Showing papers by "Chalk River Laboratories published in 2016"
TL;DR: In this article, a 3D transient fully coupled thermomechanical model was built to study the distortion and residual stress in electron beam additive manufactured Ti-6Al-4V build plates.
150 citations
TL;DR: In this article, the authors investigated the oxidation behavior of several stainless steels and nickel-based superalloys exposed to supercritical water at 800°C for 12h and found that the thickness of the oxide layers formed was as high as 1μm, comprising different spinel structures.
105 citations
TL;DR: Infrared spectroscopy and powder neutron diffraction experiments were used to confirm this mechanism of selective O2 binding, and gas adsorption measurements also reveal excellent O2 /N2 selectivity with substantial O2 reversibility at room temperature.
Abstract: A chromium(II)-based metal-organic framework Cr3 [(Cr4 Cl)3 (BTT)8 ]2 (Cr-BTT; BTT(3-) =1,3,5-benzenetristetrazolate), featuring coordinatively unsaturated, redox-active Cr(2+) cation sites, was synthesized and investigated for potential applications in H2 storage and O2 production. Low-pressure H2 adsorption and neutron powder diffraction experiments reveal moderately strong Cr-H2 interactions, in line with results from previously reported M-BTT frameworks. Notably, gas adsorption measurements also reveal excellent O2 /N2 selectivity with substantial O2 reversibility at room temperature, based on selective electron transfer to form Cr(III) superoxide moieties. Infrared spectroscopy and powder neutron diffraction experiments were used to confirm this mechanism of selective O2 binding.
97 citations
TL;DR: It is shown that in non-collinear antiferromagnets, a strong magnon–phonon coupling can significantly enhance the anharmonicity, resulting in the creation of magnetoelastic excitations and their spontaneous decay.
Abstract: Magnons and phonons are fundamental quasiparticles in a solid and can be coupled together to form a hybrid quasi-particle. However, detailed experimental studies on the underlying Hamiltonian of this particle are rare for actual materials. Moreover, the anharmonicity of such magnetoelastic excitations remains largely unexplored, although it is essential for a proper understanding of their diverse thermodynamic behaviour and intrinsic zero-temperature decay. Here we show that in non-collinear antiferromagnets, a strong magnon-phonon coupling can significantly enhance the anharmonicity, resulting in the creation of magnetoelastic excitations and their spontaneous decay. By measuring the spin waves over the full Brillouin zone and carrying out anharmonic spin wave calculations using a Hamiltonian with an explicit magnon-phonon coupling, we have identified a hybrid magnetoelastic mode in (Y,Lu)MnO3 and quantified its decay rate and the exchange-striction coupling term required to produce it.
69 citations
TL;DR: In oxygenated tumor and normal cells, mitochondria, rather than the nucleus, are the primary loci of radiotherapy effects, especially for low linear energy transfer radiation, which can be explained by radiation-induced effects in mitochondria that generate reactive oxygen species, which in turn indirectly target nuclear DNA.
Abstract: // Richard B. Richardson 1,2 and Mary-Ellen Harper 3 1 Canadian Nuclear Laboratories (CNL), Radiobiology and Health, Chalk River Laboratories, Chalk River, ON, Canada 2 McGill Medical Physics Unit, Cedars Cancer Center-Glen Site, Montreal, QC, Canada 3 Department of Biochemistry Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada Correspondence to: Richard B. Richardson, email: // Keywords : mitochondria, oxidative stress, oxygen effect, radiation therapy, therapy resistance Received : November 04, 2015 Accepted : January 29, 2016 Published : February 15, 2016 Abstract It has been more than 60 years since the discovery of the oxygen effect that empirically demonstrates the direct association between cell radiosensitivity and oxygen tension, important parameters in radiotherapy. Yet the mechanisms underlying this principal tenet of radiobiology are poorly understood. Better understanding of the oxygen effect may explain difficulty in eliminating hypoxic tumor cells, a major cause of regrowth after therapy. Our analysis utilizes the Howard-Flanders and Alper formula, which describes the relationship of radiosensitivity with oxygen tension. Here, we assign and qualitatively assess the relative contributions of two important mechanisms. The first mechanism involves the emission of reactive oxygen species from the mitochondrial electron transport chain, which increases with oxygen tension. The second mechanism is related to an energy and repair deficit, which increases with hypoxia. Following a radiation exposure, the uncoupling of the oxidative phosphorylation system (proton leak) in mitochondria lowers the emission of reactive oxygen species which has implications for fractionated radiotherapy, particularly of hypoxic tumors. Our analysis shows that, in oxygenated tumor and normal cells, mitochondria, rather than the nucleus, are the primary loci of radiotherapy effects, especially for low linear energy transfer radiation. Therefore, the oxygen effect can be explained by radiation-induced effects in mitochondria that generate reactive oxygen species, which in turn indirectly target nuclear DNA.
