912 research outputs found
Elevated-temperature impact toughness of Mg–(Gd, Y)–Zr alloy
The Charpy impact results for Mg–10Gd–3Y–0.5Zr and Mg–11Y–5Gd–2Zn–0.5Zr alloys at various temperatures showed that Mg–10Gd–3Y–0.5Zr was more sensitive to temperature. The increase in impact toughness with temperature was related to the blunt crack-tip at high temperatures. The delamination and local melt of matrix were responsible for the brittle-to-ductile transition of GW103 alloy. The branch and bridging of cracks resulting from ordered phases played an import role in the change in fracture mode from cleavage fracture to quasi-cleavage and dimple-fracture for WGZ1152 alloy
Interaction between M2-branes and Bulk Form Fields
We construct the interaction terms between the world-volume fields of
multiple M2-branes and the 3- and 6-form fields in the context of ABJM theory
with U()U() gauge symmetry. A consistency check is made in the
simplest case of a single M2-brane, i.e, our construction matches the known
effective action of M2-brane coupled to antisymmetric 3-form field. We show
that when dimensionally reduced, our couplings coincide with the effective
action of D2-branes coupled to R-R 3- and 5-form fields in type IIA string
theory. We also comment on the relation between a coupling with a specific
6-form field configuration and the supersymmetry preserving mass deformation in
ABJM theory.Comment: 30 pages, version to appear in JHE
Influence of soil properties and test conditions on sorption and desorption of testosterone
In this study, batch sorption and desorption experiments were conducted for testosterone using four agricultural soils and five clay minerals. Significant differences in sorption behavior were observed between abiotic and biotic systems. The Freundlich sorption coefficient Kf (µg per g)/(µg per mL) ranged from 8.53 to 74.46 for soils and from 35.28 to 1243 for clays. The maximum sorption capacity (µg per g) of soils ranged from 25.25 to 440.61 for soils and 168.46 to 499.84 for clays. Correlation of sorption model parameters with soil properties indicated that both clay content and soil organic matter are important variables in predicting testosterone sorption behavior. Observed testosterone desorption from agricultural soils ranged from approximately 14 to 100 percent after 3 desorption cycles, and the desorption percentage decreased as the initial testosterone concentration decreased. Temperature, ionic strength, the water/soil ratio and soil depth were determined to influence sorption and desorption of testosterone. Desorption significantly increase with the soil depth and with the increase in the water to soil ratio. Temperature had an inverse effect on the sorption capacity of the soils tested. Thermodynamic calculations showed that the enthalpy change of the soils tested were the range of 12.9-20.7 kJ per mol, indicating weak interaction between testosterone and soil. Our results suggest that additional studies on how soil particles with different size fractions affect hormones fate and transport are needed in order to determine the potential risk of testosterone leaching or runoff
Contribution of biomimetic collagen-ligand interaction to intrafibrillar mineralization
Contemporary models of intrafibrillar mineralization mechanisms are established using collagen fibrils as templates without considering the contribution from collagen-bound apatite nucleation inhibitors. However, collagen matrices destined for mineralization in vertebrates contain bound matrix proteins for intrafibrillar mineralization. Negatively charged, high\u2013molecular weight polycarboxylic acid is cross-linked to reconstituted collagen to create a model for examining the contribution of collagen-ligand interaction to intrafibrillar mineralization. Cryogenic electron microscopy and molecular dynamics simulation show that, after cross-linking to collagen, the bound polyelectrolyte caches prenucleation cluster singlets into chain-like aggregates along the fibrillar surface to increase the pool of mineralization precursors available for intrafibrillar mineralization. Higher-quality mineralized scaffolds with better biomechanical properties are achieved compared with mineralization of unmodified scaffolds in polyelectrolyte-stabilized mineralization solution. Collagen-ligand interaction provides insights on the genesis of heterogeneously mineralized tissues and the potential causes of ectopic calcification in nonmineralized body tissues
Time-Dependent Fatigue Crack Propagation Behavior of Two Solid-Solution-Strengthened Ni-Based Superalloys—INCONEL 617 and HAYNES 230
