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Radium-Barium Separation Process: Part 2 - Chromate Fractionation Procedures

Description: Abstract: A comprehensive study was made of various fractionation systems for the fractional separation of barium-radium mixtures. The most efficient and simplest fractionation scheme was chosen on the basis of the thermodynamics of separating the constituents of mixed crystals and of the combining fractions in a system of repeating composition. This scheme was applied to the separation of barium and radium by utilizing the countercurrent batch fractionation of the chromates. The chromate procedure was evaluated by a comparison with the classic methods which employ the fractional crystallization of the halides. The chromate method is more practical on the basis of radium enrichment per fractionation step, control of precipitating conditions, simplicity, and speed of operation.
Date: April 1, 1951
Creator: Salutsky, Murrell Leon; Stites, J. G. & Joy, E. F.
Partner: UNT Libraries Government Documents Department


Description: The mechanisms involved in fractionation as measured in samples obtained early from drone planes during the cloud rise or from manned aircraft a few hours later are discussed. A key problem in fractionation is the formation of the precipitate in the cloud, and an attcmpt is made to describe this mechanism. (W.D.M.)
Date: November 16, 1953
Creator: Magee, J.L.
Partner: UNT Libraries Government Documents Department

The Fractionation of Loblolly Pine Woodchips Into Pulp For Making Paper Products

Description: The overall goal of the project was to test the PureVision biomass fractionation technology for making pulp from loblolly pine. A specific goal was to produce a pulp product that is comparable to pulp produced from the kraft process, while reducing the environmental effects of the kraft process, known to be a highly pollutant process. The overall goal of the project was met by using the biomass fractionation concept for making pulp product. This proof-of-concept study, done with Southern pine pinchips as feedstock, evaluated NaOH concentration and residence time as variables in single-stage cocurrent pulping process. It can be concluded that 1% NaOH is adequate for effective delignification using the PureVision process; this is about ⅓ of that used in the kraft process. Also, the PureVision process does not use sulfur-based chemicals such as N2S and hence, is environmentally more benign.
Date: November 30, 2006
Creator: Kiran Kadam, PhD
Partner: UNT Libraries Government Documents Department

Laboratory Experiments Bearing on the Origin and Evolution of Olivine-rich Chondrules

Description: Evaporation rates of K2O, Na2O, and FeO from chondrule-like liquids and the associated potassium isotopic fractionation of the evaporation residues were measured to help understand the processes and conditions that affected the chemical and isotopic compositions of olivine-rich Type IA and Type IIA chondrules from Semarkona. Both types of chondrules show evidence of having been significantly or totally molten. However, these chondrules do not have large or systematic potassium isotopic fractionation of the sort found in the laboratory evaporation experiments. The experimental results reported here provide new data regarding the evaporation kinetics of sodium and potassium from a chondrule-like melt and the potassium isotopic fractionation of evaporation residues run under various conditions ranging from high vacuum to pressures of one bar of H2+CO2, or H2, or helium. The lack of systematic isotopic fractionation of potassium in the Type IIA and Type IA chondrules compared with what is found in the vacuum and one-bar evaporation residues is interpreted as indicating that they evolved in a partially closed system where the residence time of the surrounding gas was sufficiently long for it to have become saturated in the evaporating species and for isotopic equilibration between the gas and the melt. A diffusion couple experiment juxtaposing chondrule-like melts with different potassium concentrations showed that the diffusivity of potassium is sufficiently fast at liquidus temperatures (DK>2-10-4cm2/s at 1650-C) that diffusion-limited evaporation cannot explain why, despite their having been molten, the Type IIA and Type IA chondrules show no systematic potassium isotopic fractionation.
Date: June 24, 2011
Creator: Richter, Frank M.; Mendybaev, Ruslan A.; Christensen, John N.; Ebel, Denton & Gaffney, Amy
Partner: UNT Libraries Government Documents Department


Description: Gamma-ray multiplicities have been measured as a function of the light-fragment atomic number Z{sub 3} for the above reactions. The events associated with sequential fission of the heavy fragment were distinguished from binary events by means of a triple coincidence. The failure of the measured y-multiplicities for deep-inelastic collisions to rise with decreasing Z{sub 3}, according to the rigid-rotation limit, appears more likely to be associated with a selective population of the low Z fragments by the lower {ell}-waves rather than to an incomplete relaxation of the rotational energy.
Date: October 1, 1977
Creator: Aleonard, M.M.; Wozniak, G.J.; Glassel, P.; Deleplanque, M.A.; Diamond, R.M.; Moretto, L.G. et al.
Partner: UNT Libraries Government Documents Department

