSLCPs). Final report

Description: The work at the University of North Carolina at Chapel Hill focused on the experimental characterization of ring mobility in labeled polyaramides with deuterium Nuclear Magnetic Resonance (NMR). Los Alamos National Laboratory prepared the deuterium-labeled analogs of Super-Strong (SS), Liquid Crystalline Polymers (LCPs) and oligomers. These materials were studied to ascertain the influence of substituent size (at the diacid moiety) on the mobility of the labeled diamine. The results are currently being finalized for publication.
Date: December 31, 1994
Partner: UNT Libraries Government Documents Department

[Photochemistry of intermolecular C-H bond activation reactions]. Progress report, [September 15, 1994--March 15, 1995]

Description: Since the last progress report (March 15, 1994), attention was paid to the solution photochemistry of (HBPz*{sub 3})Rh(CO){sub 2} (Pz* = 3,5-dimethylpyrazolyl) at different excitation wavelengths and in various hydrocarbon solvents (n-pentane). Absolute quantum efficiencies were obtained for the intermolecular C-H bond activation at different wavelengths and temperatures. Results indicate that there are two excited states with different reactivities and two reaction channels. The intermediate that is highly reactive toward hydrocarbon C-H bonds is probably the monocarbonyl (HBPz*{sub 3})Rh(CO) species. Related studies are being carried out on tungsten(IV) eight-coordinate-chelate complexes.
Date: December 15, 1994
Creator: Lees, A.J.
Partner: UNT Libraries Government Documents Department

Visualization of parallel molecular dynamics simulation on a remote visualization platform

Description: Visualization requires high performance computers. In order to use these shared high performance computers located at national centers, the authors need an environment for remote visualization. Remote visualization is a special process that uses computing resources and data that are physically distributed over long distances. In their experimental environment, a parallel raytracer is designed for the rendering task. It allows one to efficiently visualize molecular dynamics simulations represented by three dimensional ball-and-stick models. Different issues encountered in creating their platform are discussed, such as I/O, load balancing, and data distribution.
Date: September 1, 1994
Creator: Lee, T.Y.; Raghavendra, C.S. & Nicholas, J.B.
Partner: UNT Libraries Government Documents Department

XRF and leaching characterization of waste glasses derived from wastewater treatment sludges

Description: Purpose of this study was to investigate use of XRF (x-ray fluorescence spectrometry) as a near real-time method to determine melter glass compositions. A range of glasses derived from wastewater treatment sludges associated with DOE sites was prepared. They were analyzed by XRF and wet chemistry digestion with atomic absorption/inductively coupled emission spectrometry. Results indicated good correlation between these two methods. A rapid sample preparation and analysis technique was developed and demonstrated by acquiring a sample from a pilot-scale simulated waste glass melter and analyzing it by XRF within one hour. From the results, XRF shows excellent potential as a process control tool for waste glass vitrification. Glasses prepared for this study were further analyzed for durability by toxicity characteristic leaching procedure and product consistency test and results are presented.
Date: December 1, 1994
Creator: Ragsdale, R.G., Jr
Partner: UNT Libraries Government Documents Department