bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linear and cross-linked mixed conducting polycarbazoles for electrochromic devices
Authors: Tran-Van François , Vancaeyzeele Cédric , Henri Thierry , Grazulevicius Juozas V. , Chevrot Claude 
Published: April 2011

ABSTRACTA carbazole N-substituted by an oxyethylene group was polymerized using oxidative electro-polymerization. Due to the hydrophilic properties of the oligooxyethylene substituent, this monomer can be electropolymerized in aqueous solution. An acidic medium is particularly appropriate in order to decrease the oxidation potential of the monomer and to obtain films mainly composed of oligomers as revealed by SEC analysis. More particularly interesting is the stability of such material during polarization. In acidic medium 1.25 mol.L-1 HClO4, 95% of the charge density was maintained after polarization for 7000 cycles which shows the good electrochemical stability of this material compared to other polycarbazoles. Moreover, films are electroactive in aqueous electrolytes and would be well-compatible with polyethylene-oxide solid electrolytes.In order to increase the mechanical properties of the film, we have also electropolymerized an oligomer with pendant carbazole groups obtained by acid catalyzed cationic ring opening polymerization of [N(2,3-epoxypropyl)carbazole] which leads to a new dicarbazyl cross-linked polymer with cations solvating oxyethylene segments. Due to their tridimensional structure, the mechanical strength of these films is superior to that of a linear polycarbazole film. However, their electroactivity in aqueous electrolyte is poor. So, the electropolymerization of a mixture of both monomers ensures good mechanical properties and compatibility with hydrophilic electrolyte in view to prepare an electrochromic device.
Materials Research in Nuclear Waste Management: Reflections on Twenty-Five MRS Symposia
Authors: Ewing Rodney C. 
Published: April 2011

ABSTRACTThe MRS symposium, “Scientific Basis for Nuclear Waste Management” was first held in Boston, November 28th to December 1st, 1978. This symposium marks the twenty-fifth in a series that now rotate to meeting sites around the world. During the past 24 years, there has been considerable progress in the development and understanding of the behavior of materials that are used in the processing, transport, containment and disposal of radioactive waste. The design and selection of materials for long-term performance has required a uniquely interdisciplinary effort. Over the same period, there have been important developments in the regulatory framework that guides the scientific and engineering needs of nuclear waste management. This paper provides a subjective commentary on the major developments and innovations during the past 25 symposia. The future challenge will be the proper and constructive integration of the science into the development of nuclear waste disposal strategies.
Instability model of the NaZr2(PO4)3 Structure
Authors: Troole Albert , Stefanovsky Sergey 
Published: April 2011

ABSTRACTIncorporation of paramagnetic species in NaZr2(PO4)3 (NZP) single crystal made possible to investigate local distortion of the NZP structure from EPR data. Cr3+ and Fe3+ ions were used as paramagnetic probes. We mapped invariant sum of cubic component of the fourth rank tensor of crystal field, the indicative surface of the B04 element of this tensor as well as 2nd, 3rd, and 4th orders axles of the cubic component of the same tensor. From these data the coordination polyhedron of the ion-probe has been modeled and direction to charge compensator has been determined. Based on the coordination polyhedron model obtained it has been shown how would the local symmetry be lowered from C3 (initial symmetry of the Zr-polyhedron) to C1 (Zr substitute ion-probe). A comparison of dynamics of the structure occurring at lowering the symmetry with allowed dynamics of the NZP structure (Roy -Alamo-Agrawal model) makes easily explainable why the dynamics observed results in an instability of the NZP structure and breaking the symmetry from R 3c to C2/c.
A Cathodoluminescence Investigation of Pyrochlore, (Ca,Gd,Hf,U,Pu)2Ti2O7, Doped with 238Pu and 239Pu
Authors: Zamoryanskaya Maria V. , Burakov Boris E. , Bogdanov Roman V. , Sergeev Andrey S. 
Published: April 2011