Clean fractionation of biomass

Description: The US DOE Alternative Feedstocks (AF) program is forging new links between the agricultural community and the chemicals industry through support of research and development (R&D) that uses green feedstocks to produce chemicals. The program promotes cost-effective industrial use of renewable biomass as feedstocks to manufacture high-volume chemical building blocks. Industrial commercialization of such processes would stimulate the agricultural sector by increasing the demand of agricultural and forestry commodities. A consortium of five DOE national laboratories has been formed with the objectives of providing industry with a broad range of expertise and helping to lower the risk of new process development through federal cost sharing. The AF program is conducting ongoing research on a clean fractionation process, designed to convert biomass into materials that can be used for chemical processes and products. The focus of the clean fractionation research is to demonstrate to industry that one technology can successfully separate all types of feedstocks into predictable types of chemical intermediates.
Date: September 1, 1995
Partner: UNT Libraries Government Documents Department

Stability of Trilateral Forces: II, Large Symmetric Force

Description: For large symmetric offensive forces, as for small, at few weapons per missile all forces are reserved, costs are constant, and configurations are stable. At many weapons permissile, no weapons are reserved, first strike costs decrease, fractionation is attractive, and stability degrades. These results a due to symmetries that would not be degraded by additional symmetric opponents.
Date: September 17, 1998
Creator: Canavan, G. H.
Partner: UNT Libraries Government Documents Department

Oxygen isotope fractionation in the vacuum ultraviolet photodissociation of carbon monoxide: Wavelength, pressure and temperature dependency.

Description: Several absorption bands exist in the VUV region of Carbon monoxide (CO). Emission spectra indicate that these bands are all predissociative. An experimental investigation of CO photodissociation by vacuum ultraviolet photons (90 to 108 nm; ~13 to 11 eV) from the Advanced Light Source Synchrotron and direct measurement of the associated oxygen isotopic composition of the products are presented here. A wavelength dependency of the oxygen isotopic composition in the photodissociation product was observed. Slope values (δ'{sup 18}O/ δ'{sup 17}O) ranging from 0.76 to 1.32 were observed in oxygen three-isotope space (δ'{sup 18}O vs. δ'{sup 17}O) which correlated with increasing synchrotron photon energy, and indicate a dependency of the upper electronic state specific dissociation dynamics (e.g., perturbation and coupling associated with a particular state). An unprecedented magnitude in isotope separation was observed for photodissociation at the 105 and 107 nm synchrotron bands and are found to be associated with accidental predissociation of the vibrational states ({nu} = 0 and 1) of the upper electronic state E{sup 1}Π. For each synchrotron band, a large (few hundred per mil) extent of isotopic fractionation was observed and the range of fractionation is a combination of column density and exposure time. A significant temperature dependency in oxygen isotopic fractionation was observed, indicating a rotational level dependency in the predissociation process.
Date: January 3, 2012
Creator: Chakraborty, Subrata; Davis, Ryan; Ahmed, Musahid; Jackson, Teresa L. & Thiemens, Mark H.
Partner: UNT Libraries Government Documents Department

Chemical and isotopic characteristics of the coso east flankhydrothermal fluids: implications for the location and nature of the heatsource

Description: Fluids have been sampled from 9 wells and 2 fumaroles fromthe East Flank of the Coso hydrothermal system with a view toidentifying, if possible, the location and characteristics of the heatsource inflows into this portion of the geothermal field. Preliminaryresults show that there has been extensive vapor loss in the system, mostprobably in response to production. Wells 38A-9, 51-16 and 83A-16 showthe highest CO2-CO-CH4-H2 chemical equilibration temperatures, rangingbetween 300-340oC, and apart from 38A-9, the values are generally inaccordance with the measured temperatures in the wells. Calculatedtemperatures for the fractionation of 13C between CO2 and CH4 are inexcess of 400oC in fluids from wells 38A-9, 64-16-RD2 and 51A-16,obviously pointing to equilibrium conditions from deeper portions of thereservoir. Given that the predominant reservoir rock lithologies in theCoso system are relatively silicic (granitic to dioritic), the isotopicsignatures appear to reflect convective circulation and equilibrationwithin rocks close to the plastic-brittle transition. 3He/4He signatures,in conjunction with relative volatile abundances in the Coso fluids,point to a possibly altered mantle source for the heat sourcefluids.
Date: January 8, 2007
Creator: Christenson, B.W.; Kennedy, B.M.; Adams, M.C.; Bjornstad, S.C. & Buck, C.
Partner: UNT Libraries Government Documents Department