57 citations
TL;DR: These releases were detected by monitoring stations throughout Japan, and from these measurements, key insights can be made about the different chemical forms that were released, as well as the persistence of each in the environment.
49 citations
TL;DR: The results not only justify a low-cost, efficient and reliable hydrothermal synthesis method for LiFePO4 but also provide a promising alternative viewpoint on the mechanism controlling the nanosizing of Li FePO4, which leads to improved electrochemical performances.
Abstract: Based on neutron powder diffraction (NPD) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), we show that calcium ions help eliminate the Fe-antisite defects by controlling the nucleation and evolution of the LiFePO4 particles during their hydrothermal synthesis. This Ca-regulated formation of LiFePO4 particles has an overwhelming impact on the removal of their iron antisite defects during the subsequent carbon-coating step since (i) almost all the Fe-antisite defects aggregate at the surface of the LiFePO4 crystal when the crystals are small enough and (ii) the concomitant increase of the surface area, which further exposes the Fe-antisite defects. Our results not only justify a low-cost, efficient and reliable hydrothermal synthesis method for LiFePO4 but also provide a promising alternative viewpoint on the mechanism controlling the nanosizing of LiFePO4, which leads to improved electrochemical performances.
45 citations
TL;DR: In this article, a heat transfer correlation for supercritical fluid was developed based on experimental data, which indicated that the steep gradient of physical property over the tube cross-section is the key reason for heat transfer deterioration.
41 citations
TL;DR: It is demonstrated that NaFe1−xCuxAs near x≈0.5 exhibits real space Fe and Cu ordering, and are antiferromagnetic insulators with the insulating behaviour persisting above the Néel temperature, indicative of a Mott insulator.
Abstract: Iron-based superconductivity develops near an antiferromagnetic order and out of a bad-metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can be realized in the phase diagram of the iron pnictides remains an open question. Here we use transport, transmission electron microscopy, X-ray absorption spectroscopy, resonant inelastic X-ray scattering and neutron scattering to demonstrate that NaFe1-xCuxAs near x≈0.5 exhibits real space Fe and Cu ordering, and are antiferromagnetic insulators with the insulating behaviour persisting above the Neel temperature, indicative of a Mott insulator. On decreasing x from 0.5, the antiferromagnetic-ordered moment continuously decreases, yielding to superconductivity ∼x=0.05. Our discovery of a Mott-insulating state in NaFe1-xCuxAs thus makes it the only known Fe-based material, in which superconductivity can be smoothly connected to the Mott-insulating state, highlighting the important role of electron correlations in the high-Tc superconductivity.
41 citations
TL;DR: In this paper, powder spray laser additive manufacturing technology was used to deposit commercially pure zirconium on ZIRconium alloy substrates and the clad quality was assessed based on deposition rate, dilution, geometrical circularity and presence of defects.
41 citations
TL;DR: In this article, a 2 × 2 wire-wrapped rod bundle was used to simulate a fuel assembly with four heated rods and the results showed that the correlations of Jackson and Krasnoshchekov-Protopopov gave the best predictions on average Nusselt number.
TL;DR: Double perovskites of the general formula Ba2MReO6, where M = Mg, Zn, and Y2/3, all based on Re6+, were synthesized and studied using magnetization, heat capacity, muon spin relaxation, and neutron-scattering techniques, and the computed heat capacity predicts the two maxima observed experimentally.
