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Biomimetic thin film deposition

Description: Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.
Date: September 1, 1995
Creator: Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L. et al.
Partner: UNT Libraries Government Documents Department

The effects of thermal cycling on the physical and mechanical properties of [NZP] ceramics

Description: The [NZP] ceramics, sodium zirconium phosphate and its crystal structure analogs, are noted for their very low thermal expansion characteristics. What has not been widely studied is the effect of thermal cycling on physical and mechanical properties. Two [NZP] compositional series were selected (Ba{sub 1+x}Zr{sub 4}P{sub 6{minus}2x}Si{sub 2x}O{sub 24} and Ca{sub 1{minus}x}Sr{sub x}Zr{sub 4}P{sub 6}O{sub 24}) that exhibit varying bulk thermal expansion from positive to negative and varying degrees of thermal expansion anisotropy. The effect of thermal cycling, to 1,250 C, on the bulk thermal expansion and flexural strength of these ceramics is discussed in relationship to changes in density, thermal expansion anisotropy and microstructure.
Date: December 31, 1994
Creator: Jackson, T.B.; Limaye, S.Y. & Porter, W.D.
Partner: UNT Libraries Government Documents Department

Monte Carlo Simulations of Phosphate Polyhedron Connectivity in Glasses

Description: Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dimensional exchange and double-quantum NMR experiments of phosphate glasses. These Monte Carlo simulations demonstrate that the polyhedron connectivity is best described by a random distribution in lithium phosphate and calcium phosphate glasses.
Date: December 21, 1999
Creator: ALAM,TODD M.
Partner: UNT Libraries Government Documents Department

Digital electronic bone growth stimulator

Description: The present invention relates to the electrical treatment of biological tissue. In particular, the present invention discloses a device that produces discrete electrical pulse trains for treating osteoporosis and accelerating bone growth. According to its major aspects and broadly stated, the present invention consists of an electrical circuit configuration capable of generating Bassett-type waveforms shown with alternative signals provide for the treatment of either fractured bones or osteoporosis. The signal generator comprises a quartz clock, an oscillator circuit, a binary divider chain, and a plurality of simple, digital logic gates. Signals are delivered efficiently, with little or no distortion, and uniformly distributed throughout the area of injury. Perferably, power is furnished by widely available and inexpensive radio batteries, needing replacement only once in several days. The present invention can be affixed to a medical cast without a great increase in either weight or bulk. Also, the disclosed stimulator can be used to treat osteoporosis or to strengthen a healing bone after the cast has been removed by attaching the device to the patient`s skin or clothing.
Date: January 1, 1993
Creator: Kronberg, J.W.
Partner: UNT Libraries Government Documents Department

Prototype development and testing of ultrafine grain NZP ceramics. Quarterly progress report {number_sign}4, January 28, 1996--April 27, 1996

Description: Caterpillar Inc. continues to develop a slip casting procedure for CMZP (CaMgZr phosphate) exhaust portliners for diesel engines. ZnO was used as additive. Tubes have been cast and fired and initial properties look excellent. 40 lbs of CMZP powder are being prepared for Caterpillar to complete the slip casting of 90 degree elbows.
Date: May 24, 1996
Creator: Brown, J.J.
Partner: UNT Libraries Government Documents Department

High temperature alkali corrosion of dense SiC and Si{sub 3}N{sub 4} coated with CMZP and Mg-DOPED Al{sub 2}TiO{sub 5} in coal gas. Quarterly progress report No. 6, October 1, 1995--December 31, 1995

Description: High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. Non-oxide ceramics, such as SiC and Si{sub 3}N{sub 4}, are applied in HITAF systems for their well-known and desirable high temperature thermal and mechanical properties. However, these materials are prone to rapid corrosion under some types of high temperature coal combustion conditions. The objective of this research is to apply CMZP and Mg- Al{sub 2}TiO{sub 5} as coatings to SiC to improve corrosion resistance under coal combustion atmospheres as well as to improve high temperature mechanical properties. The research will not only develop and characterize CMZP and Mg-Al{sub 2}TiO{sub 5} coatings but will also strive to expand the existing knowledge of the mechanism of coal combustion corrosion of SiC in the temperature range of 1000- 4000{degrees}C.
Date: December 31, 1995
Creator: Yang, S. & Brown, J.J.
Partner: UNT Libraries Government Documents Department

Prototype development and testing of ultrafine grain NZP ceramics. Quarterly technical progress report No. 3, October 28, 1995--January 27, 1996

