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In the field of topological materials, the interaction between band topology and magnetism remains a current frontier for the advancement of new topological states and spintronic functionalities. Doping with rare-earth elements with large magnetic moments is a current approach to exploit the phenomenology of such interaction. However, dopant solubility into the main matrix plays a major role. In this sense, the present work is focused on elucidating how Eu incorporates into Bi2Te3lattice as a function of doping. This work reports a systematic investigation of the structural and electronic properties of bismuth telluride epitaxial layers doped with Eu. Bi2Te3films were grown by molecular beam epitaxy on (111) BaF2substrates with nominal Eu doping ranging from 0% up to 9%. X-ray diffraction analysis and scanning transmission electron microscopy reveal that Eu atoms enter substitutionally on Bi sites up to 4% of Eu doping. In contrast, the 9% Eu-doped sample contains epitaxially oriented nanoclusters of EuTe. X-ray photoelectron and absorption spectroscopies show that Eu atoms enter the Bi2Te3crystal matrix in the divalent Eu2+state for all Eu concentrations. Angle-resolved photoemission experiments indicate that the topological surface state is preserved in the presence of the local magnetic moments introduced by the Eu impurities.

Magnetic topological insulators are narrow-gap semiconductor materials that combine non-trivial band topology and magnetic order1. Unlike their nonmagnetic counterparts, magnetic topological insulators may have some of the surfaces gapped, which enables a number of exotic phenomena that have potential applications in spintronics1, such as the quantum anomalous Hall effect2and chiral Majorana fermions3. So far, magnetic topological insulators have only been created by means of doping nonmagnetic topological insulators with 3dtransition-metal elements; however, such an approach leads to strongly inhomogeneous magnetic4and electronic5properties of these materials, restricting the observation of important effects to very low temperatures2,3. An intrinsic magnetic topological insulator—a stoichiometric well ordered magnetic compound—could be an ideal solution to these problems, but no such material has been observed so far. Here we predict by ab initio calculations and further confirm using various experimental techniques the realization of an antiferromagnetic topological insulator in the layered van der Waals compound MnBi2Te4. The antiferromagnetic ordering  that MnBi2Te4shows makes it invariant with respect to the combination of the time-reversal and primitive-lattice translation symmetries, giving rise to a ℤ2topological classification; ℤ2= 1 for MnBi2Te4, confirming its topologically nontrivial nature. Our experiments indicate that the symmetry-breaking (0001) surface of MnBi2Te4exhibits a large bandgap in the topological surface state. We expect this property to eventually enable the observation of a number of fundamental phenomena, among them quantized magnetoelectric coupling6–8and axion electrodynamics9,10. Other exotic phenomena could become accessible at much higher temperatures than those reached so far, such as the quantum anomalous Hall effect2and chiral Majorana fermions3.

High-quality single crystals of MnBi2Te4are grown for the first time by slow cooling within a narrow range between the melting points of Bi2Te3(586 °C) and MnBi2Te4(600 °C). Single-crystal X-ray diffraction and electron microscopy reveal ubiquitous antisite defects in both cation sites and, possibly, Mn vacancies (Mn0.85(3)Bi2.10(3)Te4). Thermochemical studies complemented with high-temperature X-ray diffraction establish a limited high-temperature range of phase stability and metastability at room temperature. Nevertheless, the synthesis of MnBi2Te4can be scaled-up as powders can be obtained at subsolidus temperatures and quenched at room temperature. Bulk samples exhibit long-range antiferromagnetic ordering below 24 K. The Mn(II) out-of-plane magnetic state is confirmed by the magnetization, X-ray photoemission, X-ray absorption, and linear dichroism measurements. The compound shows a metallic type of resistivity in the range 4.5–300 K and is an n-type conductor that reaches a thermoelectric figure of merit up to ZT= 0.17. Angle-resolved photoemission experiments show a surface state forming a gapped Dirac cone, thus strengthening MnBi2Te4as a promising candidate for the intrinsic magnetic topological insulator, in accordance with theoretical predictions. The developed synthetic protocols enable further experimental studies of a crossover between magnetic ordering and nontrivial topology in bulk MnBi2Te4.

We performed a full mapping of the bulk electronic structure including the Fermi surface and Fermi-velocity distribution vF(kF) of tungsten. The 4D spectral function ρ(EB; k) in the entire bulk Brillouin zone and 6 eV binding-energy (EB) interval was acquired in ∼3 h thanks to a new multidimensional photoemission data-recording technique (combining full-field k-microscopy with time-of-flight parallel energy recording) and the high brilliance of the soft X-rays used. A direct comparison of bulk and surface spectral functions (taken at low photon energies) reveals a time-reversal-invariant surface state in a local bandgap in the (110)-projected bulk band structure. The surface state connects hole and electron pockets that would otherwise be separated by an indirect local bandgap. We confirmed its Dirac-like spin texture by spin-filtered momentum imaging. The measured 4D data array enables extraction of the 3D dispersion of all bands, all energy isosurfaces, electron velocities, hole or electron conductivity, effective mass and inner potential by simple algorithms without approximations. The high-Z bcc metals with large spin–orbit-induced bandgaps are discussed as candidates for topologically non-trivial surface states.

