Structural and magnetic properties of an InGaAs/Fe3_3Si superlattice in cylindrical geometry

The structure and the magnetic properties of an InGaAs/Fe3Si superlattice in a cylindrical geometry are investigated by electron microscopy techniques, x-ray diffraction and magnetometry. To form a radial superlattice, a pseudomorphic InGaAs/Fe3As bilayer has been released from its substrate self-forming into a rolled-up microtube. Oxide-free interfaces as well as areas of crystalline bonding are observed and an overall lattice mismatch between succeeding layers is determined. The cylindrical symmetry of the final radial superlattice shows a significant effect on the magnetization behavior of the rolled-up layers

High-frequency oscillation and tracheal gas insufflation in patients with severe acute respiratory distress syndrome and traumatic brain injury: an interventional physiological study

In acute respiratory distress syndrome (ARDS), combined high-frequency oscillation (HFO) and tracheal gas insufflation (TGI) improves gas exchange compared with conventional mechanical ventilation (CMV). We evaluated the effect of HFO-TGI on PaO2/fractional inspired O2 (FiO2) and PaCO2, systemic hemodynamics, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) in patients with traumatic brain injury (TBI) and concurrent severe ARDS

Direct strain and elastic energy evaluation in rolled-up semiconductor tubes by x-ray micro-diffraction

We depict the use of x-ray diffraction as a tool to directly probe the strain status in rolled-up semiconductor tubes. By employing continuum elasticity theory and a simple model we are able to simulate quantitatively the strain relaxation in perfect crystalline III-V semiconductor bi- and multilayers as well as in rolled-up layers with dislocations. The reduction in the local elastic energy is evaluated for each case. Limitations of the technique and theoretical model are discussed in detail.Comment: 32 pages (single column), 9 figures, 39 reference

Narrativas como recurso para la Enseñanza de las Ciencias : un caso con la historia de la tabla periódica

En este trabajo analizamos el aprendizaje de alumnos de 8vo año de enseñanza básica, en Brasil, delante de aspectos de la historia de la Química, al utilizar el enfoque narrativo y descriptivo en aulas. El análisis de los textos producidos por los estudiantes mostró variaciones significativas en el aprendizaje de un mismo contenido cuando el profesor utiliza géneros discursivos distintos. Cuando el abordaje del contenido es apenas descriptivo los alumnos enfatizan la definición de conceptos y no demuestran interés por lo aprendido. Las redacciones de los alumnos expuestos a aulas narrativas, demuestran la riqueza de detalles aprendidos, la valorización del orden cronológico de los descubrimientos y una admiración por los científicos participantes de la construcción de la tabla periódica

Narrativas como recurso para la Enseñanza de las Ciencias : un caso con la historia de la tabla periódica

En este trabajo analizamos el aprendizaje de alumnos de 8vo año de enseñanza básica, en Brasil, delante de aspectos de la historia de la Química, al utilizar el enfoque narrativo y descriptivo en aulas. El análisis de los textos producidos por los estudiantes mostró variaciones significativas en el aprendizaje de un mismo contenido cuando el profesor utiliza géneros discursivos distintos. Cuando el abordaje del contenido es apenas descriptivo los alumnos enfatizan la definición de conceptos y no demuestran interés por lo aprendido. Las redacciones de los alumnos expuestos a aulas narrativas, demuestran la riqueza de detalles aprendidos, la valorización del orden cronológico de los descubrimientos y una admiración por los científicos participantes de la construcción de la tabla periódica

Magnetic structure and critical behavior of GdRhIn5_{5}: resonant x-ray diffraction and renormalization group analysis

