523 research outputs found
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Optimization of magnetite carrier precipitation process for transuranic waste reduction
Transuranic (TRU) waste that is being generated at Argonne National Laboratory has a TRU activity ranging from 10{sup 2} to 10{sup 7} nCi/g with a wide variety of chemical compositions. Currently, the waste is stored in highly acidic solutions that must be neutralized for intermediate storage. A magnetite carrier precipitation process has been adapted to concentrate TRU isotopes in a noncorrosive solid phase. In this paper, the authors report the results of a series of laboratory tests done to optimize the process. The parameters they optimized included (1) magnetite concentration used to precipitate the TRUs from solution, (2) formation of magnetite (in situ or ex situ), (3) processing pH, and (4) temperature and mixing time of the carrier precipitation. They also studied the effects of anions, cations, and complexing agents in the waste solutions on the carrier precipitation and the effect of magnetite solids loading on the filtration equipment. An overview is given of the planned full-scale process, which will be operated in a glovebox
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The release of cesium and the actinides from spent fuel under unsaturated conditions
Tests designed to be similar to the unsaturated and oxidizing conditions expected in the candidate repository at Yucca Mountain are in progress with spent fuel at 90{degree}C. The similarities and the differences in release behavior for {sup 137}Cs during the first 2.6 years and the actinides during the first 1.6 years of testing are presented for tests done with (1) water dripped on the fuel at a rate of 0.075 and 0.75 mL every 3.5 days and (2) in a saturated water vapor environment
Multiple (inverse) binomial sums of arbitrary weight and depth and the all-order epsilon-expansion of generalized hypergeometric functions with one half-integer value of parameter
We continue the study of the construction of analytical coefficients of the
epsilon-expansion of hypergeometric functions and their connection with Feynman
diagrams. In this paper, we show the following results:
Theorem A: The multiple (inverse) binomial sums of arbitrary weight and depth
(see Eq. (1.1)) are expressible in terms of Remiddi-Vermaseren functions.
Theorem B: The epsilon expansion of a hypergeometric function with one
half-integer value of parameter (see Eq. (1.2)) is expressible in terms of the
harmonic polylogarithms of Remiddi and Vermaseren with coefficients that are
ratios of polynomials. Some extra materials are available via the www at this
http://theor.jinr.ru/~kalmykov/hypergeom/hyper.htmlComment: 24 pages, latex with amsmath and JHEP3.cls; v2: some typos corrected
and a few references added; v3: few references added
Anisotropic Superexchange for nearest and next nearest coppers in chain, ladder and lamellar cuprates
We present a detailed calculation of the magnetic couplings between
nearest-neighbor and next-nearest-neighbor coppers in the edge-sharing
geometry, ubiquitous in many cuprates. In this geometry, the interaction
between nearest neighbor coppers is mediated via two oxygens, and the Cu-O-Cu
angle is close to 90 degrees. The derivation is based on a perturbation
expansion of a general Hubbard Hamiltonian, and produces numerical estimates
for the various magnetic energies. In particular we find the dependence of the
anisotropy energies on the angular deviation away from the 90 degrees geometry
of the Cu-O-Cu bonds. Our results are required for the correct analysis of the
magnetic structure of various chain, ladder and lamellar cuprates.Comment: 13 pages, Latex, 7 figure
Itinerant Ferromagnetism in the Periodic Anderson Model
We introduce a novel mechanism for itinerant ferromagnetism, based on a
simple two-band model. The model includes an uncorrelated and dispersive band
hybridized with a second band which is narrow and correlated. The simplest
Hamiltonian containing these ingredients is the Periodic Anderson Model (PAM).
Using quantum Monte Carlo and analytical methods, we show that the PAM and an
extension of it contain the new mechanism and exhibit a non-saturated
ferromagnetic ground state in the intermediate valence regime. We propose that
the mechanism, which does not assume an intra atomic Hund's coupling, is
present in both the iron group and in some f electron compounds like
Ce(Rh_{1-x} Ru_x)_3 B_2, La_x Ce_{1-x} Rh_3 B_2 and the uranium
monochalcogenides US, USe, and UTe
Leading for gold: social identity leadership processes at the London 2012 Olympic Games
© 2014, © 2014 Taylor & Francis. This paper adopted a social identity approach to explore the media data of leadership figures at the London 2012 Olympic Games. Media data in the form of interviews, speeches/team announcements, and blog posts from leaders integral to the London 2012 Olympic Games were analysed from 100 days prior to, during, and for 30 days following, the Olympic Games. Leaders included Lord Seb Coe, Andy Hunt, and performance directors of TeamGB athletics (Charles van Commenee), cycling (Sir David Brailsford), rowing (David Tanner) and swimming (Michael Scott). An inductive and deductive thematic analysis identified five higher order themes: creation of team identities, team values, team vision, performance consequences and ‘we’ achieved. The analysis makes a contribution to extant leadership literature by highlighting novel contextually relevant themes surrounding leadership at the London 2012 Olympic Games. Thus, opportunities for future research and application are outlined
A general purpose package (MADFOMS) for predicting the morphologies and powder X-ray diffraction patterns of molecular crystals
Search for the Rare Decay KL --> pi0 ee
The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay
KL--> pi0ee. This mode is expected to have a significant CP violating
component. The measurement of its branching ratio could support the Standard
Model or could indicate the existence of new physics. This letter reports new
results from the 1999-2000 data set. One event is observed with an expected
background at 0.99 +/- 0.35 events. We set a limit on the branching ratio of
3.5 x 10^(-10) at the 90% confidence level. Combining the results with the
dataset taken in 1997 yields the final KTeV result: BR(KL --> pi0 ee) < 2.8 x
10^(-10) at 90% CL.Comment: 4 pages, three figure
ALICE: The Ultraviolet Imaging Spectrograph aboard the New Horizons Pluto-Kuiper Belt Mission
The New Horizons ALICE instrument is a lightweight (4.4 kg), low-power (4.4
Watt) imaging spectrograph aboard the New Horizons mission to Pluto/Charon and
the Kuiper Belt. Its primary job is to determine the relative abundances of
various species in Pluto's atmosphere. ALICE will also be used to search for an
atmosphere around Pluto's moon, Charon, as well as the Kuiper Belt Objects
(KBOs) that New Horizons hopes to fly by after Pluto-Charon, and it will make
UV surface reflectivity measurements of all of these bodies as well. The
instrument incorporates an off-axis telescope feeding a Rowland-circle
spectrograph with a 520-1870 angstroms spectral passband, a spectral point
spread function of 3-6 angstroms FWHM, and an instantaneous spatial
field-of-view that is 6 degrees long. Different input apertures that feed the
telescope allow for both airglow and solar occultation observations during the
mission. The focal plane detector is an imaging microchannel plate (MCP) double
delay-line detector with dual solar-blind opaque photocathodes (KBr and CsI)
and a focal surface that matches the instrument's 15-cm diameter
Rowland-circle. In what follows, we describe the instrument in greater detail,
including descriptions of its ground calibration and initial in flight
performance.Comment: 24 pages, 29 figures, 2 tables; To appear in a special volume of
Space Science Reviews on the New Horizons missio
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