Abstract: Double perovskites (DP) of the general formula Ba2MReO6, where M = Mg, Zn, and Y2/3, all based on Re6+ (5d1, t2g1), were synthesized and studied using magnetization, heat capacity, muon spin relaxation, and neutron-scattering techniques. All are cubic, Fm3m, at ambient temperature to within the resolution of the X-ray and neutron diffraction data, although the muon data suggest the possibility of a local distortion for M = Mg. The M = Mg DP is a ferromagnet, Tc = 18 K, with a saturation moment ∼0.3 bohr magnetons at 3 K. There are two anomalies in the heat capacity: a sharp feature at 18 K and a broad maximum centered near 33 K. The total entropy loss below 45 K is 9.68 e.u., which approaches R ln 4 (11.52 e.u.) supporting a j = 3/2 ground state. The unit cell constants of Ba2MgReO6 and the isostructural, isoelectronic analogue, Ba2LiOsO6, differ by only 0.1%, yet the latter is an anti-ferromagnet. The M = Zn DP also appears to be a ferromagnet, Tc = 11 K, μsat(Re) = 0.1 μB. In this case the heat capacit...
TL;DR: In this article, three closely related double perovskites (DPs) based on the $5{d}^{2}$ ion, including cubic, Fm-$3m, at ambient temperature from x-ray (XRD) and neutron diffraction (ND), have been prepared and characterized using dc magnetization, heat capacity, and muon spin relaxation.
Abstract: Three closely related double perovskites (DP) based on the $5{d}^{2}$ ion, $\mathrm{O}{\mathrm{s}}^{6+},\mathrm{B}{\mathrm{a}}_{2}M\mathrm{Os}{\mathrm{O}}_{6}$, with $M=\mathrm{Mg}$, Zn, and Cd have been prepared and characterized using x-ray (XRD) and neutron diffraction (ND), dc magnetization, heat capacity, and muon spin relaxation $(\ensuremath{\mu}\mathrm{SR})$ techniques All three are cubic, Fm-$3m$, at ambient temperature from XRD with $\mathrm{\ensuremath{\Delta}}d/d\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ resolution For both $M=\mathrm{Mg}$ and Zn, ND data at 35 K and lower, $\mathrm{\ensuremath{\Delta}}d/d=2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, resolution show no signs of a distortion The results are compared with the known DP material, $\mathrm{B}{\mathrm{a}}_{2}\mathrm{CaOs}{\mathrm{O}}_{6}$, which shows antiferromagnetic (AF) order below ${T}_{\mathrm{N}}=49\phantom{\rule{016em}{0ex}}\mathrm{K}$ and a moderate frustration index, $f\ensuremath{\sim}4$, $(f=|{\ensuremath{\theta}}_{\mathrm{CW}}|/{T}_{\mathrm{N}})$, where ${\ensuremath{\theta}}_{\mathrm{CW}}$ is the Curie-Weiss temperature $\mathrm{B}{\mathrm{a}}_{2}\mathrm{MgOs}{\mathrm{O}}_{6}$ with a unit cell constant ${a}_{0}=80757(1)\phantom{\rule{016em}{0ex}}\AA{}$, 3% smaller than for $\mathrm{B}{\mathrm{a}}_{2}\mathrm{CaOs}{\mathrm{O}}_{6}$, also shows N\'eel order below ${T}_{\mathrm{N}}=51\phantom{\rule{016em}{0ex}}\mathrm{K}$ with $f\ensuremath{\sim}2$ However, $\mathrm{B}{\mathrm{a}}_{2}\mathrm{ZnOs}{\mathrm{O}}_{6},{a}_{0}=80975(1)\phantom{\rule{016em}{0ex}}\AA{}$, 027% larger than $\mathrm{B}{\mathrm{a}}_{2}\mathrm{MgOs}{\mathrm{O}}_{6}$, does not show N\'eel order from either heat capacity or $\ensuremath{\mu}\mathrm{SR}$ data A zero field cooled/field cooled (ZFC/FC) irreversibility occurs near 30 K and a broad heat capacity anomaly is detected at a similar temperature The $\ensuremath{\mu}\mathrm{SR}$ data are consistent with a weak spin ordering with an onset below 28 K but with a coexisting dynamic component $\mathrm{B}{\mathrm{a}}_{2}\mathrm{CdOs}{\mathrm{O}}_{6}$ with ${a}_{0}=83190(1)\phantom{\rule{016em}{0ex}}\AA{}$, 05% smaller