ABSTRACTCrystalline ceramic based on the pyrochlore structure [(Ca,Gd,Hf,U,Pu)2Ti2O7], has been proposed in the U.S. as a candidate waste form for the immobilization of weapons grade plutonium. Several samples of synthetic polycrystalline pyrochlore doped separately with 238Pu and 239Pu were studied using cathodoluminescence (CL) and electron probe microanalysis (EPMA) immediately after synthesis and then after 175, 245 and 405 days. The CL spectra of pyrochlore doped with 239Pu and 238Pu obtained immediately after ceramic synthesis and 175 days later were nearly the same and characterized by a typical broad band emission with a maximum peak centered at 2.5 eV. New CL peaks with maximum intensities at 2.0 and 2.3 eV in the emission spectra of 238Pu-and 239Pu-doped pyrochlore were observed 245 days later. It was determined that this newly formed CL peak at 2.3 eV is similar to one in CL spectrum of artificial standard glass doped with the uranyl ion, (UO2)2+. It was suggested that CL band with maximum at 2.0 eV is caused by the U tetrahedral complex (UO4)2-. Also, the same peaks were observed in the CL spectrum of natural U-rich pyrochlore containing approximately 23 wt.% U (mainly in the form of uranyl ion). The results obtained allow us to conclude that the radiation damage of pyrochlore-based ceramic waste form is accompanied with conversion of tetravalent uranium incorporated into pyrochlore structure to the mobile uranyl ion, (UO2)2+, and complex (UO4)2-.
Experimental Determination of the Dissolution Kinetics of Plutonium- and Uranium-Bearing Ceramics at 90°C
Authors: Icenhower J. P. , McGrail B. P. , Strachan D. M. , Scheele R. D. , Legore V. L. , Rodriguez E. A. , Steele J. L. , Brown C. F. , O'Hara M. J. 
Published: April 2011

ABSTRACTAs a first step toward understanding the effects of radiation damage on element release rates from Ti-bearing waste forms, we performed single-pass flow-through (SPFT) experiments with 239Pu- and 238U-bearing ceramics over a solution pH-interval of 2 to 10 at 90°C. The ceramics tested are chemically complex and are dominated volumetrically by betafite (Ti-pyrochlore) (ABTi2O7) (A = Ca2+, Gd3+, B = Gd3+, Hf4+, Pu4+, U4/6+). The 239Pu-bearing specimens contained 11.9 mass% PuO2 and 23.7 mass% UO2. In addition, a 238Pu-bearing (11.8 and 23.9 mass% PuO2 and UO2, respectively) specimen was tested at pH = 2, 90°C. The 239Pu-bearing specimens slowly released Pu to solution (rate = 7.6x10-6 g m-2 d-1), even at pH = 2. Release of elements across the pH interval investigated exhibits a weak amphoteric behavior. Compared to results from the 239Pu-bearing materials, the 238Pu-bearing specimen released Pu >1000X faster (rate = 9.3x10-3 g m-2 d-1) at pH = 2. Release rates of U, Gd, and Hf are also faster from the 238Pu-bearing ceramic compared to the specimen containing 239Pu. Although preliminary, the data can be interpreted to indicate that accumulation of radiation damage may result in faster release of Pu and U to solution than previously suspected.
Thermotransport of Hydrogen in the Modified Zircaloy-4 as a Function of Hydrogen and Oxygen Concentrations
Authors: Kim Hyun Sook , Lee Kyung Sub , Kim Seon Jin 
Published: April 2011

ABSTRACTThe hydrogen redistribution induced by the thermotransport in the modified Zircaloy-4 at temperatures likely to be encountered in nuclear power reactors (300-340°C) was investigated by means of steady state techniques. The modified Zircaloy-4 was prepared by changing the chemical compositions of Zircaloy-4, which is used widely as a nuclear fuel cladding material in pressurized water reactors. The change of Q for hydrogen, which describes the direction and magnitude of the thermotransport, with increasing hydrogen and oxygen concentrations was investigated in the modified Zircaloy-4. The value of Q for hydrogen in the modified Zircloy-4 alloys was found to be about 7 kcal/mol and it was not affected by hydrogen concentration in the hydrogen concentration range from 63.3 ppm to 91.7 ppm. While the value of Q for hydrogen decreased from 6.8 kcal/mol to 4.5 kcal/mol with increasing oxygen concentration from 0.2 wt% to 1.0 wt% and it was considered to be due to the trapping of hydrogen by oxygen. In addition, the hydrogen redistribution and Q in Zircaloy-4 was also investigated in order to compare the characteristics of thermotransport of hydrogen between Zircaloy-4 and modified Zircaloy-4. The hydrogen redistribution and Q in Zircaloy-4 showed the same results to those of the modified Zircaloy-4.
Corrosion Testing of a Simulated Five-Metal Epsilon Particle in Spent Nuclear Fuel
Authors: Wronkiewicz D.J. , Watkins C.S. , Baughman A.C. , Miller F.S. , Wolf S.F. 
Published: April 2011

