[en] High-Resolution Mineralogical Characterization and Biogeochemical Modeling of Uranium Reduction Pathways at the Oak Ridge Field-Research Center (FRC) Chen Zhu, Indiana University, David R. Veblen, Johns Hopkins University We have successfully completed a proof-of-concept, one-year grant on a three-year proposal from the former NABIR program, and here we seek additional two-year funding to complete and publish the research. Using a state-of-the-art 300-kV, atomic resolution, Field Emission Gun Transmission Electron Microscope (TEM), we have successfully identified three categories of mineral hosts for uranium in contaminated soils: (1) iron oxides; (2) mixed manganese-iron oxides; and (3) uranium phosphates. Method development using parallel electron energy loss spectroscopy (EELS) associated with the TEM shows great promise for characterizing the valence states of immobilized U during bioremediation. We have also collected 27 groundwater samples from two push-pull field biostimulation tests, which form two time series from zero to approximately 600 hours. The temporal evolution in major cations, anions, trace elements, and the stable isotopes 34S, 18O in sulfate, 15N in nitrate, and 13C in dissolved inorganic carbon (DIC) clearly show that biostimulation resulted in reduction of nitrate, Mn(IV), Fe(III), U(VI), sulfate, and Tc(VII), and these reduction reactions were intimately coupled with a complex network of inorganic reactions evident from alkalinity, pH, Na, K, Mg, and Ca concentrations. From these temporal trends, apparent zero order rates were regressed. However, our extensive suite of chemical and isotopic data sets, perhaps the first and only comprehensive data set available at the FRC, show that the derived rates from these field biostimulation experiments are composite and lump-sum rates. There were several reactions that were occurring at the same time but were masked by these pseudo-zero order rates. A reaction-path model comprising a total of nine redox couples (NO3?/NH4+, MnO2(s)/Mn2+, Fe(OH)3(s)/Fe2+, TcO4?/TcO2(s), UO22+/UO2(s), SO42?/HS?, CO2/CH4, ethanol/acetate, and H+/H2.) is used to simulate the temporal biogeochemical evolution observed in the field tests. Preliminary results show that the models based on thermodynamics and more complex rate laws can generate the apparent zero order rates when several concurrent or competing reactions occur. Professor Alex Halliday of Oxford University, UK, and his postdoctoral associates are measuring the uranium isotopes in our groundwater samples. Newly developed state-of-the-art analytical techniques in measuring variability in 235U/238U offer the potential to distinguish biotic and abiotic uranium reductive mechanisms

[en] Both Landau instability and dynamical instability of Bose-Einstein condensates in moving two-dimensional optical lattices are investigated numerically and analytically. Phase diagrams for both instabilities are obtained numerically for different system parameters. These phase diagrams show that the Landau instability does not depend on direction for weak lattices while the dynamic instability is direction dependent. These features are explained analytically.

[en] In the recent years, a number of methods had been reported for preparing tin disulfide (SnS_2) films. Compared with the other available methods, close-spaced sublimation (CSS) was reported as a simple, cost-effective, and non-wet thin film deposition technique. The present research aimed to demonstrate a CSS approach to prepare SnS_2 thin films using SnS_2 powder as a source. The influence of the source temperature on the chemical composition, crystal structure, surface morphology, and optical band gap of tin sulfide thin films was systemically investigated by energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscope, and ultraviolet–visible absorption spectra, respectively. By the CSS technique, SnS_2 thin films were prepared at the source temperature of 580 °C, and SnS_2 crystals showed a characteristic of a preferred orientation along (001) plane, possessing hexagonal phase and sheet appearance. The optical band gap of SnS_2 thin films was calculated to be 2.08 eV. At the source temperature of 650 °C, the tin sulfide thin films mainly consisted of Sn_2S_3 along with other phases and exhibited rod appearance. Therefore, it was found that the optimal source temperature for the preparation of SnS_2 thin films was 580 °C using the CSS method. Further studies are recommended to optimize and apply this thin film in solar cells. - Highlights: ► Preparation of SnS_2 thin film by close-spaced sublimation using SnS_2 powder ► The source temperature was a key factor in the preparation of SnS_2 thin films. ► The source temperature 580 °C is suitable for the preparation of SnS_2 thin film

[en] Several major issues on emergency planning and preparation in nuclear facilities were discussed -- such as the importance of emergency planning and preparation, basic principles of intervention and implementation of emergency plan and emergency training and drills to insure the effectiveness of the emergency plan. It is emphasized that the major key point of emergency planning and response is to avoid the occurrence of serious nonrandom effect. 12 refs., 3 tabs