than $\mathrm{B}{\mathrm{a}}_{2}\mathrm{CaOs}{\mathrm{O}}_{6}$, shows no evidence for any type of order/spin freezing to 047 K from any of the measurement techniques applied The results for $M=\mathrm{Zn}$ and Cd appear to lie outside of the mean field theory of Chen and Balents [Phys Rev B 84, 094420 (2011)] for cubic ${d}^{2}$ DP with strong spin orbit coupling, but $\mathrm{B}{\mathrm{a}}_{2}\mathrm{MgOs}{\mathrm{O}}_{6}$, along with $\mathrm{B}{\mathrm{a}}_{2}\mathrm{CaOs}{\mathrm{O}}_{6}$, is likely one of the three predicted AF phases The remarkable contrast between the doppelg\"anger pairs $M=\mathrm{Mg}$/Zn and $M=\mathrm{Ca}$/Cd may be traceable to differences in electronic structure of the diamagnetic $M$ ions All of the super-super exchange pathways in these DP materials involve Os--O--$M$--O--Os linkages
TL;DR: In this article, the authors monitored the initial stages of oxidation in Alloy 800H tubes exposed to oxygenated supercritical water and found that no Cr release was observed during these initial stages, attributed to Mn incorporation in the oxide.
TL;DR: In this article, a three-dimensional Computational Fluid Dynamics (CFD) tool (STAR-CCM+) was used to model the single phase flow through a cold 5-by-5 rod bundle with a split-vane spacer grid.
TL;DR: The results support the notion of a bone marrow microenvironment characterized by increased propensity toward adipogenesis in AML, which may negatively impact normal hematopoiesis.
Abstract: The role of bone marrow-derived mesenchymal stem/stromal cells (MSCs) in creating a permissive microenvironment that supports the emergence and progression of acute myeloid leukemia (AML) is not well established. We investigated the extent to which adipogenic differentiation in normal MSCs alters hematopoietic supportive capacity and we undertook an in-depth comparative study of human bone marrow MSCs derived from newly diagnosed AML patients and healthy donors, including an assessment of adipogenic differentiation capacity. MSCs from healthy controls with partial induction of adipogenic differentiation, in comparison to MSCs undergoing partial osteogenic differentiation, expressed increased levels of hematopoietic factors and induced greater proliferation, decreased quiescence and reduced in vitro hematopoietic colony forming capacity of CD34+ hematopoietic stem and progenitor cells (HSPCs). Moreover, we observed that AML-derived MSCs had markedly increased adipogenic potential and delayed osteogenic differentiation, while maintaining normal morphology and viability. AML-derived MSCs, however, possessed reduced proliferative capacity and decreased frequency of subendothelial quiescent MSCs compared to controls. Our results support the notion of a bone marrow microenvironment characterized by increased propensity toward adipogenesis in AML, which may negatively impact normal hematopoiesis. Larger confirmatory studies are needed to understand the impact of various clinical factors. Novel leukemia treatments aimed at normalizing bone marrow niches may enhance the competitive advantage of normal hematopoietic progenitors over leukemia cells.
TL;DR: In this article, Alloy 600 (Ni-16Cr-9Fe) and Alloy 800 (Fe-35Ni-23Cr) were exposed to simulated primary water at 315°C.
01 Jun 2016-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors compared GEANT4 with MCNPX in the characterization of a boron-lined neutron detector and showed that MCNPx results are more self-consistent than are GEant4 results, by 3-4%.