ABSTRACTThe five-metal epsilon particle represents an important component with respect to the corrosion of spent nuclear fuel as it is the principal host for 99Tc. This radionuclide has a high solubility in oxidizing environments (as TcO4 -), a half-life of 213,000 years, and has been proposed as a monitor for the corrosion rate of spent fuel. As such, an understanding of the corrosion processes affecting epsilon particles may have important implications on our ability to accurately assess radionuclide release rates from spent nuclear fuel.Non-radioactive metal powders were mixed in an atomic percent ratio of 40% Mo, 30% Ru, 15% Pd, 10% Re, and 5% Rh (Re used as a surrogate for Tc), a composition that simulates epsilon particles in spent reactor fuel [1,2]. The powders were electric arc-melted in the presence of an Ar-purged atmosphere. Scanning electron microscopy images of the as-cast samples denote a primary sample heterogeneity, with two distinct zones, each composed of a mixture of very fine-grained Mo-, Mo-Ru-Re, and Mo-Ru-Pd rich crystals. Results from vapor hydration tests (200°C) for time periods up to 35 days indicate the formation of Mo- and Reenriched alteration phases. Phase growth was enhanced when air was periodically replenished in the test vessels suggesting that oxide and/or hydroxide alteration phases may play a role in the corrosion process. MCC-1 tests (90°C) were conducted for time periods up to 182 days in leachant solutions that were prepared with either a) deionized water or b) deionized water acidified with nitric acid to a pH of 3.0. Solutions from the deionized water tests progressively decreased in pH with increasing reaction time (5.5 to 4.0), while the pH values remained at a near-constant value of 3.0 in the acidified solutions. Solution results indicate a preferential release of Mo followed by Re. Normalized Re/Mo release ratios varied from 0.20 to 0.86, and increased as a function of reaction time and acidity. Release of the platinum group metals (Pd, Rh, and Ru) was relatively insignificant in comparison to Mo and Re.
The Influence of Near Field Redox Conditions on Spent Fuel Leaching
Authors: Spahiu Kastriot , Eklund Ulla-Britt , Cui Daqing , Lundström Max 
Published: April 2011

ABSTRACTIn a repository, the spent fuel could come in contact with groundwater if the canister or container has breached. The system may be quite complex with oxygen-free water, uranium dioxide, a corroding metal, such as iron, and a radiation field present at the same time. In an anaerobic environment iron and mild steel will corrode and hydrogen will be evolved. The equilibrium hydrogen pressure for this reaction is very high. At some time after water intrusion, there will be large amounts of dissolved hydrogen in the near field, corresponding to a partial pressure at least equivalent to the hydrostatic pressure at the repository depth. For this reason, we investigated the leaching behavior of 0.25-0.5 mm sized fragments of PWR spent fuel (43 MWd / Kg U) in simulated groundwater solution (10 mM NaCl and 2 mM HCO3-) under 5 MPa hydrogen and argon pressure. In a leaching experiment under 5 MPa hydrogen at 25 °C, the total U concentration was found to be <10−8M. After refilling of the autoclave with new solution at 70°C, the total U concentration first increased to 10−6.3M, and then quickly decreased to 10−8M. The leaching behavior of uranium and other fuel components indicates that under pressurized hydrogen, the spent fuel dissolution is substantially hindered. Leaching results obtained after the substitution of hydrogen by argon at the same pressure and temperature are also presented. Finally, some results on spent fuel leaching under pressurized argon are presented and comparatively discussed.
Ion-Induced Amorphization of Murataite
Authors: Lian Jie , Yudintsev Sergey V. , Stefanovsky Sergey V. , Kirjanova Olga I. , Ewing Rodney C. 
Published: April 2011

