bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long Term Durability Testing of Simulated Iron-Phosphate Nuclear Waste Glass
Authors: Haworth H. , Wronkiewicz D. J. , Day D. E. 
Published: April 2011

ABSTRACTAn iron phosphate base glass and a simulated Hanford Tank Farm B (TFB) waste loaded iron phosphate glass were reacted under both Product Consistency Test (PCT) and Vapor Hydration Test (VHT) conditions. Solution aliquots were collected following reaction of the TFB glass after the completion of a PCT at 90°C for time periods of 7, 49, 185, 274, and 365 days. Normalized element release patterns for sodium were highest of all the elements present, with values initially decreasing between 7 and 182 days and then increasing thereafter. Normalized release values for phosphorous declined between 49 and 182 days but increased thereafter, whereas calcium contents declined to and remained below the analytical detection limit after 182 days. Normalized element release patterns for Ce, Nd, and Fe were below 0.00045 g/m2 for all time periods tested. Amorphous iron oxide and elongate crystals (possibly apatite?) were noted as alteration products in both long-term PCT and short-term VHT formats.The VHT samples were reacted at 150°C for time periods of 3, 7, and 35 days for the base glass and 3, 7, 35, 91, 185, and 300 days using the TFB glass. Reacted samples were examined for alteration products, with an emphasis on identifying phases that could potentially occur during geologic disposal. The base glass reacted quickly under the VHT conditions. Phosphorous released from the base glass apparently formed phosphoric acid, which quickly lowered the solution pH to a value of one. The acidic nature of the fluids, in turn, led to an accelerated rate of glass corrosion. The addition of alkali and alkaline earth elements in the TFB glass prevented the low pH excursion seen in the base glass; possibly by ion exchange processes that remove hydrogen ions from solution, sequestering of phosphorous in alteration phases to prevent phosphoric acid formation, or both. This change led to a dramatic decrease in TFB glass reaction rates relative to the base glass composition. Alteration products included an amorphous iron precipitate and several crystalline phases.
Cathodoluminescence of Am3+ in zircon, (Zr,Pu,…)SiO4, and garnet, (Y,Gd,…)3(Al,Ga,…)5O12
Authors: Zamoryanskaya Maria V. , Hanchar John M. , Burakov Boris E. , Garbuzov Vladimir M. 
Published: April 2011

ABSTRACTCeramic waste forms based on garnet, (Y,Gd,An‥)3(Al,Ga,An‥)5O12, and zircon, (Zr,An‥)SiO4, where An=U, Pu, Np, Am, and Cm have been proposed for the immobilization of weapons-grade plutonium and other actinides. The lattice capacity of these materials depends on the valence state and ionic radius of the substitute ions. The method of cathodoluminescence (CL) allows the determination of the valence state of different ions (e.g., some transition metals, lanthanides, and actinides) in ceramic. There is a lack of information in the literature concerning CL properties of actinide ions. Cathodoluminescence images and emission spectra of synthetic yttrium-aluminum garnet, gallium-gadolinium garnet and zircon doped with Am were studied. Americium ion has three groups of lines of CL in visible region at 1.6eV, 1.9eV and 2.3eV. The interpretation of these lines has been done using the results of absorption spectra of Am in solution and in crystal LaCl3. There are f-f transitions of Am3+ ion. The ratio of intensities and the structure of these lines depend on the matrix. However, the spectral positions of these lines in two types of garnets and in zircon coincide. It was conclude that these lines can be used for identification of Am3+ ion in different crystalline matrices.
Impact of Atmospheric Pressure Fluctuations on Vadose-zone Contaminant Plumes
Authors: Downs Wayne C. 
Published: April 2011