To investigate the biological origin of injectable unfractioned heparin available in Brazilian market by discussing the impact of the profile of commercial products and the changes in heparin monograph on the drug safety.

Investigar a origem das preparações de heparina, na forma farmacêutica injetável, disponíveis no mercado brasileiro, discutindo o impacto do perfil dos produtos comercializados e das alterações na monografia da heparina na segurança do fármaco.

We have demonstrated recently that the glycoinositolphospholipid (GIPL) molecule from the protozoan Trypanosoma cruziis a TLR4 agonist with proinflammatory effects. Here, we show that GIPL‐induced neutrophil recruitment into the peritoneal cavity is mediated by at least two pathways: one, where IL‐1β acts downstream of TNF‐α, and a second, which is IL‐1β‐ and TNFRI‐independent. Moreover, NKT cells participate in this proinflammatory cascade, as in GIPL‐treated CD1d−/−mice, TNF‐α and MIP‐2 levels are reduced significantly. As a consequence of this inflammatory response, spleen and lymph nodes of GIPL‐treated mice have an increase in the percentage of T and B cells expressing the CD69 activation marker. Cell‐transfer experiments demonstrate that T and B cell activation by GIPL is an indirect effect, which relies on the expression of TLR4 by other cell types. Moreover, although signaling through TNFRI contributes to the activation of B and γδ+T cells, it is not required for increasing CD69 expression on αβ+T lymphocytes. It is interesting that T cells are also functionally affected by GIPL treatment, as spleen cells from GIPL‐injected mice show enhanced production of IL‐4 following in vitro stimulation by anti‐CD3. Together, these results contribute to the understanding of the inflammatory properties of the GIPL molecule, pointing to its potential role as a parasite‐derived modulator of the immune response during T. cruziinfection.

Knowledge of population ancestry from genetic markers is essential, for example, to understand the history of human migration and to carry out admixture and association studies. Here we assess the genome ancestry of the Azorean population through analysis of six Alu polymorphic sites (TPA‐25, ACE, APO, B65, PV92, and D1) in 65 Azoreans and 30 Portuguese unrelated blood donors and compare data for the Y‐chromosome and mtDNA. Allele frequencies were calculated by direct counting. Statistical analysis was performed using Arlequin 2.0. Nei's genetic distance was calculated with DISPAN software, and trees were constructed by neighbor joining (NJ) using PHYLIP 3.63. The results show that all Alu insertions were polymorphic. APO is the closest to fixation. The less frequent insertions are PV92 and D1 in the Azores and Portugal, respectively. ACE and TPA‐25 show the highest values of heterozygosity in both populations. Allele frequencies are very similar to those obtained in European populations. These results are validated by the Y‐chromosome and mtDNA data, where the majority of the maternal and paternal lineages are European. Overall, these data are reflected in the phylogenetic tree, in which the Azoreans and the Portuguese branch with Catalans, Andalusians, Moroccans, and Algerians. We conclude that the population of the Azores shows no significant genetic differences from that of mainland Portugal and that it is an outbred population. Moreover, the data validate the use of Alu insertion polymorphisms to assess the origin and history of human populations. Am. J. Hum. Biol. 18:223–226, 2006. © 2006 Wiley‐Liss, Inc.

In order to obtain a better understanding of the genetic structure of the Azorean population, a specificity and spatial distribution analysis was performed, based on 2,454 different surnames present in the Azorean telephone directory (2002). We considered as specific surnames those with an absolute frequency ratio equal to or higher than 50%. The results revealed 51 specific surnames in the whole archipelago. The smallest island presents the only surname with 100% specificity (Pedras). In addition, São Miguel island, which contains 54% of the Azorean population, has the highest number of specific surnames (25 specific surnames). The spatial distribution analysis was used to detect genetic similarity between municipalities through the calculation of spatial autocorrelation (Moran's Icoefficient). Of 240 surnames included in the analysis, 113 showed statistically significant patterns. Five different patterns were obtained, of which the most relevant was isolation by distance and depression (41.6%). However, 43.4% had no defined pattern. The overall correlogram shows a majority of positive values for distances lower than 49 km and between 269–309 km, indicating high similarity between closer municipalities and between distant municipalities whose populations show historic and sociocultural affinities. In conclusion, our data are in agreement with the historical background of the Azorean population. Am. J. Hum. Biol. 17:634–645, 2005. © 2005 Wiley‐Liss, Inc.

Regional anesthesia has been increasingly used. Despite its low number of complications, they are associated with relevant morbidity. This study aims to evaluate the incidence of complications after neuraxial block and peripheral nerve block.