Description: Caterpillar has been developing advanced low-heat-rejection (LHR) engine designs because by insulating the combustion chamber components for reduced heat rejection, improved fuel economy and emission reduction can be achieved. The insulation eliminates heat loss during the closed portion of the cycle and increases the combustion temperature. Increased combustion temperatures improve emissions by reducing the amount of particulate or smoke. The higher combustion temperatures also provide additional energy to drive a turbocharger that, in turn, improves the overall efficiency of the engine system and results in increased fuel economy.
Date: February 8, 1996
Creator: Brown, J.J.
Partner: UNT Libraries Government Documents Department

Oxidation resistant coatings for ceramic matrix composite components

Description: Corrosion resistant Ca{sub 0.6}Mg{sub 0.4}Zr{sub 4}(PO{sub 4}){sub 6} (CMZP) and Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}(PO{sub 4}){sub 6} (CS-50) coatings for fiber-reinforced SiC-matrix composite heat exchanger tubes have been developed. Aqueous slurries of both oxides were prepared with high solids loading. One coating process consisted of dipping the samples in a slip. A tape casting process has also been created that produced relatively thin and dense coatings covering a large area. A processing technique was developed, utilizing a pre-sintering step, which produced coatings with minimal cracking.
Date: November 1, 1998
Creator: Vaubert, V.M.; Stinton, D.P. & Hirschfeld, D.A.
Partner: UNT Libraries Government Documents Department

Electron-irradiation-induced crystallization of amorphous orthophosphates

Description: Amorphous LaPO{sub 4}, EuPO{sub 4}, GdPO{sub 4}, ScPO{sub 4}, and fluorapatite [Ca{sub 5}(PO{sub 4}){sub 3}F] were irradiated by electron beam in a TEM. Irradiations were done at -150 to 300 C, 80 to 200 keV, and current densities from 0.3 to 16 A/cm{sup 2}. In all cases, the materials crystallized to form a randomly oriented polycrystalline assemblage. Crystallization is driven dominantly by inelastic processes, although ballistic collisions with target nuclei can be important above 175 keV, particularly in apatite. Using a high current density, crystallization is so fast that continuous lines of crystallites can be ``drawn`` on the amorphous matrix.
Date: December 1, 1996
Creator: Meldrum, A.; Ewing, R.C. & Boatner, L.A.
Partner: UNT Libraries Government Documents Department

Prototype development and testing of ultrafine grain NZP ceramics. Final report, July 28, 1995--April 27, 1997

Description: The goal of this project was to demonstrate that a new low-expanding ceramic (Ca{sub 0.6},Mg{sub 0.4})Zr{sub 4}(PO{sub 4}){sub 6}, hereafter referred to as CMZP, could be used as an exhaust manifold liner in off-road diesel engines and provide improved engine efficiency (by permitting higher engine operating temperature). This study has successfully demonstrated this improvement and further engine testing (and possible manufacturing) is presently underway at Caterpillar Inc. Laboratories. Basically this program involved two subcontracts: one to Virginia Tech to develop sintering procedures for CMZP, and one to Caterpillar, Inc. to develop slip casting procedures for CMZP. Nearly 100kg of CMZP were prepared by MATVA, Inc. and Virginia Tech for use by Caterpillar. Virginia Tech developed detailed sintering procedures for CMZP and Caterpillar developed slip casting procedures and manufactured several exhaust manifold elbows. These elbows have been cast into prototype cylinder heads and have been shown to be acceptable replacements for metal manifolds. (Caterpillar advises that a new component may require up to 6 years of testing and qualification before acceptance as standard diesel engine part).
Date: August 4, 1997
Creator: Brown, J.J.
Partner: UNT Libraries Government Documents Department

Lost circulation control materials. Progress report

Description: Work in FY 94 continued to investigate the use of calcium phosphate cements as lost circulation control materials for geothermal wells. The calcium phosphate cements were produced by reacting calcium aluminate cement with sodium phosphate compounds. Pumpable formulations with thickening times up to two hours at temperatures between 25 to 90{degrees}C were developed and characterized. The materials showed rapid set behaviour, early strength development, low permeability and acceptable durability in hydrothermal environments. Strengths up to 4 MPa were achieved four hours after mixing and water permeabilities were of the order of 10{sup -9} to 10{sup -7} cm/s at 24 hours. Partial replacement of calcium aluminate cement with ground granulated blast furnace slag was found to reduce the amount of borax retarder required to maintain pumpability at elevated temperatures and pressures.
Date: January 1994
Creator: Allan, M. L. & Kukacka, L. E.
Partner: UNT Libraries Government Documents Department

