156 research outputs found
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Novel silica-based ion exchange resin
Shortcomings of chelating resins have been addressed by a new class of ion exchange resins called dual mechanism bifunctional polymers (DMBPs). DMBPs use hydrophilic cation exchange ligands with rapid uptake kinetics and use chelating ligands for selectivity for one or more metals; result is a resin that quickly recognizes and removes targeted metals from waste, remediation, and process streams. Eichrom`s Diphonix {reg_sign} resin is the first DMBP to be widely released as a commercial product; it is polystyrene based. Objective of this work is to synthesize commercial quantities of a silica-based ion exchange resin with the same or better metal ion selectivity, metal uptake kinetics, and acid stability as Diphonix. Feasibility was determined, however the process needs to be optimized. Studies at Eichrom and ANL of the performance of Diphonix resin over a broad range of HNO3 and HCl conditions and inorganic salt loadings are discussed together with the proposed method of incorporating similar characteristics into a silica-based resin. The new, silica-based resin functionalized with diphosphonic acid ligands can be used in environmental restoration and waste management situations involving processing of low-level, transuranic, and high-level radioactive wastes; it can also be used for processing liquid mixed waste including wastes contaminated with organic compounds
Ein einfaches Verfahren zur Herstellung anellierter Thiophene
A simple method for the synthesis of fused thiophenes by reaction of agr-carboxymethyl substituted cyclic ketones withLawesson-reagent is described. Considerations concerning the reaction mechanism are given
Structure Studies of from the Be(d,p) reaction in inverse kinematics on a solid deuteron target
The low-lying structure of Be has remained an enigma for decades.
Despite numerous experimental and theoretical studies, large inconsistencies
remain. Being both unbound, and one neutron away from Be, the heaviest
bound beryllium nucleus, Be is difficult to study through simple
reactions with weak radioactive ion beams or more complex reactions with
stable-ion beams. Here, we present the results of a study using the
Be(d,p)Be reaction in inverse kinematics using a 9.5~MeV per
nucleon Be beam from the ISAC-II facility. The solid deuteron target of
IRIS was used to achieve an increased areal thickness compared to conventional
deuterated polyethylene targets. The Q-value spectrum below -4.4~MeV was
analyzed using a Bayesian method with GEANT4 simulations. A three-point angular
distribution with the same Q-value gate was fit with a mixture of - and
-wave, - and -wave, or pure -wave transfer. The Q-value spectrum
was also compared with GEANT simulations obtained using the energies and widths
of states reported in four previous works. It was found that our results are
incompatible with works that revealed a wide resonance but shows better
agreement with ones that reported a narrower width.Comment: 10 pages, 5 figure
Study of 3He(n,p)3H reaction at cosmological energies with trojan horse method
In the network of reactions present in the Big Bang nucleosynthesis, the 3He(n, p)3H has an important role which impacts the final 7Li abundance. The Trojan Horse Method (THM) has been applied to the 3He(d, pt)H reaction in order to extract the astrophysical S(E)-factor of the 3He(n, p)3H in the Gamow energy range. The experiment will be described in the present work together with the first preliminary results
Contribution of topographically-generated submesoscale turbulence to Southern Ocean overturning
The ocean’s global overturning circulation regulates the transport and storage of heat, carbon and nutrients. Upwelling across the Southern Ocean’s Antarctic Circumpolar Current and into the mixed layer, coupled to water mass modification by surface buoyancy forcing, has been highlighted as a key process in the closure of the overturning circulation. Here, using twelve high-resolution hydrographic sections in southern Drake Passage, collected with autonomous ocean gliders, we show that Circumpolar Deep Water originating from the North Atlantic, known as Lower Circumpolar Deep Water, intersects sloping topography in narrow and strong boundary currents. Observations of strong lateral buoyancy gradients, enhanced bottom turbulence, thick bottom mixed layers and modified water masses are consistent with growing evidence that topographically generated submesoscale flows over continental slopes enhance near-bottom mixing, and that cross-density upwelling occurs preferentially over sloping topography. Interactions between narrow frontal currents and topography occur elsewhere along the path of the Antarctic Circumpolar Current, which leads us to propose that such interactions contribute significantly to the closure of the overturning in the Southern Ocean
Submesoscale cyclones in the Agulhas current
Gliders were deployed for the first time in the Agulhas Current region to investigate processes of interactions between western boundary currents and shelf waters. Continuous observations from the gliders in water depths of 100-1000m and over a period of 1month provide the first high-resolution observations of the Agulhas Current's inshore front. The observations collected in a nonmeandering Agulhas Current show the presence of submesoscale cyclonic eddies, generated at the inshore boundary of the Agulhas Current. The submesoscale cyclones are often associated with warm water plumes, which extend from their western edge and exhibit strong northeastward currents. These features are a result of shear instabilities and extract their energy from the mean Agulhas Current jet
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