The magnetic structure and fluctuations of tetragonal GdRhIn5 were studied by resonant x-ray diffraction at the Gd LII and LIII edges, followed by a renormalization group analysis for this and other related Gd-based compounds, namely Gd2IrIn8 and GdIn3. These compounds are spin-only analogs of the isostructural Ce-based heavy-fermion superconductors. The ground state of GdRhIn5 shows a commensurate antiferromagnetic spin structure with propagation vector tau = (0,1/2, 1/2), corresponding to a parallel spin alignment along the a-direction and antiparallel alignment along b and c. A comparison between this magnetic structure and those of other members of the Rm(Co,Rh,Ir)n In3m+2n family (R =rare earth, n = 0, 1; m = 1, 2) indicates that, in general, tau is determined by a competition between first-(J1) and second-neighbor(J2) antiferromagnetic (AFM) interactions. While a large J1 /J2 ratio favors an antiparallel alignment along the three directions (the so-called G-AFM structure), a smaller ratio favors the magnetic structure of GdRhIn5 (C-AFM). In particular, it is inferred that the heavy-fermion superconductor CeRhIn5 is in a frontier between these two ground states, which may explain its non-collinear spiral magnetic structure. The critical behavior of GdRhIn5 close to the paramagnetic transition at TN = 39 K was also studied in detail. A typical second-order transition with the ordered magnetization critical parameter beta = 0.35 was experimentally found, and theoretically investigated by means of a renormalization group analysis.Comment: 22 pages, 4 figure

N-terminal pro-B-type natriuretic peptide by itself predicts death and cardiovascular events in high-risk patients with type 2 diabetes

Background: NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide) improves the discriminatory ability of risk‐prediction models in type 2 diabetes mellitus (T2DM) but is not yet used in clinical practice. We assessed the discriminatory strength of NT‐proBNP by itself for death and cardiovascular events in high‐risk patients with T2DM. Methods and Results: Cox proportional hazards were used to create a base model formed by 20 variables. The discriminatory ability of the base model was compared with that of NT‐proBNP alone and with NT‐proBNP added, using C‐statistics. We studied 5509 patients (with complete data) of 8561 patients with T2DM and cardiovascular and/or chronic kidney disease who were enrolled in the ALTITUDE (Aliskiren in Type 2 Diabetes Using Cardiorenal Endpoints) trial. During a median 2.6‐year follow‐up period, 469 patients died and 768 had a cardiovascular composite outcome (cardiovascular death, resuscitated cardiac arrest, nonfatal myocardial infarction, stroke, or heart failure hospitalization). NT‐proBNP alone was as discriminatory as the base model for predicting death (C‐statistic, 0.745 versus 0.744, P=0.95) and the cardiovascular composite outcome (C‐statistic, 0.723 versus 0.731, P=0.37). When NT‐proBNP was added, it increased the predictive ability of the base model for death (C‐statistic, 0.779 versus 0.744, P<0.001) and for cardiovascular composite outcome (C‐statistic, 0.763 versus 0.731, P<0.001). Conclusions: In high‐risk patients with T2DM, NT‐proBNP by itself demonstrated discriminatory ability similar to a multivariable model in predicting both death and cardiovascular events and should be considered for risk stratification

Rolled-up tubes and cantilevers by releasing SrRuO₃-Pr₀̣₇Ca₀̣₃MnO₃ nanomembranes

Three-dimensional micro-objects are fabricated by the controlled release of inherently strained SrRuO3/ Pr0.7Ca0.3MnO3/SrRuO3 nanometer-sized trilayers from SrTiO3(001) substrates. Freestanding cantilevers and rolled-up microtubes with a diameter of 6 to 8 μm are demonstrated. The etching behavior of the SrRuO3 film is investigated, and a selectivity of 1:9,100 with respect to the SrTiO3 substrate is found. The initial and final strain states of the rolled-up oxide layers are studied by X-ray diffraction on an ensemble of tubes. Relaxation of the sandwiched Pr0.7Ca0.3MnO3 layer towards its bulk lattice parameter is observed as the major driving force for the roll-up of the trilayers. Finally, μ-diffraction experiments reveal that a single object can represent the ensemble proving a good homogeneity of the rolled-up tubes. PACS: 81.07.-b; 68.60.-p; 68.37.Lp; 81.16.Dn