ABSTRACTMurataite A4B2C7O22-x, where A = Na+, Ca2+, REE3+, An3+/4+; B = Mn2+/3+, Zn2+; C = Ti4+, Fe3+, Al3+; 0≤x≤1, is an isometric, derivative of the fluorite-structure. Murataite is potentially suitable as a phase for the immobilization of rare earth (REE) and actinide elements (An). Murataite structures with three-(3C), five-(5C), and eight-fold (8C) multiples of the fluorite unit cell parameters have been identified. Radiation-induced amorphization of murataite has been investigated by 1 MeV Kr+ ion irradiation of three ceramic samples produced by melting in a resistive furnace and a cold crucible at 1400-1600 °C. The 1 MeV Kr+ ion irradiations were performed at room temperature using IVEM-Tandem Facility at Argonne National Laboratory. Radiation damage was observed by in-situ TEM. Initially, the irradiation caused disordering of the murataite structure. Murataite was rendered fully amorphous at a dose of (1.7∼1.9)Á1018 ion/m2. The pyrochlore structure phase (2C) is more radiation resistant to ion irradiation-induced amorphization than the murataite structure. Combining results on murataite with those pyrochlore and fluorite, a generally increasing trend in the susceptibility to ion beam damage is found in the fluorite-related structures as a function of the increasing multiples of the fluorite unit cells.
Total-System Performance Assessment for the Yucca Mountain Site
Authors: Wilson Michael L. , Swift Peter N. , McNeish Jerry A. , Sevougian S. David 
Published: April 2011

ABSTRACTYucca Mountain, Nevada, is under consideration as a potential site for a repository for high-level radioactive waste. Total-system performance-assessment simulations are performed to evaluate the safety of the site. Features, events, and processes have been systematically evaluated to determine which ones are significant to the safety assessment. Computer models of the disposal system have been developed within a probabilistic framework, including both engineered and natural components. Selected results are presented for three different total-system simulations, and the behavior of the disposal system is discussed. The results show that risk is dominated by igneous activity at early times, because the robust waste-package design prevents significant nominal (non-disruptive) releases for tens of thousands of years or longer. The uncertainty in the nominal performance is dominated by uncertainties related to waste-package corrosion at early times and by uncertainties in the natural system, most significantly infiltration, at late times.
Dissolution of A2Ti2O7 (A = Y3+, Gd3+, or Lu3+) Pyrochlore by Experiment at pH = 2, T = 90°C: Evidence for Solubility Control Using a Linear Free Energy Model
Authors: Icenhower J. P. , McGrail B. P. , Weber W. J. , Begg B. D. , Hess N. J. , Rodriguez E. A. , Steele J. L. , Brown C. F. , O'Hara and M. J. 
Published: April 2011

ABSTRACTWe performed a series of dissolution experiments with well-characterized pyrochlore ceramics with the formula A2Ti2O7, where A = Y3+, Gd3+, or Lu3+ in H2O- and D2Obased solutions [pH(D) = 2] at 90°C. Normalized log10 dissolution rates (g·m−2·d−1) in H2O-based solutions increase from Lu2Ti2O7 (−3.2 to –3.3) to Gd2Ti2O7 (−2.6 to –2.9), to Y2Ti2O7 (−1.9 to –2.0). Rates in D20-based solutions are indistinguishable from rates in H2O, indicating that release of elements is probably not diffusion controlled. A recent dissolution model, based on ligand-exchange reactions, suggests that the rate of reaction should increase in inverse order of the cation field strength: Lu < Y < Gd (where the cation denotes the appropriate pyrochlore composition), which is not observed. Evaluation of the thermodynamic stability of the three solids was performed using a linear free-energy model and reported free energies of formation. The calculations indicate that reactivity should follow in the progression Lu < Gd < Y, as observed in the dissolution experiments. Our data indicates, therefore, that dissolution models based on ligand-exchange reactions may not be strictly applicable to simple pyrochlore minerals.
Development of the Post-Closure Safety Case for the Low Level Waste Disposal Site at Drigg, United Kingdom
Authors: Watts Len 
Published: April 2011

