754 research outputs found
Structural Properties and Relative Stability of (Meta)Stable Ordered, Partially-ordered and Disordered Al-Li Alloy Phases
We resolve issues that have plagued reliable prediction of relative phase
stability for solid-solutions and compounds. Due to its commercially important
phase diagram, we showcase Al-Li system because historically density-functional
theory (DFT) results show large scatter and limited success in predicting the
structural properties and stability of solid-solutions relative to ordered
compounds. Using recent advances in an optimal basis-set representation of the
topology of electronic charge density (and, hence, atomic size), we present DFT
results that agree reasonably well with all known experimental data for the
structural properties and formation energies of ordered, off-stoichiometric
partially-ordered and disordered alloys, opening the way for reliable study in
complex alloys.Comment: 7 pages, 2 figures, 2 Table
Anodic dissolution of metals in oxide-free cryolite melts
The anodic behavior of metals in molten cryolite-alumina melts has been investigated mostly for use as inert anodes for the Hall-HĂ©roult process. In the present work, gold, platinum, palladium, copper, tungsten, nickel, cobalt and iron metal electrodes were anodically polarized in an oxide-free cryolite melt (11%wt. excess AlF3 ; 5%wt. CaF2) at 1273 K. The aim of the experiments was to characterize the oxidation reactions of the metals occurring without the effect of oxygen-containing dissolved species. The anodic dissolution of each metal was demonstrated, and electrochemical reactions were assigned using reversible potential calculation. The relative stability of metals as well as the possibility of generating pure fluorine is discussed
Efeito de diferentes concentrações de ferro na cultura in vitro de Coqueiro Gigante do Brasil praia do Forte.
Estabelecimento de protocolo de cultura in vitro de embriões zigóticos do coqueiro Anão vermelho da Malásia.
Is higher education more important for firms than research? Disentangling university spillovers
The paper is the first attempt to integrate microdata on universities and firms across most European countries in order to disentangle the impact of knowledge spillovers from human capital (graduates) and intellectual capital (codified research output) on the performance of firms. Data cover all Higher Education Institutions (HEIs) registered in the official European Tertiary Education Register (ETER). Data on performance of firms are from ORBIS and refer to change in the 2011–2015 period in turnover, total assets, intangible assets, and employment. Firms are georeferred and the spillovers from all HEIs located at a given distance are summed and integrated. The findings suggest that, among knowledge spillovers, the creation of human capital via education of students has a larger impact than the circulation of research knowledge. Moreover, the two factors seem to be complements rather than substitutes. Spatial proximity is important for embodied knowledge spillovers (i.e. educated people), while for codified and disembodied spillovers (citations to publications) the spatial dimension is less relevant. The findings have important managerial and policy-making consequences
High-fidelity simulations of CdTe vapor deposition from a new bond-order potential-based molecular dynamics method
CdTe has been a special semiconductor for constructing the lowest-cost solar
cells and the CdTe-based Cd1-xZnxTe alloy has been the leading semiconductor
for radiation detection applications. The performance currently achieved for
the materials, however, is still far below the theoretical expectations. This
is because the property-limiting nanoscale defects that are easily formed
during the growth of CdTe crystals are difficult to explore in experiments.
Here we demonstrate the capability of a bond order potential-based molecular
dynamics method for predicting the crystalline growth of CdTe films during
vapor deposition simulations. Such a method may begin to enable defects
generated during vapor deposition of CdTe crystals to be accurately explored
Epitaxial Zn(x)Fe(3-x)O(4) Thin Films: A Spintronic Material with Tunable Electrical and Magnetic Properties
The ferrimagnetic spinel oxide Zn(x)Fe(3-x)O(4) combines high Curie
temperature and spin polarization with tunable electrical and magnetic
properties, making it a promising functional material for spintronic devices.
We have grown epitaxial thin films with 0<=x<=0.9 on MgO(001) substrates with
excellent structural properties both in pure Ar atmosphere and an Ar/O2 mixture
by laser molecular beam epitaxy. We find that the electrical conductivity and
the saturation magnetization can be tuned over a wide range during growth. Our
extensive characterization of the films provides a clear picture of the
underlying physics of this spinel ferrimagnet with antiparallel Fe moments on
the A and B sublattice: (i) Zn substitution removes both Fe3+ moments from the
A sublattice and itinerant charge carriers from the B sublattice, (ii) growth
in finite oxygen partial pressure generates Fe vacancies on the B sublattice
also removing itinerant charge carriers, and (iii) application of both Zn
substitution and excess oxygen results in a compensation effect as Zn
substitution partially removes the Fe vacancies. A decrease (increase) of
charge carrier density results in a weakening (strengthening) of double
exchange and thereby a decrease (increase) of conductivity and the saturation
magnetization. This scenario is confirmed by the observation that the
saturation magnetization scales with the longitudinal conductivity. The
combination of tailored films with semiconductor materials such as ZnO in
multi-functional heterostructures seems to be particularly appealing.Comment: 13 pages, 8 figures, Hall effect data removed, anti-phase boundary
discussion added, accepted for publication in PRB79 (2009
Natural Killer Cells Limit Cardiac Inflammation and Fibrosis by Halting Eosinophil Infiltration
Myocarditis is a leading cause of sudden cardiac failure in young adults. Natural killer (NK) cells, a subset of the innate lymphoid cell compartment, are protective in viral myocarditis. Herein, we demonstrated that these protective qualities extend to suppressing autoimmune inflammation. Experimental autoimmune myocarditis (EAM) was initiated in BALB/c mice by immunization with myocarditogenic peptide. During EAM, activated cardiac NK cells secreted interferon γ, perforin, and granzyme B, and expressed CD69, tumor necrosis factor–related apoptosis-inducing ligand treatment, and CD27 on their cell surfaces. The depletion of NK cells during EAM with anti-asialo GM1 antibody significantly increased myocarditis severity, and was accompanied by elevated fibrosis and a 10-fold increase in the percentage of cardiac-infiltrating eosinophils. The resultant influx of eosinophils to the heart was directly responsible for the increased disease severity in the absence of NK cells, because treatment with polyclonal antibody asialogangloside GM-1 did not augment myocarditis severity in eosinophil-deficient ΔdoubleGATA1 mice. We demonstrate that NK cells limit eosinophilic infiltration both indirectly, through altering eosinophil-related chemokine production by cardiac fibroblasts, and directly, by inducing eosinophil apoptosis in vitro. Altogether, we define a new pathway of eosinophilic regulation through interactions with NK cells
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