Description: The International Organization for Standardization (ISO) has published a Guide to the expression of Uncertainty in Measurement (GUM). The IUPAC Commission on Isotopic Abundance and Atomic Weight (CIAAW) began attaching uncertainty limits to their recommended values about forty years ago. CIAAW's method for determining and assigning uncertainties has evolved over time. We trace this evolution to their present method and their effort to incorporate the basic ISO/GUM procedures into evaluations of these uncertainties. We discuss some dilemma the CIAAW faces in their present method and whether it is consistent with the application of the ISO/GUM rules. We discuss the attempt to incorporate variations in measured isotope ratios, due to natural fractionation, into the ISO/GUM system. We make some observations about the inconsistent treatment in the incorporation of natural variations into recommended data and uncertainties. A recommendation for expressing atomic weight values using a tabulated range of values for various chemical elements is discussed.
Date: July 23, 2007
Creator: Holden, N. E.
Partner: UNT Libraries Government Documents Department

Uranium-lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

Description: Uranium-lead ratios (commonly represented as {sup 238}U/{sup 204}Pb = {mu}) calculated for the sources of martian basalts preserve a record of petrogenetic processes that operated during early planetary differentiation and formation of martian geochemical reservoirs. To better define the range of {mu} values represented by the source regions of martian basalts, we completed U-Pb elemental and isotopic analyses on whole rock, mineral and leachate fractions from the martian meteorite Queen Alexandra Range 94201 (QUE 94201). The whole rock and silicate mineral fractions have unradiogenic Pb isotopic compositions that define a narrow range ({sup 206}Pb/{sup 204}Pb = 11.16-11.61). In contrast, the Pb isotopic compositions of weak HCl leachates are more variable and radiogenic. The intersection of the QUE 94201 data array with terrestrial Pb in {sup 206}Pb/{sup 204}Pb-{sup 207}Pb/{sup 204}Pb-{sup 208}Pb/{sup 204}Pb compositional space is consistent with varying amounts of terrestrial contamination in these fractions. We calculate that only 1-7% contamination is present in the purified silicate mineral and whole rock fractions, whereas the HCl leachates contain up to 86% terrestrial contamination. Despite the contamination, we are able to use the U-Pb data to determine the initial {sup 206}Pb/{sup 204}Pb of QUE 94201 (11.086 {+-} 0.008) and calculate the {mu} value of the QUE 94201 mantle source to be 1.823 {+-} 0.008. This is the lowest {mu} value calculated for any martian basalt source, and, when compared to the highest values determined for martian basalt sources, indicates that {mu} values in martian source reservoirs vary by at least 100%. The range of source {mu} values further indicates that the {mu} value of bulk silicate Mars is approximately three. The amount of variation in the {mu} values of the mantle sources ({mu} {approx} 2-4) is greater than can be explained by igneous processes involving silicate phases alone. We suggest the possibility that ...
Date: December 22, 2006
Creator: Gaffney, A M; Borg, L E & Connelly, J N
Partner: UNT Libraries Government Documents Department