ABSTRACTThis paper provides an overview of the development of the post-closure safety case (PCSC) for the solid low level radioactive waste (LLW) disposal site at Drigg. The paper outlines the background to the site, the implementation of a systematic approach to understanding the site and undertaking a post-closure radiological safety assessment (PCRSA), communication activities, key factors in the PCSC and issues to be investigated further in the forward programme.The Drigg site is the UK's principal near-surface facility for disposal of LLW. Disposals commenced in 1959 to trenches whereas current practice involves disposal to concrete vaults. Disposals are carried out under an authorisation from the UK Environment Agency. Periodically the Environment Agency reviews the authorisation to ensure consistency with current regulatory requirements. British Nuclear Fuels plc (BNFL) will produce an updated PCSC in 2002; in preparation for this, BNFL published in March 2000 a status report on the development of the PCSC.BNFL and the Environment Agency conduct an information exchange process on the development of the PCSC. This process has led to notable improvements, as well as affording a mechanism for providing clarifications and building confidence in the PCSC. BNFL undertakes other communication activities including scientific publication, conference presentation, participation in international programmes (such as those of the IAEA and NEA) and liaison with local communities. Peer review of the PCSC is also being carried out.Central to the safety case is a systematic PCRSA, which promotes transparency and traceability and demonstrates a rigorous treatment of relevant uncertainties. The approach aligns with international best practice for near-surface disposal facilities and includes the assessment of features, events and processes and the use of tools such as conceptual model uncertainty forms. This formalisation helps to identify and understand the key factors for the PCSC. Additional qualitative or simple quantitative information is used to augment the PCRSA so as to provide a wider context to inform decision-making.
Magnetic Recording at High Densities on Protein-Derived CoPt Nanoparticles
Authors: Hoinville Jay , Bewick Angus , Gleeson David , Jones Richard , Kasyutich Oksana , Mayes Eric , Nartowski Artur , Warne Barnaby , Wiggins Jason , Wong Kim 
Published: April 2011

ABSTRACTThis paper reports on the progress in developing self organized nanoparticulate arrays for magnetic recording at densities beyond 30 Gbit/cm2 (200 Gbit/in2), and in particular describes the beneficial use of biological templates in developing such arrays. Chemically synthesized, high magnetocrystalline anisotropy magnetic nanoparticles have demonstrated extremely narrow size distributions that are critical in reducing media noise. Due to their monodispersity, they also exhibit emergent self-patterning that could potentially support bit-per-particle densities up to 2–8 Tbit/cm2 (10–50 Tbit/in2).High anisotropy L10 CoPt precursor grains are prepared within apoferritin from aqueous reactants, with synthesis conditions controlling grain size, structure and composition. Smooth films on glass disk substrates are produced by either spin- or dip-coating from aqueous dispersions of the precursor material. Films are typically annealed at 590 °C for 60 minutes with a 19 kPa (190 mBar) partial pressure of H2 to form the L10 phase.We report on recently produced films that have demonstrated moderate-density recording using a contact drag tester with commercial, 0.35 μm-wide magnetoresistive (MR) heads. The highest areal density currently achieved for these nanoparticulate films is 0.93 Gbit/cm2 (6.0 Gbit/in2).
Nano-fibrous scaffolding architecture enhances protein adsorption and cell attachment
Authors: Woo Kyung Mi , Chen Victor J. , Ma Peter X. 
Published: April 2011

ABSTRACTTissue engineering aims at resolving problems such as donor shortage and immune rejection faced in transplantation. Scaffolds (artificial extracellular matrices) play critical roles in tissue engineering. Recently, we developed nano-fibrous poly(L-lactic acid) (PLLA) scaffolds under the hypothesis that synthetic nano-fibrous scaffolding, mimicking the structure of natural collagen fibers, could create a more favorable microenvironment for cells. This is the first report that the nano-fibrous architecture built in three-dimensional scaffolds improved the features of protein adsorption, which mediates cell interactions with scaffolds. Scaffolds with nano-fibrous pore walls adsorbed 4 times more serum proteins than scaffolds with solid pore walls. More interestingly, the nano-fibrous architecture selectively enhanced protein adsorption including fibronectin and vitronectin, even though both scaffolds were made from the same PLLA material. Furthermore, nano-fibrous scaffolds also allowed more than 1.7 times of osteoblastic cell attachment than scaffolds with “solid” pore walls. These results demonstrate that the biomimetic nano-fibrous architecture serves as superior scaffolding for tissue engineering.
Washing of Electrotextiles
Authors: Slade Jeremiah , Agpaoa-Kraus Marty , Bowman Jeremy , Riecker Andrew , Tiano Tom , Carey Charles , Wilson Patricia 
Published: April 2011

ABSTRACTThe ability to integrate electrical functionality into textile garments is becoming increasingly desired for consumer devices, military applications and for companies with large distributed workforces. This technology has the potential to facilitate the transfer of information and increase efficiency in many arenas. One of the major hurdles that has hindered the wedding of electronics and clothing has been the need to wash the resulting garment. This paper describes a study of the long term effects of washing and dry-cleaning electrotextile elements.