Mechanism Behind the Enhanced Ferromagnetic Contributions Upon Ru Substitution in CaMnO from X-Ray Absorption Spectroscopies.

We have studied the local structure and electronic and magnetic properties of hybrid improper ferroelectric CaMnO upon Ru substitution at the Mn site by a combination of atomic-selective X-ray absorption spectroscopies in the soft and hard X-ray energy regimes. Ru substitution enhances the macroscopic ferromagnetic contributions, whose origin is here elucidated. In particular, soft X-ray magnetic circular dichroism (XMCD) data indicate that the spin moments of Mn and Ru are aligned in opposite directions, with the effective magnetic moments of Ru being about 1 order of magnitude smaller than for Mn.

Interplay between local structure, vibrational and electronic properties on CuO under pressure.

The electronic and local structural properties of CuO under pressure have been investigated by means of X-ray absorption spectroscopy (XAS) at Cu K edge and ab initio calculations, up to 17 GPa. The crystal structure of CuO consists of Cu motifs within CuO square planar units and two elongated apical Cu-O bonds. The CuO square planar units are stable in the studied pressure range, with Cu-O distances that are approximately constant up to 5 GPa, and then decrease slightly up to 17 GPa.

Relation among Oxygen Stoichiometry, Structure, and Co Valence and Spin State in Single-Layer LaACoO (A = Ca, Sr) Perovskites.

We have investigated the role of oxygen stoichiometry and structural properties in the modulation of Co valence and spin state in single-layer LaACoO (A = Sr, Ca; 0 ≤ ≤ 1) perovskites as well as the interplay between their local structural properties and the magnetic and charge-ordering phenomena. We show the results of high angular resolution powder X-ray diffraction and Co -edge X-ray absorption and emission spectroscopy experiments on polycrystalline and single-crystal samples. The different doping-induced changes in the Co valence and spin state by Ca (or Sr) substitution can be understood in terms of the evolving oxygen stoichiometry.

RHBDD2 overexpression promotes a chemoresistant and invasive phenotype to rectal cancer tumors via modulating UPR and focal adhesion genes.

The current standard of care for locally advanced rectal cancer (RC) is neoadjuvant radio-chemotherapy (NRC) with 5-fluorouracil (5Fu) as the main drug, followed by surgery and adjuvant chemotherapy. While a group of patients will achieve a pathological complete response, a significant percentage will not respond to the treatment. The Unfolding Protein Response (UPR) pathway is generally activated in tumors and results in resistance to radio-chemotherapy.

Phase stability and electronic structure of iridium metal at the megabar range.

The 5d transition metals have attracted specific interest for high-pressure studies due to their extraordinary stability and intriguing electronic properties. In particular, iridium metal has been proposed to exhibit a recently discovered pressure-induced electronic transition, the so-called core-level crossing transition at the lowest pressure among all the 5d transition metals. Here, we report an experimental structural characterization of iridium by x-ray probes sensitive to both long- and short-range order in matter.

Stability and nature of the volume collapse of ε-FeO under extreme conditions.

Iron oxides are among the major constituents of the deep Earth's interior. Among them, the epsilon phase of FeO is one of the less studied polymorphs and there is a lack of information about its structural, electronic and magnetic transformations at extreme conditions. Here we report the precise determination of its equation of state and a deep analysis of the evolution of the polyhedral units under compression, thanks to the agreement between our experiments and ab-initio simulations.

Structural, Magnetic, and Electronic Properties of CaBaCoM O (M = Fe, Zn).

The effect of substituting iron and zinc for cobalt in CaBaCoO was investigated using neutron diffraction and X-ray absorption spectroscopy techniques. The orthorhombic distortion present in the parent compound CaBaCoO decreases with increasing the content of either Fe or Zn. The samples CaBaCoZnO and CaBaCoFe O with x ≥ 1.

2D/3D Microanalysis by Energy Dispersive X-ray Absorption Spectroscopy Tomography.

X-ray spectroscopic techniques have proven to be particularly useful in elucidating the molecular and electronic structural information of chemically heterogeneous and complex micro- and nano-structured materials. However, spatially resolved chemical characterization at the micrometre scale remains a challenge. Here, we report the novel hyperspectral technique of micro Energy Dispersive X-ray Absorption Spectroscopy (μED-XAS) tomography which can resolve in both 2D and 3D the spatial distribution of chemical species through the reconstruction of XANES spectra.

[Recommendations for the management of pancreatic cancer type adenocarcinoma: A consensus statement reached during the 2015 Latin American Symposium on Gastroenterological Oncology].

Pancreatic cancer is a malignancy of great impact in developed countries and is having an increasing impact in Latin America. Incidence and mortality rates are similar for this cancer. This is an important reason to offer to the patients the best treatments available.

Performance and characteristics of a high pressure, high temperature capillary cell with facile construction for operando x-ray absorption spectroscopy.

We demonstrate the use of commercially available fused silica capillary and fittings to construct a cell for operando X-ray absorption spectroscopy (XAS) for the study of heterogeneously catalyzed reactions under high pressure (up to 200 bars) and high temperature (up to 280 °C) conditions. As the first demonstration, the cell was used for CO2 hydrogenation reaction to examine the state of copper in a conventional Cu/ZnO/Al2O3 methanol synthesis catalyst. The active copper component of the catalyst was shown to remain in the metallic state under supercritical reaction conditions, at 200 bars and up to 260 °C.