ABSTRACTField and laboratory studies have been underway at the INEEL and BYU to investigate the effect of atmospheric pressure fluctuations on the migration of contaminant plumes.In the field, two vadose-zone piezometer nests were instrumented to measure soil-pressures and carbon tetrachloride concentrations at depths of roughly 78-ft, 112-ft., and 150-ft., below ground surface in wells 25-ft. apart. At land surface, a manifold was constructed to systematically rotate from port to port at 15-minute increments of time. Contaminant concentrations were measured at each rotation, and soil pressures were measured at all ports at 15-minute increments. Atmospheric pressures were also recorded. Results showed that atmospheric pressure changes propagated downward lagged in time and dampened in amplitude. Carbon tetrachloride concentrations were observed to decrease with pressure increases at each port, suggesting that pressure increases pushed the plume downward. Increases in concentration were observed with decreases in pressure. Concentrations were observed to change at a port by as much as an order of magnitude. Modeling is underway to assist in isolating the transport mechanisms involved and assist in quantifying the effect of varied pneumatic permeability on pressure propagation.Laboratory work is underway at BYU to more carefully isolate the mechanisms of diffusive transport and pressure fluctuation in unsaturated conditions. A sealed soil column has been packed with sand and instrumented with a contaminant reservoir at one end and concentration sensor at the other. A mechanical syringe is used to vary the pressure within the tube, and pressure sensors have been emplaced.An affiliation has been established with researchers at the DOE Sandia laboratory to utilize a novel non-invasive vapor detector in our sealed-column laboratory work.
Migration Behavior of Iron Ion in Compacted Bentonite Under Reducing Condition by using Electromigration.
Authors: Idemitsu Kazuya , Yano Seiji , Xia Xiaobin , Kikuchi Yoshiro , Inagaki Yaohiro , Arima Tatsumi 
Published: April 2011

ABSTRACTCarbon steel is one of the candidate overpack materials for high-level waste disposal and is expected to assure complete containment of vitrified waste glass during an initial period of 1000 years in Japan. The lifetime of the carbon steel overpack will depend on its corrosion rate. The corrosion rate of carbon steel is reduced by the presence of buffer material such as bentonite. Buffer material will delay the supply of corrosive materials and discharge of corrosion products through it. Carbon steel overpack will be corroded by consuming oxygen introduced by repository construction after closure of repository and then will keep the reducing environment in the vicinity of repository. The reducing condition will be expected to retard the migration of redox-sensitive radionuclides by lowering their solubilities. Therefore, the diffusion of corrosion products of iron in buffer material is important to discuss the corrosion rate of overpack, properties of buffer material and migration of redox-sensitive radionuclides. Electromigration experiments have been carried out with source of iron ions supplied by anode corrosion of iron coupon. Iron ions migrated as fast as 2mm in 2 or 3 hours under electrical field of 100V/m to the direction of cathode. Because the iron ions displaced exchangeable sodium ions in bentonite at a ratio of 1 to 2 during the electromigration, migrating iron ion could be ferrous ion.
Results of Vertical Scanning Interferometry (VSI) of Dissolved Borosilicate Glass: Evidence for Variable Surface Features and Global Surface Retreat
Authors: J.P. Icenhower , A. Lüttge , B.P. McGrail , M.S. Beig , R.S. Arvidson , E.A. Rodriguez , J.L. Steele , S.R. Baum 
Published: April 2011

ABSTRACTTwo disparate reaction mechanisms have been invoked to explain the reactivity of glass in contact with aqueous solution. One model is based on arguments from Transition State Theory (TST), which postulates that glass dissolution rates are surface reaction controlled. Alternatively, the second model argues that release of elements from glass to solution is governed by diffusion through an altered layer that forms on the surface of glass. Vertical Scanning Interferometry (VSI) is a new technique that allows one to observe surface features of specimens exposed to solution and may, potentially, be used to distinguish between competing models. We performed a series of dissolution experiments with a suite of glass compositions from chemically simple (sodium borosilicate) to complex (sixteen component borosilicate). Dissolution rates were determined using single-pass flow-through (SPFT) apparatus at 90°C and pH = 9 and over a solution saturation interval. Upon termination of the experiments, glass coupons were examined by VSI techniques. Effluent chemistry and VSI measurements indicate a nearly constant rate of 2.2 to 3.4 g m-2 d-1 over the solution interval; rates calculated from both methods are identical within experimental uncertainty. We argue that this glass is phase separated, and propose a model for dissolution based on the relative rates of dissolution of the two glass compositions. The data are consistent with a modified version of TST and indicate the potency of VSI methods to elucidate glass reaction mechanisms.
Fission Product Immobilisation in Secondary Phases Formed During Magnox Waste Glass Dissolution at 60 °C: Experimental Results and Modelling.
Authors: Abraitis Paul K. , Scales Charlie R. , Hyatt Neil C. 
Published: April 2011