Monte Carlo simulations of phosphate polyhedron connectivity in glasses

Description: Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dimensional exchange and double-quantum NMR experiments of phosphate glasses. These Monte Carlo simulations demonstrate that the polyhedron connectivity is best described by a random distribution in lithium phosphate and calcium phosphate glasses.
Date: January 1, 2000
Creator: ALAM,TODD M.
Partner: UNT Libraries Government Documents Department

Effects of soluble organic complexants and their degradation products on the removal of selected radionuclides from high-level waste. Part II: Distributions of Sr, Cs, Tc, and Am onto 32 absorbers from four variations of Hanford tank 101-SY simulant solution

Description: Many of the radioactive waste storage tanks at U.S. Department of Energy facilities contain organic compounds that have been degraded by radiolysis and chemical reactions during decades of storage. In this second part of our three-part investigation of the effects of soluble organic complexants and their degradation products, we measured the sorption of strontium, cesium, technetium, and americium onto 32 absorbers that offer high sorption of these elements in the absence of organic complexants. The four solutions tested were (1) a simulant for a 3:1 dilution of Hanford Tank 101-SY contents that initially contained ethylenediaminetetraacetic acid (EDTA), (2) this simulant after gamma-irradiation to 34 Mrads, (3) the unirradiated simulant after treatment with a hydrothermal organic-destruction process, and (4) the irradiated simulant after hydrothermal processing. For each of 512 element/absorber/solution combinations, we measured distribution coefficients (Kds) twice for each period for dynamic contact periods of 30 min, 2 h, and 6 h to obtain information about sorption kinetics. On the basis of our 3,072 measured Kd values, the sorption of strontium and americium is significantly decreased by the organic components of the simulant solutions, whereas the sorption of cesium and technetium appears unaffected by the organic components of the simulant solutions.
Date: April 1, 1995
Creator: Marsh, S.F.; Svitra, Z.V. & Bowen, S.M.
Partner: UNT Libraries Government Documents Department

Powder-based synthesis of nanocrystalline material components for structural application. Final report

Description: Hydroxiapate spray coatings and substrates for implant production as well as multilayered metal ceramic coatings from nanocrystalline materials are a subject of the investigation. The work aims at the improvement of quality of said objects. This study has investigated the processes of hydroxiapatite powder production. Sizes, shapes and relief of initial HA powder surface are analyzed using SEM and TEM. Modes of HA plasma spraying on a substrate from titanium and associated compositions of traditional and nanocrystalline structure are optimized. The quality of the sprayed samples are studied using X-ray phase analysis and metallographic analysis. The results of investigations of bioceramic coating spraying on titanium are theoretically generalized, taking into account obtained experimental data. The results of investigations of ion-beam technology are presented for spraying multilayered coatings consisting of alternating metal-ceramic layers of nanocrystalline structure.
Date: December 1, 1998
Creator: Ilyuschenko, A.F.; Ivashko, V.S. & Okovity, V.A.
Partner: UNT Libraries Government Documents Department

A Synergistic Combination of Advanced Separation and Chemical Scale Inhibitor Technologies for Efficient Use of Imparied Water As Cooling Water in Coal-based Power Plants

Description: Nalco Company is partnering with Argonne National Laboratory (ANL) in this project to jointly develop advanced scale control technologies that will provide cost-effective solutions for coal-based power plants to operate recirculating cooling water systems at high cycles using impaired waters. The overall approach is to use combinations of novel membrane separations and scale inhibitor technologies that will work synergistically, with membrane separations reducing the scaling potential of the cooling water and scale inhibitors extending the safe operating range of the cooling water system. The project started on March 31, 2006 and ended in August 30, 2010. The project was a multiyear, multi-phase project with laboratory research and development as well as a small pilot-scale field demonstration. In Phase 1 (Technical Targets and Proof of Concept), the objectives were to establish quantitative technical targets and develop calcite and silica scale inhibitor chemistries for high stress conditions. Additional Phase I work included bench-scale testing to determine the feasibility of two membrane separation technologies (electrodialysis ED and electrode-ionization EDI) for scale minimization. In Phase 2 (Technology Development and Integration), the objectives were to develop additional novel scale inhibitor chemistries, develop selected separation processes, and optimize the integration of the technology components at the laboratory scale. Phase 3 (Technology Validation) validated the integrated system's performance with a pilot-scale demonstration. During Phase 1, Initial evaluations of impaired water characteristics focused on produced waters and reclaimed municipal wastewater effluents. Literature and new data were collected and evaluated. Characteristics of produced waters vary significantly from one site to another, whereas reclaimed municipal wastewater effluents have relatively more uniform characteristics. Assessment to date confirmed that calcite and silica/silicate are two common potential cycle-limiting minerals for using impaired waters. For produced waters, barium sulfate and calcium sulfate are two additional potential cycle-limiting minerals. For reclaimed municipal wastewater effluents, calcium ...
Date: August 30, 2010
Creator: Gill, Jasbir
Partner: UNT Libraries Government Documents Department