Abstract: This work compares GEANT4 with MCNPX in the characterization of a boron-lined neutron detector. The neutron energy ranges simulated in this work (0.025 eV to 20 MeV) are the traditional domain of MCNP simulations. This paper addresses the question, how well can GEANT4 and MCNPX be employed for detailed thermal neutron detector characterization? To answer this, GEANT4 and MCNPX have been employed to simulate detector response to a 252 Cf energy spectrum point source, as well as to simulate mono-energetic parallel beam source geometries. The 252 Cf energy spectrum simulation results demonstrate agreement in detector count rate within 3% between the two packages, with the MCNPX results being generally closer to experiment than are those from GEANT4. The mono-energetic source simulations demonstrate agreement in detector response within 5% between the two packages for all neutron energies, and within 1% for neutron energies between 100 eV and 5 MeV. Cross-checks between the two types of simulations using ISO-8529 252 Cf energy bins demonstrates that MCNPX results are more self-consistent than are GEANT4 results, by 3–4%.
TL;DR: In this article, a fuel performance code for light water reactors called CityU Advanced Multiphysics Nuclear Fuels Performance with User-defined Simulations (CAMPUS) was developed.
TL;DR: The discussion presented here details the planning and execution of the trials, outlines the relevant radiation safety aspects, provides a summary of the source term and atmospheric conditions for the three dispersal events, and provides an overview of the measurements that were made to track the plumes and deposition patterns.
Abstract: In 2012, Defence Research and Development Canada, in partnership with a number of other Canadian and International organizations, led a series of three field trials designed to simulate a Radiological Dispersal Device (RDD). These trials, known as the Full-Scale RDD (FSRDD) Field Trials, involved the explosive dispersal of a short-lived radioactive tracer ((140)La, t1/2 = 40.293 h). The FSRDD Field Trials required a significant effort in their planning, preparation, and execution to ensure that they were carried out in a safe, efficient manner and that the scientific goals of the trials were met. The discussion presented here details the planning and execution of the trials, outlines the relevant radiation safety aspects, provides a summary of the source term and atmospheric conditions for the three dispersal events, and provides an overview of the measurements that were made to track the plumes and deposition patterns.
TL;DR: In this paper, the authors carried out detailed studies of the magnetic structure, magnetoelastic coupling, and thermal properties of nanopowders from room temperature to liquid helium temperature.
Abstract: We carried out detailed studies of the magnetic structure, magnetoelastic coupling, and thermal properties of ${\mathrm{EuCrO}}_{3}$ nanopowders from room temperature to liquid helium temperature. Our neutron powder diffraction and x-ray powder diffraction measurements provide precise atomic positions of all atoms in the cell, especially for the light oxygen atoms. The low-temperature neutron powder diffraction data revealed extra Bragg peaks of magnetic origin, which can be attributed to a ${G}_{x}$ antiferromagnetic structure with an ordered moment of $\ensuremath{\sim}2.4{\ensuremath{\mu}}_{\mathrm{B}}$ consistent with the $3{d}^{3}$ electronic configuration of the ${\mathrm{Cr}}^{3+}$ cations. Apart from previously reported antiferromagnetic and ferromagnetic transitions in ${\mathrm{EuCrO}}_{3}$ at low temperatures, we also observed an anomaly at about 100 K. This anomaly was observed in the temperature dependence of the sample's, lattice parameters, thermal expansion, Raman spectroscopy, permittivity, and conductance measurements. This anomaly is attributed to the magnetoelastic distortion in the ${\mathrm{EuCrO}}_{3}$ crystal.
TL;DR: In this article, the oxide scale grown of static capsules made of alloy 310S stainless steel was investigated by exposure to supercritical water at 500 ÂC 25 ÂMPa for various exposure times up to 20,000 h.
TL;DR: In this article, a 3D CFD study of the fluid flow and heat transfer at supercritical pressures for the rod bundle geometries was performed with the key parameter being the fuel rod wall temperature.