ABSTRACTDissolution of a complex, simulated Magnox Waste (MW) glass in batch dissolution experiments at 60 °C over a period of 56 days is accompanied by extensive development of secondary gels. Gel development has been followed using a range of chemical, spectroscopic and physical means. Initially, a surface layer comprising (hydr)oxides of Fe, Zr and the lanthanides develops at the glass surface. Aluminosilicate gels containing Si, Al, Mg, Sr, Cs and Rb develop in systems where sufficient quantities of glass derived solutes accumulate in the leachate. These gels are hydrous and readily soluble in acidic oxalate solutions. Solution chemistry data is consistent with the development of Cs,Sr-bearing aluminosilicates, silica gel and (hydr)oxides of hydrolysis prone waste components. The experimental results are compared with the predictions of a model that considers kinetically constrained glass dissolution and the precipitation of secondary phases, including a Cs,Sr-bearing aluminosilicate gel.
The Effect of Radiation Damage on Zirconolite Dissolution
Authors: Smith Katherine L. , Zhang Zhaoming , McGlinn Peter , Attard Darren , Li Huijing , Lumpkin Gregory R. , Colella Michael , McLeod Terry , Aly Zaynab , Loi Elaine , Leung Sammy , Hart Kaye P. , Ridgway Mark , Weber William J. , Thevuthasan Suntharampillai 
Published: April 2011

ABSTRACTPolished tiles (7×7×2 mm3) of Nd-bearing zirconolite were fabricated and then some were irradiated on both large faces with 3 MeV or 2 MeV Au2+ ions (total fluence of ≥ 1 × 1015 ions/cm2) in order to render the zirconolite amorphous and so simulate displacement damage caused by alpha decay. Both the irradiated and non-irradiated tiles were then subjected to static dissolution tests in 0.01M nitric solution (pH2) at 90 C, for periods of 0–1, 1–7, 7–14 and 14–28 days. It was found that radiation damage did not affect the dissolution rate of zirconolite as indicated by the elemental leach rates of Nd, Ti, Ca and Al. The results of solution analyses are consistent with those obtained from X-ray Photoelectron Spectroscopy (XPS) in that the Ca, Nd, Ti and Al concentrations in the top surface layer (< 5 nm) all decreased with respect to that of Zr after dissolution testing, and the leached surface composition of the non-irradiated zirconolite is very similar to that of the two irradiated specimens. The implications of these results are discussed in the context of previous work.
Preparation and Characterization of a Calcium Phosphate Ceramic for the Immobilization of Chloride-containing Intermediate Level Waste
Authors: Metcalfe Brian L. , Donald Ian W. , Scheele Randy D. , Strachan Denis M. 
Published: April 2011

ABSTRACTAttention has recently been given to the immobilization of special categories of radioactive wastes, some of which contain high concentrations of actinide chlorides. Although vitrification in phosphate glass has been proposed, this was rejected because of the high losses of chloride through the mobilization of volatile species.On the basis of non-radioactive and, more recently, radioactive studies, we have shown that calcium phosphate is an effective host for immobilizing the chloride constituents [1]. In this instance, the chlorine is retained as chloride, rather than evolved as a chlorine-bearing gas. The immobilized product is in the form of a free-flowing, non-hygroscopic powder, in which the chlorides are chemically combined within the synthetic mineral phases chlorapatite [Ca5(PO4)3Cl] and spodiosite [Ca2(PO4)Cl]. Data from studies on non-radioactive simulated waste consisting of a mixture of CaCl2 and SmCl3, and radioactive simulated waste composed of CaCl2 with PuCl3 or PuCl3 and AmCl3, are presented and compared.The XRD data confirm the presence of chlorapatite and spodiosite in the non-radioactive and radioactive materials. The durability of all specimens was measured with a modified MCC-1 test. Normalized releases of Cl after 28 days were 1.6 × 10-3 g m-2 for the non-radioactive specimens and 7 × 10-3 g m-2 for the Pu bearing specimens. Releases of Ca after 28 days were 0.3 × 10-3 and 2.0 × 10-3 g m-2 for the non-radioactive composition and the Pu composition, respectively, whilst release of Pu from the radioactive specimens was higher for the mixed Pu/Am specimen at 1.2 × 10-5g m-2 than for the Pu only specimens. The release of Am from the mixed Pu/Am composition was exceptionally low at 2.4 × 10-7 g m-2. Overall, the release rate data suggest that the ceramics dissolve congruently, followed by precipitation of Sm, Pu and Am as less soluble phases, possibly oxides or phosphates. The differences in behaviour noted between non-radioactive and radioactive specimens are interpreted in terms of the crystal chemistry of the individual systems.
Xps and Sem Studies on the Corrosion of UO2Cointaining Plutonium in Demineralized and Carbonated Water.
Authors: Cobos J. , Wiss T. , Gouder T. , Rondinella V. V. 
Published: April 2011