Description: Radiometric methods of analysis for magnesium and calcium have been developed as part of a program for the U. S. Atomic Energy Commission. Office of Isotopes Development, which are applicable to the determination of these elements in portland cement Both methods employ, as a precipitant, a standard solution of (NH/sub 4/)/sub 2/HPO/sub 4/ labeled with phosphorus-32. In the presence of NH/ sub 4/OH, this reagent precipitate; MgNH/sub 4/PO/sub 4/ or Ca/sub 3/(PO/sub 4/)/ sub 2/ from a solution of magnesium or calcium ions. The reduction in the radioactivity level of the labeled phosphate solution after precipitation serves as a measure of the phosphate reacted and thus a measure of the quantity of magnesium or calcium present. Studies have been made of the effects of reagent concentration, NH/sub 4/OH concentration, and other experimental variables. The interference of other elements present normally in portland cement and its raw materials has been determined. The concentration ranges for highest accuracy have been found to be 5 to 15 mg of MgO per 100 ml and 15 to 30 mg of CaO per 50 ml. (auth)
Date: February 18, 1960
Creator: Brown, C.T.; Howes, J.E. Jr.; Elleman, T.S.; Townley, C.W. & Sunderman, D.N.
Partner: UNT Libraries Government Documents Department

Biomimetic Nanocomposites of Calcium Phosphate and Self-Assembling Triblock and Pentablock Copolymers

Description: In an effort to mimic the growth of natural bone, self-assembling, micelle and gel-forming copolymers were used as a template for calcium phosphate precipitation. Because of the cationic characteristics imparted by PDEAEM end group additions to commercially available Pluronic{reg_sign} Fl27, a direct ionic attraction mechanism was utilized and a polymer-brushite nanocomposite spheres were produced. Brushite coated spherical micelles with diameters of {approx}40 nm, and agglomerates of these particles (on the order of 0.5 {mu}m) were obtained. Thickness and durability of the calcium phosphate coating, and the extent of agglomeration were studied. The coating has been shown to be robust enough to retain its integrity even below polymer critical micelle concentration and/or temperature. Calcium phosphate-polymer gel nanocomposites were also prepared. Gel samples appeared as a single phase network of agglomerated spherical micelles, and had a final calcium phosphate concentration of up to 15 wt%. Analysis with x-ray diffraction and NMR indicated a disordered brushite phase with the phosphate groups linking inorganic phase to the polymer.
Date: August 9, 2006
Creator: Enlow, Drew Lenzen
Partner: UNT Libraries Government Documents Department