[en] The effectiveness and feasibility of bioremediation at the field scale cannot be fully assessed until the mechanisms of immobilization and U speciation in the solid matrix are resolved. However, characterization of the immobilized U and its valence states is extremely difficult, because microbially mediated mineral precipitates are generally nanometer (nm)-sized, poorly crystalline, or amorphous. We are developing combined field emission gun--scanning electron microscopy (FEG-SEM, at Indiana University) and FEG transmission electron microscopy (TEM, at Hopkins) to detect and isolate uranium containing phases; (1) method developments for TEM sample preparations and parallel electron energy loss spectroscopy (EELS) determination of uranium valence; and (2) to determine the speciation, fate, reactivity, valence states of immobilized uranium, using the state-of-the-art 300-kV, FEG-TEM. We have obtained preliminary results on contaminated sediments from Area 3 at the Oak Ridge Field Research Center (FRC). TEM results show that the sediments contain numerous minerals, including quartz, mica/clay (muscovite and/or illite), rutile, ilmenite, zircon, and an Al-Sr-Ce-Ca phosphate mineral, none of which contain uranium above the EDS detection limit. Substantial U (up to ∼2 wt.%) is, however, clearly associated with two materials: (1) the Fe oxyhydroxide and (2) clots of a chemically complex material that is likely a mixture of several nm-scale phases. The Fe oxyhydroxide was identified as goethite from its polycrystalline SAED pattern and EDS analysis showing it to be very Fe-rich; the aggregate also displays one of several morphologies that are common for goethite. U is strongly sorbed to goethite in the FRC sediment, and the ubiquitous association with phosphorous suggests that complexes containing both U and P may play an important role in that sorption. Results from bulk analysis and SEM had previously demonstrated the association of U with Fe and thus suggested that U may be sorbed by Fe oxide or oxyhydroxide (Dr. Roh, image presented by David Watson). However, rigorous identification of the host minerals for U requires TEM results such as these involving imaging, electron diffraction, and spectroscopic analysis. An even higher concentration of U occurs in the chemically complex material noted above. These ''clots'' are high in Fe but also contain C, O, Mg, Al, Si, P, S, Cl, K, Ca, Mn, and U. This chemical complexity strongly suggests that they consist of aggregates of carbonate, silicate, phosphate, and sulfate phases, and TEM images also suggest that they may be intergrowths of numerous exceedingly small nanoparticles. EELS and EFTEM studies should be able to resolve these various components and identify precisely where the uranium is in these complex materials. From the results, it is clear that the FEG-SEM and FEG-TEM can readily detect uranium in the FRC samples. The FEG-SEM allows a wide field of view of the samples and can detect U-rich aggregates as small as 20-30 nm. The FEG-TEM can then focus on these aggregates and use SAED, EDS, EFTEM, and PEELS techniques to determine the valence states, structures, and compositional data for these aggregates. This research will provide a crucial component for a complete understanding of the efficacy of uranium bioremediation.

[en] The accuracy of the forming limit diagram (FLD) determined through Nakazima test is often influenced by non-linear strain path (NLSP) and through-thickness stress. The influence of these factors on measurement accuracy can be weakened or avoided in Marciniak test. But meanwhile, Marciniak test is difficult in operation and possesses poor repeatability. Therefore, the Nakazima test eliminating the influencing factors of accuracy is still an attractive method due to the easy operability and good repeatability. In the present research, two FLDs of aluminium alloy 6014-T4 that were established through Nakazima and Marciniak tests were compared. In order to obtain an accurate FLD in plane-stress state and linear strain paths via Nakazima test, a modified compensation method was applied in Nakazima test to eliminate the interferences of NLSP and through-thickness stress on measuring forming limits. The ultimate strains measured in Nakazima test were transformed to stress-based forming limits through constitutive models to remove the influence of through-thickness stress. Then, the corrected ultimate stresses were transformed back to the limit strains along linear strain paths. Compensated results of Nakazima test showed a good agreement with the experimental results from Marciniak test, proving the validity of this method. Thus, through the easy-operate Nakazima test, an FLD with comparable accuracy to that based on Marciniak test was established. (paper)