ABSTRACTAn oxidation and dissolution study has been performed on UO2pellets containing ∼10 and ∼0.1 wt. %238Pu, ∼10 wt. %239Pu and on undoped UO2to investigate the effects of radiolysis and composition on the corrosion behavior of spent fuel. The so-called alpha-doped UO2is used to simulate the alpha-radiation field of different types of commercial LWR spent fuel after different storage times. Leaching experiments in demineralized and carbonated water at room temperature under oxidizing conditions showed that relatively high amounts of238Pu were released. The leached surfaces were examined with X-ray Photoemission Spectroscopy (XPS), and the progressive surface oxidation was monitored. The oxidation of the U(IV) during the leaching experiments, in the materials doped with238Pu resulted in precipitation of U(VI) phases: enhanced formation of studtite for the strongest radiation field and shoepite at low radiation field was observed on the surface of the pellet. Essentially no precipitation of Pu-rich phases was directly observed. Leaching in carbonated water and characterization of UO2containing239Pu under the same experimental conditions were performed and the results compared to those for alpha-doped UO2. The chemistry effects due to the presence of Pu in addition to alpha-radiolysis were investigated.
Bone Tissue Scaffold Technologies Based on RP Adopted Droplet Assembly
Authors: Zhang Renji , Yan Yongnian , Lin Feng 
Published: April 2011

ABSTRACTTissue engineering tries to grow replacement tissues to repair damaged bones. In this paper, the fabrication technology of Multi-nozzle Deposition Manufacturing (MDM) was adopted to fabricate scaffolds of a tissue engineered bone at low temperature. The composite of poly(L-lactic acid) and tri-calcium phosphate (TCP) was chosen to form bone tissue engineering scaffolds. The new computer aided manufacturing process can make porous PLLA/TCP scaffolds. A new surface processing technology of apatite coating on bone tissue engineered scaffolds was also adopted. This digital forming technology was based on rapid prototyping (RP), in which a digital droplets assembly technology was introduced. The MDM technology of 4 nozzles was developed based on the layer-by-layer manufacturing principle of Solid Freeform Fabrication (SFF) in our laboratory. The bone scaffolds made by the multi-nozzle deposition process in the MDM system have good biocompatibility and bone conductive properties as a molecular scaffold for bone morphogenic protein (BMP) in the implantation experiment of repairing segment defects in rabbits' and dogs' radiuses.
A Process to Make Collagen Scaffolds with an Artificial Circulatory System using Rapid Prototyping
Authors: Sachlos Eleftherios , Reis Nuno , Ainsley Chris , Derby Brian , Czernuszka Jan T. 
Published: April 2011

ABSTRACTTissue engineering aims to produce biological substitutes to restore or repair damaged human tissues or organs. The principle strategy behind tissue engineering involves seeding relevant cell(s) onto porous 3D biodegradable scaffolds. The scaffold acts as a temporary substrate where the cells can attach and then proliferate and differentiate. Collagen is the major protein constituent of the extracellular matrix in the human body and therefore an attractive scaffold material. Current collagen scaffolds are foams which limit the mass transport of oxygen and nutrients deep into the scaffold, and consequently cannot support the growth of thick-cross sections of tissue (greater than 500 μm). We have developed a novel process to make collagen and collagen-hydroxyapatite scaffolds containing an internal artificial circulatory system in the form of branching channels using a sacrificial mould, casting and critical point drying technique. The mould is made using a commercial rapid prototyping system, the Model-Maker II, and is designed to possess a series of connected shafts. The mould is dissolved away and the solvent itself removed by critical point drying with liquid carbon dioxide. Processed hydroxyapatite has been characterised by XRD and FTIR analysis. Tissue engineering with collagen scaffolds possessing controlled internal microarchitecture may be the key to growing thick cross-sections of human tissue.
Effect of White and Red Light Illumination on the Degradation of a-Si:H Solar Cells
Authors: Jamali-Beh Taraneh , Chen I.-S , Liu H. , Lee Y. , Wronski C. R. 
Published: April 2011