The fatigue crack propagation (FCP) as well as the sustained loading crack growth (SLCG) behavior of two solid-solution-strengthened Ni-based superalloys, INCONEL 617 (Special Metals Corporation Family of Companies) and HAYNES 230 (Haynes International, Inc., Kokomo, IN), were studied at increased temperatures in laboratory air under a constant stress-intensity- factor (K) condition. The crack propagation tests were conducted using a baseline cyclic triangular waveform with a frequency of 1 3 Hz. Various hold times were imposed at the maximum load of a fatigue cycle to study the hold time effect. The results show that a linear elastic fracture mechanics (LEFM) parameter, stress intensity factor (K), is sufficient to describe the FCP and SLCG behavior at the testing temperatures ranging from 873 K to 1073 K (600 C to 800 C). As observed in the precipitation-strengthened superalloys, both INCONEL 617 and HAYNES 230 exhibited the time-dependent FCP, steady SLCG behavior, and existence of a damage zone ahead of crack tip. A thermodynamic equation was adapted to correlate the SLCG rates to determine thermal activation energy. The fracture modes associated with crack propagation behavior were discussed, and the mechanism of time-dependent FCP as well as SLCG was identified. Compared with INCONEL 617, the lower crack propagation rates of HAYNES 230 under the time-dependent condition were ascribed to the different fracture mode and the presence of numerous W-rich M6C-type and Cr-rich M23C6-type carbides. Toward the end, a phenomenological model was employed to correlate the FCP rates at cycle/time-dependent FCP domain. All the results suggest that an environmental factor, the stress assisted grain boundary oxygen embrittlement (SAGBOE) mechanism, is mainly responsible for the accelerated time dependent FCP rates of INCONEL 617 and HAYNES 230
Electronic structure of fluorides: general trends for ground and excited state properties
The electronic structure of fluorite crystals are studied by means of density
functional theory within the local density approximation for the exchange
correlation energy. The ground-state electronic properties, which have been
calculated for the cubic structures ,, , ,
, -, using a plane waves expansion of the wave
functions, show good comparison with existing experimental data and previous
theoretical results. The electronic density of states at the gap region for all
the compounds and their energy-band structure have been calculated and compared
with the existing data in the literature. General trends for the ground-state
parameters, the electronic energy-bands and transition energies for all the
fluorides considered are given and discussed in details. Moreover, for the
first time results for have been presented
Integrating fluctuations into distribution of resources in transportation networks
We propose a resource distribution strategy to reduce the average travel time
in a transportation network given a fixed generation rate. Suppose that there
are essential resources to avoid congestion in the network as well as some
extra resources. The strategy distributes the essential resources by the
average loads on the vertices and integrates the fluctuations of the
instantaneous loads into the distribution of the extra resources. The
fluctuations are calculated with the assumption of unlimited resources, where
the calculation is incorporated into the calculation of the average loads
without adding to the time complexity. Simulation results show that the
fluctuation-integrated strategy provides shorter average travel time than a
previous distribution strategy while keeping similar robustness. The strategy
is especially beneficial when the extra resources are scarce and the network is
heterogeneous and lowly loaded.Comment: 14 pages, 4 figure
Azimuthal anisotropy and correlations in p+p, d+Au and Au+Au collisions at 200 GeV
We present the first measurement of directed flow () at RHIC. is
found to be consistent with zero at pseudorapidities from -1.2 to 1.2,
then rises to the level of a couple of percent over the range . The latter observation is similar to data from NA49 if the SPS rapidities
are shifted by the difference in beam rapidity between RHIC and SPS.
Back-to-back jets emitted out-of-plane are found to be suppressed more if
compared to those emitted in-plane, which is consistent with {\it jet
quenching}. Using the scalar product method, we systematically compared
azimuthal correlations from p+p, d+Au and Au+Au collisions. Flow and non-flow
from these three different collision systems are discussed.Comment: Quark Matter 2004 proceeding, 4 pages, 3 figure
Azimuthal anisotropy: the higher harmonics
We report the first observations of the fourth harmonic (v_4) in the
azimuthal distribution of particles at RHIC. The measurement was done taking
advantage of the large elliptic flow generated at RHIC. The integrated v_4 is
about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8)
harmonics upper limits on the magnitudes are reported.Comment: 4 pages, 6 figures, contribution to the Quark Matter 2004 proceeding
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