[en] Graphical abstract: A new synthetic route leading to polyphosphazene cyclomatrix microsphere with various functional groups has achieved via thiol-ene click modification. Herein, hexacholorocyclophosphazene (HCCP) crosslinked with bisphenol-S and 4,4′-diallyl bisphenol-S to generate broadly dispersed microspheres. Thiol-ene modification under UV irradiation not only presented high efficiency and flexibility for post-functionalization, but also imposed no harm on global morphology and crosslinked skeleton of such microspheres. - Highlights: • Functional polyphosphazene microspheres with high chemical flexibility were synthesized by thiol-ene modification. • Polyphosphazene microspheres possessed high thermal stability. • Glycosylated polyphosphazene microspheres showed affinity to lectin Con-A, which inferred potential application in biomedicine. - Abstract: A new synthetic route leading to functional polyphosphazene cyclomatrix microsphere has been developed via thiol-ene click modification. Hexacholorocyclophosphazene (HCCP) was crosslinked with both bisphenol-S and 4,4′-diallyl bisphenol-S to obtain vinyl polyphosphazene microspheres (VPZM) in order to ensure high crosslinking degree and introduce vinyl moieties. Compared to the microspheres obtained by HCCP and bisphenol-S, the size of VPZM was broadly dispersed from 400 nm to 1.40 μm. Thiol-ene click reactions were carried out to attach functional groups, such as glucosyl, carboxyl, ester and dodecyl groups onto polyphosphazene microspheres, which demonstrated no change in morphology and size after modification. Solid state NMR (SSNMR) and Fourier transform infrared spectoscopy (FT-IR) results showed that the vinyl moieties were introduced in the period of crosslinking and functionalization was also successful via click reactions. Moreover, the microspheres presented a little difference in thermal properties after modification. Concanavalin A (Con-A) fluorescent adsorption was also observed for glucosyl microspheres. Thus, the thiol-ene modified polyphosphazene microspheres displayed chemical flexibility in post-functionalization. These microspheres can be potentially applicated in enzyme immobilization, protein adsorption and chromatographic separation.

[en] Objective: To study the feasibility and the clinical effect of the treatment of tubule pregnancy by using interventional technique through selective uterine artery. Methods: By using seldinger's method, 48 cases received interventional treatment, followed by perfusion of methotrexate (MTX) 100 mg through Tube 4-5 F. The concentration of serum β-HCG, the changes of pelvic cavity, and the open condition of amnion by ultrasonic examination. Results: The cure rate of 47 cases was 97.92%. No serious reaction. After treatment, the mean time that the serum β-HCG concentration returned to normal was 14-28 days and the mean time was 18 days. Conclusion: The treatment of tubule pregnancy by interventional technique proved no harmful effect to reproductive organs and quick recovery. It is worth spreading

[en] The Ginzburg–Landau theory on ferroelectrics with random field induced by dipole defects is studied by using Monte Carlo simulation, in order to investigate the dipole configuration and the dielectric relaxation of relaxor ferroelectrics. With the increase of random field, the dipole configuration evolves from the long-range ferroelectric order into the coexistence of short-range dipole-clusters and less polarized matrix. The dipole-cluster phase above the transition temperature and superparaelectric fluctuations far below this temperature are identified for the relaxor ferroelectrics. We investigate the frequency dispersion and the time-domain spectrum of the dielectric relaxation, demonstrating the Vogel–Fulcher relationship and the multi-peaked time-domain distribution of the dielectric relaxation. (rapid communication)

[en] The surface corrosion of plutonium and δ-Pu-Ga alloy in dry oxygen, water vapour, and humid air overseas was reviewed. Plutonium-oxygen reaction data under these experimental conditions strongly support an idealized model with Pu₂O₃ growth on the metal followed by PuO₂ growth on the Pu₂O₃ layer at low temperature. In vacuum, the PuO₂ reduces to Pu₂O₃ at room temperature at a pressure of 6 × 10^-11 torr. Pu₂O_3-y is formed initially in plutonium-oxygen reaction, not Pu₂O₃ at a pressure of 10^-4 torr. PuO₂ film thickness is thinner than 20 Å at a pressure of 10^-4 torr. The PuO₂ does not reduce to Pu₂O₃ at temperature lower than -20 ℃ at a pressure of 10^-4 torr. The results are helpful for understanding plutonium storage. Plutonium interacts chemically with water vapour to from PuO₂ + H₂. Investigation shows that plutonium dioxide interacts chemically with water and catalytically with oxygen-hydrogen mixtures to form water. Water adsorbs strongly on the oxide below 120 ℃ and desorbs as the temperature is increased to 200 ℃. Hydroxide formed by dissociative adsorption of water promotes formation of the higher oxide (PuO_2+χ) plus H₂, and in the presence of O₂, drives a water-catalyzed cycle that accelerates formation of PuO_2+χ by the PuO₂+O₂ reaction. But some studies exclude the stability of any higher binary Pu oxide PuO_2+χ as a bulk species. The existence of a higher oxide, PuO_2+χ, was recently claimed. Moisture-enhanced oxidation is driven in plutonium with humid air reaction. Plutonium in the water-exposed oxidation rate is increased in the temperature ranges of -25 ℃ -110 ℃ and decreased in the temperature ranges of 110 - 200 ℃, respectively. Oxidation rate of plutonium in the water at temperature of 110 ℃ is the highest. Oxidation rate of plutonium in the water at temperature of above 200 - 215 ℃ is independent on humidity. Ga is located at the surface of Ga-stabilized δ-Pu and is reactive to O₂ exposure to form GaO₂^-. Oxidation rate for Ga-stabilized δ-Pu in dry and moist air is lower than that for pure plutonium. The fabrication and storage of plutonium should be under dry and ambulant air with humidity lower than 2% to decrease oxidation rate for plutonium effectively. Further studies are proposed. (authors)