Stability of the cationic oxidation states in Pr(0.50)Sr(0.50)CoO₃ across the magnetostructural transition by X-ray absorption spectroscopy.

The possible hybridization between Pr 4f and O 2p states in Pr(0.50)Sr(0.50)CoO3 at low temperatures was investigated by different techniques.

Evolution of magnetoelectric properties of Sc-diluted TbMnO3.

The magnetoelectric properties of the TbMn(1-x)Sc(x)O3 series have been studied at low temperatures by means of heat capacity, magnetic measurements and impedance spectroscopy. TbMnO3 exhibits as expected three transitions upon lowering the temperature corresponding to the magnetic ordering of the two sublattices (Mn and Tb) and the ferroelectric transition. Ferroelectricity disappears with Sc dilution for x > 0.

Enhancement of ferromagnetic correlations on multiferroic TbMnO₃ by replacing Mn with Co.

The structural, electronic and magnetic properties of TbMn(1-x)Co(x)O(3) (0.1 ≤ x ≤ 0.9) compounds are reported.

Structural properties of Pb2MnW(1-x)Re(x)O6 double perovskites.

Pb2MnW(1-x)Re(x)O6 samples have been synthesized and their structure determined by powder x-ray diffraction. These samples undergo a first order structural phase transition between 413 and 445 K depending on the composition. Above this temperature, the samples are cubic.

The transition from ferromagnet to cluster-glass in La(1-x)Tb(x)Mn1/2Sc1/2O3.

We report the structural and magnetic properties of the La(1-x)Tb(x)Mn(1/2)Sc(1/2)O(3) series. LaMn(1/2)Sc(1/2)O(3) shows a long range ferromagnetic ordering in agreement with a fully polarized Mn-sublattice. The substitution of La with Tb produces structural changes which affect the magnetic properties.

Origin of the pre-peak features in the oxygen K-edge x-ray absorption spectra of LaFeO₃ and LaMnO₃ studied by Ga substitution of the transition metal ion.

We report on experimental oxygen K-edge x-ray absorption near edge structure (XANES) spectra of the LaFe(1 - x)Ga(x)O(3) and LaMn(1 - x)Ga(x)O(3) series. Transition metal substitution by the 3d full shell Ga atom is mainly reflected in a systematic decrease of the pre-edge structures in the XANES spectra of the two series. This result shows that the associated states originate from the hybridization of oxygen 2p and unoccupied Fe (or Mn) 3d states.

A new type of antiferrodistortive structure in a double perovskite with Pb.

We have found a new structural transition in Pb(2)MnReO(6) at 410 K. Above this temperature, Pb(2)MnReO(6) is cubic with disordered and dynamic atomic displacements manifested in the large thermal parameters of Pb and O atoms. Below 410 K, the antiferrodistortive shift of 2/3 of Pb(2+) cations away from the high-symmetry cubic site produces a new type of monoclinic cell.

On the correlation between the X-ray absorption chemical shift and the formal valence state in mixed-valence manganites.

Here the correlation between the chemical shift in X-ray absorption spectroscopy, the geometrical structure and the formal valence state of the Mn atom in mixed-valence manganites are discussed. It is shown that this empirical correlation can be reliably used to determine the formal valence of Mn, using either X-ray absorption spectroscopy or resonant X-ray scattering techniques. The difficulties in obtaining a reliable comparison between experimental XANES spectra and theoretical simulations on an absolute energy scale are revealed.

Reexamination of the temperature dependences of resonant reflections in highly stoichiometric magnetite.

We have studied the temperature dependences of the so-called charge and orbital ordering reflections in the neighborhood of the Verwey transition by means of resonant x-ray scattering at the Fe K and L edges on a high purity single crystal of magnetite. Contrary to recently published results [J. E.

[Retrorectal cystic hamartoma (tailgut cyst): radiologic and pathologic findings].

Cystic hamartoma is a rare congenital lesion that presents as a presacral mass. It arises from remnants of the embryonic postanal gut. It is more common in women and usually presents in middle age.

[Color Doppler echography study of ocular blood flow velocity in patients with proliferative diabetic retinopathy after performance of retinal pan-photocoagulation: 2 years' follow-up].

Purpose: Color Doppler imaging allows for simultaneous two-dimensional anatomical imaging and Doppler measurement of blood flow velocity. Because hemodynamic changes have been seen in diabetic patients after photocoagulation by other techniques, the authors compared 25 eyes with proliferative diabetic retinopathy before, 6 months, 1 year, and 2 years after panretinal photocoagulation with a matched control group of 30 healthy volunteers.

Methods: The ophthalmic artery, short posterior ciliary artery, central retinal vessels and vortex veins of all patients were examined, and the systolic, diastolic and mean arterial velocities were measured.

Color Doppler image of central retinal artery of eyes with an intraconal mass.

Purpose: Retinal ischemia secondary to hypoperfusion of the central retinal artery is recognized as one factor that may contribute to the development of loss of vision in eyes with intraorbital tumors. We study intraorbital tumors which produce motility disturbances and visual problems by color Doppler imaging to evaluate this factor.

Methods: We examined the central retinal artery velocities of 3 patients with disc edema caused by intraconal masses (2 cavernous hemangiomas and 1 presumed optic nerve glioma) via color Doppler imaging.