Resorption Rate Tunable Bioceramic: Si, Zn-Modified Tricalcium Phosphate

Description: This dissertation is organized in an alternate format. Several manuscripts which have already been published or are to be submitted for publication have been included as separate chapters. Chapter 1 is a general introduction which describes the dissertation organization and introduces the human bone and ceramic materials as bone substitute. Chapter 2 is the background and literature review on dissolution behavior of calcium phosphate, and discussion of motivation for this research. Chapter 3 is a manuscript entitled ''Si,Zn-modified tricalcium phosphate: a phase composition and crystal structure study'', which was published in ''Key Engineering Materials'' [1]. Chapter 4 gives more crystal structure details by neutron powder diffraction, which identifies the position for Si and Zn substitution and explains the stabilization mechanism of the structure. A manuscript entitled ''Crystal structure analysis of Si, Zn-modified Tricalcium phosphate by Neutron Powder Diffraction'' will be submitted to Biomaterials [2]. Chapter 5 is a manuscript, entitled ''Dissolution behavior and cytotoxicity test of Si, Zn-modified tricalcium phosphate'', which is to be submitted to Biomaterials [3]. This paper discusses the additives effect on the dissolution behavior of TCP, and cytotoxicity test result is also included. Chapter 6 is the study of hydrolysis process of {alpha}-tricalcium phosphate in the simulated body fluid, and the phase development during drying process is discussed. A manuscript entitled ''Hydrolysis of {alpha}-tricalcium phosphate in simulated body fluid and phase transformation during drying process'' is to be submitted to Biomaterials [4]. Ozan Ugurlu is included as co-authors in these two papers due to his TEM contributions. Appendix A is the general introduction of the materials synthesis, crystal structure and preliminary dissolution result. A manuscript entitled ''Resorption rate tunable bioceramic: Si and Zn-modified tricalcium phosphate'' was published in Ceramic Engineering and Science Proceedings (the 29th International Conference on Advanced Ceramics and Composites - Advances in Bioceramics ...
Date: August 9, 2006
Creator: Wei, Xiang
Partner: UNT Libraries Government Documents Department

Preparation of pHEMA-CP composites with high interfacial adhesionvia template-driven mineralization

Description: We report a template-driven nucleation and mineral growth process for the high-affinity integration of calcium phosphate (CP) with a poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel scaffold. A mineralization technique was developed that exposes carboxylate groups on the surface of crosslinked pHEMA, promoting high-affinity nucleation and growth of calcium phosphate on the surface along with extensive calcification of the hydrogel interior. External factors such as the heating rate, the agitation of the mineral stock solution and the duration of the process that affect the outcome of the mineralization were investigated. This template-driven mineralization technique provides an efficient approach toward bonelike composites with high mineral-hydrogel interfacial adhesion strength.
Date: December 5, 2002
Creator: Song, Jie; Saiz, Eduardo & Bertozzi, Carolyn R.
Partner: UNT Libraries Government Documents Department

Chapter 9: Model Systems for Formation and Dissolution of Calcium Phosphate Minerals

Description: Calcium phosphates are the mineral component of bones and teeth. As such there is great interest in understanding the physical mechanisms that underlie their growth, dissolution, and phase stability. Control is often achieved at the cellular level by the manipulation of solution states and the use of crystal growth modulators such as peptides or other organic molecules. This chapter begins with a discussion of solution speciation in body fluids and relates this to important crystal growth parameters such as the supersaturation, pH, ionic strength and the ratio of calcium to phosphate activities. We then discuss the use of scanning probe microscopy as a tool to measure surface kinetics of mineral surfaces evolving in simplified solutions. The two primary themes that we will touch on are the use of microenvironments that temporally evolve the solution state to control growth and dissolution; and the use of various growth modifiers that interact with the solution species or with mineral surfaces to shift growth away from the lowest energy facetted forms. The study of synthetic minerals in simplified solution lays the foundation for understand mineralization process in more complex environments found in the body.
Date: July 29, 2006
Creator: Orme, C. A. & Giocondi, J. L.
Partner: UNT Libraries Government Documents Department

Chemical effects head-loss research in support of generic safety issue 191.

Description: This summary report describes studies conducted at Argonne National Laboratory on the potential for chemical effects on head loss across sump screens. Three different buffering solutions were used for these tests: trisodium phosphate (TSP), sodium hydroxide, and sodium tetraborate. These pH control agents used following a LOCA at a nuclear power plant show various degrees of interaction with the insulating materials Cal-Sil and NUKON. Results for Cal-Sil dissolution tests in TSP solutions, settling rate tests of calcium phosphate precipitates, and benchmark tests in chemically inactive environments are also presented. The dissolution tests were intended to identify important environmental variables governing both calcium dissolution and subsequent calcium phosphate formation over a range of simulated sump pool conditions. The results from the dissolution testing were used to inform both the head loss and settling test series. The objective of the head loss tests was to assess the head loss produced by debris beds created by Cal-Sil, fibrous debris, and calcium phosphate precipitates. The effects of both the relative arrival time of the precipitates and insulation debris and the calcium phosphate formation process were specifically evaluated. The debris loadings, test loop flow rates, and test temperature were chosen to be reasonably representative of those expected in plants with updated sump screen configurations, although the approach velocity of 0.1 ft/s used for most of the tests is 3-10 times that expected in plants with large screens . Other variables were selected with the intent to reasonably bound the head loss variability due to arrival time and calcium phosphate formation uncertainty. Settling tests were conducted to measure the settling rates of calcium phosphate precipitates (formed by adding dissolved Ca to boric acid and TSP solutions) in water columns having no bulk directional flow. For PWRs where NaOH and sodium tetraborate are used to control sump ...
Date: October 31, 2006
Creator: Park, J. H.; Kasza, K.; Fisher, B.; Oras, J.; Natesan, K.; Shack, W. J. et al.
Partner: UNT Libraries Government Documents Department