ABSTRACTStructures were carried out on the degradation of heterojunction and homojunction a-Si:H solar cells, using Xenon arc and tungsten halogen light sources. The degradations were carried out with both white and red light with the intensities being calibrated using the saturated reverse biased photocurrents. Because of the different light intensities, I, involved, comparisons between the different illumination were made after exposure times, t, where I1.8t = constant. The degraded states of the cells were characterized with light I-V, dark I-V, and quantum efficiency measurements. The same degraded states, as indicated by the all three characteristics, are obtained with either white and red light providing the intensities are calibrated using the actual p-i-n cells. It is also found that the empirical relation for obtaining the same degradation found by L. Yang holds for these illuminations being about 1 and 10 suns. Analysis of the dark I-V's using AMPS with a charged defect distributions of defects indicates that with the exposures used, the light induced defects have a close to uniform distribution throughout the i-layer.
Characterization of 0.5 MHz Silicon-Based Ultrasonic Nozzles Using Multiple Fourier Horns
Authors: Tsai Shirley C. , Song Yu L. , Chou Yuan F. , Tseng Terry K. , Chen W. J. , Yang J. H. , Chen J. W. , Tsai Chen S. 
Published: April 2011

ABSTARCTThis paper presents the experimental results of impedance analysis and longitudinal vibration measurement of micro-fabricated 0.5 MHz silicon-based ultrasonic nozzles. Each nozzle is made of a piezoelectric drive section and a silicon-resonator consisting of multiple Fourier horns each with half wavelength design and twice amplitude magnification. The experimental results verified the simulation prediction of one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude gain at the nozzle tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical value of 2n. Using this design, very high vibration amplitude at the nozzle tip can be achieved with no reduction in the tip cross sectional area. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.
A Scheme of Micromanipulation using a Liquid Bridge
Authors: Obata Kenichi J. , Saito Shigeki , Takahashi Kunio 
Published: April 2011

ABSTRACTThis paper presents a scheme of micromanipulation with a liquid bridge and an analysis of the capillary forces involved. The following procedure is considered in this article: (a) PICK UP: a probe, with liquid in the tip, approaches the target object. (b) A liquid bridge forms between the object and the tip of the probe. (c) The object is picked up by means of the capillary force of the liquid bridge. (d) TRANSPORT: The probe ascends, moves to the target point, and descends towards a substrate. (e) PLACEMENT: At a given height, a second liquid bridge made from a drop previously applied at the target point on the substrate, forms between the object and the substrate. (f) The probe ascends and the probe-object bridge collapses.The collapse can be predicted through the stability analysis of the bridge and its condition can be controlled by the regulation of the liquid volume. The liquid volumes required for the manipulation, in the first and second liquid bridge, are calculated in this paper.
Layer-by-Layer Engineered Microreactors for Bio-Polymerization of 4-(2-aminoethyl) phenol hydrochloride
Authors: Ghan R. , Shutava T. , Patel A. , John V. , Lvov Y. 
Published: April 2011

ABSTRACTThis study presents the results of polymerization of phenol to yield fluorescent polymer encapsulated within shells fabricated via layer-by-layer (L-b-L) assembly. Hollow polyelectrolyte microcapsules (shells) were prepared using weakly cross-linked melamine formaldehyde (MF) particles. Dissolution of the MF cores was achieved by changing the pH of the solution. Horseradish peroxidase (HRP), the catalyzing enzyme, was loaded in these capsules by taking advantage of the “open/close” mechanism of the capsules by altering the pH. The empty shells were then suspended in a concentrated solution of monomer. Since the monomer is a low molecular weight species, it freely permeates through the polyion wall into the shells. Addition of aliquots of hydrogen peroxide initiated the polymerization reaction and the polymer formed from the ensuing reaction was confined in the shells due to its high molecular weight. The model used for demonstrating this synthesis is polymerization of 4-(2-aminoethyl) phenol hydrochloride commonly known as tyramine hydrochloride to its corresponding polymeric form by reacting it with hydrogen peroxide. Fluorescence spectrometry (FS), confocal laser scanning microscopy (CLSM), and atomic force microscopy (AFM) were the characterization methods employed to confirm polymerization in situ shells.