Kinetic Isotopic Fractionation During Diffusion of Ionic Speciesin Water

Description: Experiments specifically designed to measure the ratio of the diffusivities of ions dissolved in water were used to determine D{sub Li}/D{sub K}, D{sub 7{sub Li}}/D{sub 6{sub Li}}, D{sub 25{sub Mg}}/D{sub 24{sub Mg}}, D{sub 26{sub Mg}}/D{sub 25{sub Mg}}, and D{sub 37{sub Cl}}/D{sub 35{sub Cl}}. The measured ratio of the diffusion coefficients for Li and K in water (D{sub Li}/D{sub K} = 0.6) is in good agreement with published data, providing evidence that the experimental design being used resolves the relative mobility of ions with adequate precision to also be used for determining the fractionation of isotopes by diffusion in water. In the case of Li we found measurable isotopic fractionation associated with the diffusion of dissolved LiCl (D{sub 7{sub Li}}/D{sub 6{sub Li}} = 0.99772 {+-} 0.00026). This difference in the diffusion coefficient of {sup 7}Li compared to {sup 6}Li is significantly less than reported in an earlier study, a difference we attribute to the fact that in the earlier study Li diffused through a membrane separating the water reservoirs. Our experiments involving Mg diffusing in water found no measurable isotopic fractionation (D{sub 25{sub Mg}}/D{sub 24{sub Mg}} = 1.00003 {+-} 0.00006). Cl isotopes were fractionated during diffusion in water (D{sub 37{sub Cl}}/D{sub 35{sub Cl}} = 0.99857 {+-} 0.00080) whether or not the co-diffuser (Li or Mg) was isotopically fractionated. The isotopic fractionation associated with the diffusion of ions in water is much smaller than values we found previously for the isotopic fractionation of Li and Ca isotopes by diffusion in molten silicate liquids. A major distinction between water and silicate liquids is that water, being a polar liquid, surrounds dissolved ions with hydration shells, which very likely play an important but still poorly understood role in reducing isotopic fractionation associated with diffusion.
Date: June 9, 2005
Creator: Richter, Frank M.; Mendybaev, Ruslan A.; Christensen, John; Hutcheon, Ian D.; Williams, Ross W.; Sturchio, Neil C. et al.
Partner: UNT Libraries Government Documents Department


Description: Phytoplankton activity in an oligotrophic environment was studied on six cruises over a 14-month period. Phytoplankton biomass and productivity displayed considerable temporal variability despite the relative constancy of the physical and chemical environment. No evidence of seasonality or diurnal variability in phytoplankton biomass was observed. Annual average (+ s.d.) depth-integrated values (0-260 m) for chlorophyll a, phaeopigment, ATP, and primary productivity were 24.55 + 10.31 mg {center_dot} m{sup -2}, 11.81 + 7.20 mg {center_dot} m{sup -2}, 3.00 + 1.78 mg {center_dot} m{sup -2}, and 8.79 + 7.82 mg C {center_dot} m{sup -2}, h{sup -1}, respectively; over the year these parameters were seen to vary over ranges of 3X, 6X, 10X, and 26X, respectively. The mean depths of the chlorophyll and phaeopigment maxima were 85 + 9 m and 95 + 11 m, respectively; the pheopigment maximum was always located at or below that of chlorophyll. Size fractionation studies showed that at this oceanic station about 80% of the phytoplankton biomass occurred in the < 5 {micro}m fraction. Low ambient nutrient levels were typical at the depth of the chlorophyll maximum, indicating that nutrient assimilation was actively occurring in that layer. Elevated nutrient levels were typical at the deeper phaeopigment maximum layer. The results of sinking rate and size fractionation experiments, together with evidence of physiological viability in this layer suggest that phytoplankton sinking and possibly its association with the nutrient regime influence the accumulation of biomass in this region. Productivity biomass ratios (mg carbon {center_dot} mg chlorophyll a{sup -1} {center_dot} h{sup -1}) were consistently low and indicative of strong nutrient limitation. Variations in phytoplankton biomass did not account (p > 0.10) for the high variability in photosynthetic activity among the six site visits; neither did the slopes or upper depth limits of the nitrate or phosphate gradients (as indicators of ...
Date: July 1, 1980
Creator: Bienfang, P.K. & Szyper, J.P.
Partner: UNT Libraries Government Documents Department

Phosphorus Retention and Fractionation in Masonry Sand and Light Weight Expanded Shale Used as Substrate in a Subsurface Flow Wetland