Studies with Colloids Containing Radioisotopes of Yttrium, Zirconium, Columbium and Lanthaum: 2. The Controlled Selective Localization of Radioisotopes of Yttrium, Zirconium, Columbium in the Bone Marrow, Liver and Spleen

Description: Several workers have shown that certain colloidally dispered materials are removed from the blood stream by the liver and spleen. Jones, Wrobel, and Lyons have utilized suspensions of anhydrous chromic phosphate for the selective irradiation of the liver and spleen with p{sup 32} beta particles. Gersh demonstrated that colloidal calcium phosphate is taken up by the liver and spleen. He stressed the failure of bone marrow phagocytes to take up this colloid in rats and dogs (though he referred to possible uptake in the marrow of rabbits under special conditions), and commented on the relative 'refractoriness' in general of the bono marrow as compared with liver and spleen with respect to the uptake of colloidal dyes from the blood stream. Some histological data indicate that 'Thorotrast' (a colloidal thorium dioxide preparation) is deposited in the bone marrow as well as in the liver and spleen, but no quantitative data as to the relative distribution are available. In the preceding communication the methods for the preparation of colloids incorporating radioisotopes of yttrium, columbium, and zirconium were given. The present studies are concerned with the localization of such colloids primarily in the bone marrow or primarily in the spleen and liver, with an analysis of some of the factors which may be responsible for differences in localization.
Date: April 21, 1948
Creator: Dobson, E.L.; Gofman, J.W.; Jones, H.B.; Kelly, Lola S. & Walker, L.
Partner: UNT Libraries Government Documents Department


Description: A new rapid separation method for radiostrontium in emergency milk samples was developed at the Savannah River Site (SRS) Environmental Bioassay Laboratory (Aiken, SC, USA) that will allow rapid separation and measurement of Sr-90 within 8 hours. The new method uses calcium phosphate precipitation, nitric acid dissolution of the precipitate to coagulate residual fat/proteins and a rapid strontium separation using Sr Resin (Eichrom Technologies, Darien, IL, USA) with vacuum-assisted flow rates. The method is much faster than previous method that use calcination or cation exchange pretreatment, has excellent chemical recovery, and effectively removes beta interferences. When a 100 ml sample aliquot is used, the method has a detection limit of 0.5 Bq/L, well below generic emergency action levels.
Date: July 17, 2008
Creator: Maxwell, S. & Culligan, B.
Partner: UNT Libraries Government Documents Department


Description: The Savannah River Site Environmental Bioassay Lab participated in the 2008 NRIP Emergency Response program administered by the National Institute for Standards and Technology (NIST) in May, 2008. A new rapid column separation method was used for analysis of actinides and {sup 90}Sr the NRIP 2008 emergency water and urine samples. Significant method improvements were applied to reduce analytical times. As a result, much faster analysis times were achieved, less than 3 hours for determination of {sup 90}Sr and 3-4 hours for actinides. This represents a 25%-33% improvement in analysis times from NRIP 2007 and a {approx}100% improvement compared to NRIP 2006 report times. Column flow rates were increased by a factor of two, with no significant adverse impact on the method performance. Larger sample aliquots, shorter count times, faster cerium fluoride microprecipitation and streamlined calcium phosphate precipitation were also employed. Based on initial feedback from NIST, the SRS Environmental Bioassay Lab had the most rapid analysis times for actinides and {sup 90}Sr analyses for NRIP 2008 emergency urine samples. High levels of potential matrix interferences may be present in emergency samples and rugged methods are essential. Extremely high levels of {sup 210}Po were found to have an adverse effect on the uranium results for the NRIP-08 urine samples, while uranium results for NRIP-08 water samples were not affected. This problem, which was not observed for NRIP-06 or NRIP-07 urine samples, was resolved by using an enhanced {sup 210}Po removal step, which will be described.
Date: August 27, 2008
Creator: Maxwell, S. & Culligan, B.
Partner: UNT Libraries Government Documents Department