TL;DR: In this paper, the frustrated double perovskite was studied using magnetization, elastic neutron scattering, heat capacity, and muon spin relaxation (\ensuremath{\mu}SR) techniques and compared with isostructural $(P{2}_{1}/n):
Abstract: The frustrated double perovskite $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiOs}{\mathrm{O}}_{6}$, based on $\mathrm{O}{\mathrm{s}}^{5+}\phantom{\rule{0.16em}{0ex}}(5{d}^{3},\phantom{\rule{0.16em}{0ex}}{\mathrm{t}}_{2}^{3})$ is studied using magnetization, elastic neutron scattering, heat capacity, and muon spin relaxation (\ensuremath{\mu}SR) techniques and compared with isostructural $(P{2}_{1}/n)\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiRu}{\mathrm{O}}_{6},\phantom{\rule{0.16em}{0ex}}\mathrm{R}{\mathrm{u}}^{5+}(4{d}^{3},\phantom{\rule{0.16em}{0ex}}{\mathrm{t}}_{2}^{3})$. While previous studies of $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiOs}{\mathrm{O}}_{6}$ showed a broad susceptibility maximum $({\ensuremath{\chi}}_{\mathrm{max}})$ near 40 K, heat capacity data indicate a sharp peak at 30 K, similar to $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiRu}{\mathrm{O}}_{6}$ with ${\ensuremath{\chi}}_{\mathrm{max}}\ensuremath{\sim}30\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and a heat capacity peak at 24 K. Significant differences between the two materials are seen in powder neutron diffraction where the magnetic structure is described by $\mathbit{k}=(1/2\phantom{\rule{0.16em}{0ex}}1/2\phantom{\rule{4pt}{0ex}}0)$ for $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiOs}{\mathrm{O}}_{6}$, while $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiRu}{\mathrm{O}}_{6}$ has been reported with $\mathbit{k}=(000)$, structure for face centered lattices. For the $\mathbit{k}=(1/2\phantom{\rule{0.16em}{0ex}}1/2\phantom{\rule{4pt}{0ex}}0)$ structure, one has antiferromagnetic layers stacked antiferromagnetically, while for $\mathbit{k}=(0\phantom{\rule{0.16em}{0ex}}0\phantom{\rule{0.16em}{0ex}}0)$ structure, ferromagnetic layers are stacked antiferromagnetically. In spite of these differences, both can be considered as type I fcc antiferromagnetic structures. For $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiOs}{\mathrm{O}}_{6}$, the magnetic structure is best described in terms of linear combinations of basis vectors belonging to irreducible representations ${\mathrm{\ensuremath{\Gamma}}}_{2}$ and ${\mathrm{\ensuremath{\Gamma}}}_{4}$. The combinations ${\mathrm{\ensuremath{\Gamma}}}_{2}--{\mathrm{\ensuremath{\Gamma}}}_{4}$ and ${\mathrm{\ensuremath{\Gamma}}}_{2}+{\mathrm{\ensuremath{\Gamma}}}_{4}$ could not be distinguished from refinement of the data. In all cases, the $\mathrm{O}{\mathrm{s}}^{5+}$ moments lie in the $yz$ plane with the largest component along $y$. The total moment is 1.81(4) ${\ensuremath{\mu}}_{\mathrm{B}}$. For $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiRu}{\mathrm{O}}_{6}$, the $\mathrm{R}{\mathrm{u}}^{5+}$ moments are reported to lie in the $xz$ plane. In addition, while neutron diffraction, \ensuremath{\mu}SR and NMR data indicate a unique ${T}_{\mathrm{N}}=24\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ for $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiRu}{\mathrm{O}}_{6}$, the situation for $\mathrm{L}{\mathrm{a}}_{2}\mathrm{LiOs}{\mathrm{O}}_{6}$ is more complex, with heat capacity, neutron diffraction, and \ensuremath{\mu}SR indicating two ordering events at 30 and 37 K, similar to the cases of cubic $\mathrm{B}{\mathrm{a}}_{2}\mathrm{YRu}{\mathrm{O}}_{6}$ and monoclinic $\mathrm{S}{\mathrm{r}}_{2}\mathrm{YRu}{\mathrm{O}}_{6}$.
TL;DR: The crystal structure of KRuO4 is refined at both 280 and 3.5 K from neutron powder data, and magnetic properties are reported for the first time, and it is unclear that the origin of the short-range spin correlations is also not understood.