Description: Constructed wetlands are considered an inefficient technology for long-term phosphorus (P) removal. The P retention effectiveness of subsurface wetlands can be improved by using appropriate substrates. The objectives of this study were to: (i) use sorption isotherms to estimate the P sorption capacity of the two materials, masonry sand and light weight expanded shale; (ii) describe dissolved P removal in small (2.7 m3) subsurface flow wetlands; (iii) quantify the forms of P retained by the substrates in the pilot cells; and (iv) use resulting data to assess the technical and economic feasibility of the most promising system to remove P. The P sorption capacity of masonry sand and expanded shale, as determined with Langmuir isotherms, was 60 mg/kg and 971 mg/kg respectively. In the pilot cells receiving secondarily treated wastewater, cells containing expanded shale retained a greater proportion of the incoming P (50.8 percent) than cells containing masonry sand (14.5 percent). After a year of operation, samples were analyzed for total P (TP) and total inorganic P (TIP). Subsamples were fractionated into labile-P, Fe+Al-bound P, humic-P, Ca+Mg-bound P, and residual-P. Means and standard deviations of TP retained by the expanded shale and masonry sand were 349 + 169 and 11.9 + 18.6 mg/kg respectively. The largest forms of P retained by the expanded shale pilot cells were Fe+Al- bound P (108 mg/kg), followed by labile-P (46.7 mg/kg) and humic-P (39.8). Increases in the P forms of masonry sand were greatest in labile-P (7.5 mg/kg). The cost of an expanded shale wetland is within the range of costs conventional technologies for P removal. Accurate cost comparisons are dependent upon expansion capacity of the system under consideration. Materials with a high P sorption capacity also have potential for enhancing P removal in other constructed wetland applications such as stormwater wetlands and wetlands ...
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Date: August 2002
Creator: Forbes, Margaret G.
Partner: UNT Libraries

Update to modeling soil selenium concentrations in the shallow soil profile at Kesterson Reservoir Merced County, California

Description: A mass balance model was developed to predict concentrations of water-extractable selenium in surface and subsurface soil by extrapolating the trend observed from 6 years of soil monitoring data collected at Kesterson Reservoir. Correlations between observed and calculated concentrations indicate that the major trends and year-to-year variations are well represented with the model. Results from this exercise were then used, under three climatic scenarios, to simulate the evolution of the soluble selenium inventory 25 years into the future. Based on these simulations, we expect that the availability of the soluble selenium inventory has most likely reached peak levels, and is now declining. However, year-to-year climatic variations may influence the rate of decline, and occasionally reverse this prevailing trend.
Date: January 1, 1996
Creator: Wahl, C. & Benson, S. M.
Partner: UNT Libraries Government Documents Department

A study of over production and enhanced secretion of enzymes. Quarterly report 1

Description: The current project is concerned with the over-production and enhanced secretion of PPO, cellulase and lignin peroxidase. The project is divided into two segments: over-production of lignocellulolytic enzymes by genetic engineering methodologies and hyper-production and enhanced secretion of these enzymes by biochemical/electron microscopical techniques. The former approach employs recombinant DNA procedures, ligation of appropriate nuclease generated DNA fragments into a vector and the subsequent transformation of Escherichia coli to yield E. coli harboring a C. versicolor DNA insert. The biochemistry/electron microscopical method involves substrate induction and the time-dependent addition of respiration and PPO inhibitors to elevate C.versicolor`s ability to synthesize and secrete lignocellulosic enzymes. In this connection, cell fractionation/kinetic analysis, TEM immunoelectron microscopic localization and TEM substrate localization of PPO are being employed to assess the route of secretion. Both approaches will culminate in the batch culture of either E. coli or C. versicolor, in a fermentor with the subsequent development of rapid isolation and purification procedures to yield elevated quantities of pure lignocellulosic enzymes. During the past year, research effort were directed toward determining the route of polyphenol oxidase (PPO) secretion by the wood-decay fungus, Coriolus versicolor. In addition, research activities were continued to over-produce and to purify PPO as well as define the time-dependent intra- and extra-cellular appearances of C. versicolor ligninases and cellulases.
Date: December 28, 1992
Creator: Dashek, W.V.
Partner: UNT Libraries Government Documents Department

A study of over-production and enhanced secretion of enzymes. Quarterly report 2

Description: This project is concerned with the over-production of ligno-cellulolytic enzymes which are relevant to the paper-pulp industry and agricultural community. Since ligno-cellulosics are components of wood, the project involves the forest, a renewable energy resource. Attention is focused on the following: over-production of polyphenol oxidase; establishment of the route of polyphenol oxidase secretion; regulation of polyphenol oxidase secretion; purification of extracellular oxidase.
Date: April 8, 1993
Creator: Dashek, W.V.
Partner: UNT Libraries Government Documents Department

Chem-Prep PZT 95/5 for Neutron Generator Applications: Powder Fractionation Study of Production-Scale Powders

Description: The Materials Chemistry Department 1846 has developed a lab-scale chem-prep process for the synthesis of PNZT 95/5, referred to as the ''SP'' process (Sandia Process). This process (TSP) has been successfully transferred to and scaled-up by Department 14192 (Ceramics and Glass Department), producing the larger quantities of PZT powder required to meet the future supply needs of Sandia for neutron generator production. The particle size distributions of TSP powders routinely have been found to contain a large particle size fraction that was absent in development (SP) powders. This SAND report documents experimental studies focused on characterizing these particles and assessing their potential impact on material performance. To characterize these larger particles, fractionation of several TSP powders was performed. The ''large particle size fractions'' obtained were characterized by particle size analysis, SEM, and ICP analysis and incorporated into compacts and sintered. Large particles were found to be very similar in structure and composition as the bulk of the powder. Studies showed that the large-size fractions of the powders behave similarly to the non-fractionated powder with respect to the types of microstructural features once sintered. Powders were also compared that were prepared using different post-synthesis processing (i.e. differences in precipitate drying). Results showed that these powders contained different amounts and sizes of porous inclusions when sintered. How this affects the functional performance of the PZT 95/5 material is the subject of future investigations.
Date: June 1, 2003
Partner: UNT Libraries Government Documents Department

Salt effects on isotope partitioning and their geochemical implications: An overview

Description: Essential to the use of stable isotopes as natural tracers and geothermometers is the knowledge of equilibrium isotope partitioning between different phases and species, which is usually a function of temperature only. The one exception known to date is oxygen and hydrogen isotope fractionation between liquid water and other phases (steam, gases, minerals), which changes upon the addition of salts to water, i.e., the isotope salt salt effect. Our knowledge of this effect, the difference between activity and composition (a-X) of isotopic water molecules in salt solutions, is very limited and controversial, especially at elevated temperatures. For the last several years, we have been conducting a detailed, systematic experimental study at Oak Ridge National Laboratory to determine the isotope salt effects from room temperature to elevated temperatures (currently to 500{degree}C). From this effort, a simple, coherent picture of the isotope salt effect is emerging, that differs markedly from the complex results reported in the literature. In this communication, we present an overview on the isotope salt effect, obtained chiefly from our study. Observed isotope salt effects in salt solutions are significant even at elevated temperatures. The importance and implications of the isotope salt effect for isotopic studies of brine-dominated systems are also discussed in general terms.
Date: January 1, 1996
Creator: Horita, J.; Cole, D.R. & Fortier, S.M.
Partner: UNT Libraries Government Documents Department

Fine coal fractionation using a magnetohydrostatic separation process CRADA 91-003. Final report

Description: The magnetohydrostatic separation (MHS) process uses a magnetic fluid which has the ability to float a submerged particle in a magnetic field. The objective of this project was to develop a technique for laboratory gravity fractionation of coal using MHS.
Date: October 31, 1992
Creator: Cho, Heechan & Killmeyer, R.P.
Partner: UNT Libraries Government Documents Department

Investigation into the fractionation of refrigerant blends. Quarterly technical report, October 1--December 31, 1994

Description: While the use of refrigerant blends both from analytical predictions and system test results appear to offer certain performance, capacity, design and operational advantages, there are significant possible service and operational issues that are raised by the use of blends. Many of these issues occur due to the fractionation of the blends. Fractionation can result in increased safety hazards if during leakage the more volatile components are flammable, and must be considered in the design of the heat exchanger, expansion valves and other system components. Fractionation can occur during charging of the system or during leakage in selected two-phase components, as well as due to the different miscibility of the blend component refrigerants and the selected compressor lubricant. The objective of this ARTI-sponsored program is to conduct analytical and laboratory tests aimed at understanding these issues, developing approaches or techniques to predict these effects and/or overcome these potential problems, and conveying to the industry safe and reliable approaches.
Date: January 1, 1995
Creator: Biancardi, F.R.
Partner: UNT Libraries Government Documents Department