Abstract: The crystal structure of KRuO4 is refined at both 280 and 3.5 K from neutron powder data, and magnetic properties are reported for the first time. The scheelite structure, I41/a, is confirmed at both temperatures. Atomic positions of greater accuracy than the original 1954 X-ray study are reported. The rare Ru7+ ion resides in a site of distorted tetrahedral symmetry with nominal electronic configuration 4d1(e1). Curie–Weiss parameters are near free ion values for the effective moment and θ = −77 K, indicating dominant antiferromagnetic (AF) correlations. A broad susceptibility maximum occurs near 34 K, but long-range AF order sets in only below 22.4 K as determined by magnetization and heat capacity data. The entropy loss below 50 K is only 44% of the expected R ln 2, indicating the presence of short-range spin correlations over a wide temperature range. The Ru sublattice consists of centered, corner-sharing tetrahedra which can lead to geometric frustration if both the nearest-neighbor, J1, and the next...
TL;DR: In this paper, the effects of Ni:Co and Al:Ti ratios on the room temperature microstructure, hardness and lattice parameter of twenty-seven quinary Ni-Co-Al-Ti-Cr alloys have been evaluated.
TL;DR: Software, the Automated Dicentric Chromosome Identifier (ADCI), is presented which detects and discriminates DCs from monocentric chromosomes, computes biodosimetry calibration curves and estimates radiation dose.
Abstract: The dose from ionizing radiation exposure can be interpolated from a calibration curve fit to the frequency of dicentric chromosomes (DCs) at multiple doses. As DC counts are manually determined, there is an acute need for accurate, fully automated biodosimetry calibration curve generation and analysis of exposed samples. Software, the Automated Dicentric Chromosome Identifier (ADCI), is presented which detects and discriminates DCs from monocentric chromosomes, computes biodosimetry calibration curves and estimates radiation dose. Images of metaphase cells from samples, exposed at 1.4-3.4 Gy, that had been manually scored by two reference laboratories were reanalyzed with ADCI. This resulted in estimated exposures within 0.4-1.1 Gy of the physical dose. Therefore, ADCI can determine radiation dose with accuracies comparable to standard triage biodosimetry. Calibration curves were generated from metaphase images in ~10 h, and dose estimations required ~0.8 h per 500 image sample. Running multiple instances of ADCI may be an effective response to a mass casualty radiation event.
TL;DR: In this paper, the authors used the EVPSC-TDT model for polycrystal plasticity and in-situ neutron diffraction to investigate the behavior of a Mg-8.5wt.%Al alloy with two starting textures.
TL;DR: The highest biases of (90)Sr determination were due to lower activity concentrations of (89)SR and are regarded as acceptable in emergency situations with elevated levels of radiostrontium in the sample.
TL;DR: It is found that slimy sculpin grew faster in the regulated Magpie River than in nearby unregulated systems, whereas growth in the Michipicoten River was intermediate, and differences in sculpins life history traits within rivers closely followed spatial patterns in food availability.
Abstract: Hydroelectric facilities can dramatically alter the quantity and quality of fish habitat; however it is not well known how these habitat changes affect the growth and life history of fish. We examine the growth and life history of slimy sculpin (Cottus cognatus), a small-bodied sedentary, benthic stream fish, in two regulated and eight unregulated tributaries of Lake Superior, Canada. Among rivers, we found that slimy sculpin grew faster in the regulated Magpie River than in nearby unregulated systems, whereas growth in the Michipicoten River was intermediate. Sculpin were also in better condition in the regulated Magpie and Michipicoten than in nearby natural rivers. Faster growth of sculpin, however, potentially led to their rapid maturity and higher instantaneous mortality in regulated rivers. Within the regulated rivers, there are strong longitudinal gradients in growth, with sculpin at sampling sites near the dams growing more rapidly, maturing earlier and attaining a larger size-at-age than sculpin at sites farther downstream or in natural systems. Differences in sculpin life history traits within rivers closely followed spatial patterns in food availability. We caution future researchers and managers to acknowledge the longitudinal gradients in abiotic and biotic conditions below dams early in experimental designs and monitoring programmes and how this may impact the measures of central tendency and statistical power when comparing rivers. Copyright © 2015 John Wiley & Sons, Ltd.