XAFS atomistic insight of the oxygen gettering in Ti/HfO2 based OxRRAM

Hafnia-based resistive memories technology has come to maturation and acceded to the market of nonvolatile memories. Nevertheless, the physical mechanisms involved in resistive switching are not yet fully understood and the numerous ab initio simulations studies have few many atomic-scale experimental counterparts. In this study we investigate the oxygen migration mechanism from an amorphous HfO2 layer to the Ti cap layer at a local scale before and after a thermal treatment. X-ray absorption spectroscopy at the Ti K edge and Hf L(III )edge has been performed on samples as-deposited and annealed in Ar at 400 degrees C to mimic the back-end-of-line thermal budget (BEOL) of CMOS technology. The short-range Ti and Hf environments have been determined, showing that annealing promotes the migration of O from HfO2 to Ti, the amount of which is quantified. This provokes an expansion and an increase of atomic disorder in the Ti lattice. The nature of the oxygen gettering mechanism by the Ti metal is understood by comparing samples with increasing Ti-capping thickness. We show that the Ti getter effect has to be activated by thermal treatment and that the O diffusion takes place in a region of a few nanometers close to the Ti/HfO2 interface. Therefore, the thermal budget history and the Ti cap-layer thickness determine the oxygen vacancy content in the HfO2 layer, which in turn controls the electrical properties, especially the forming operation

Platelet activation is associated with myocardial infarction in patients with pneumonia

BACKGROUND: Troponins may be elevated in patients with pneumonia, but associations with myocardial infarction (MI) and with platelet activation are still undefined.OBJECTIVES: The aim of this study was to investigate the relationship between troponin elevation and in vivo markers of platelet activation in the early phase of hospitalization of patients affected by community-acquired pneumonia.METHODS: A total of 278 consecutive patients hospitalized for community-acquired pneumonia, who were followed up until discharge, were included. At admission, platelet activation markers such as plasma soluble P-selectin, soluble CD40 ligand, and serum thromboxane B2 (TxB2) were measured. Serum high-sensitivity cardiac troponin T levels and electrocardiograms were obtained every 12 and 24 h, respectively.RESULTS: Among 144 patients with elevated high-sensitivity cardiac troponin T, 31 had signs of MI and 113 did not. Baseline plasma levels of soluble P-selectin and soluble CD40 ligand and serum TxB2 were significantly higher in patients who developed signs of MI. Logistic regression analysis showed plasma soluble CD40 ligand (p < 0.001) and soluble P-selectin (p < 0.001), serum TxB2 (p = 0.030), mean platelet volume (p = 0.037), Pneumonia Severity Index score (p = 0.030), and ejection fraction (p = 0.001) to be independent predictors of MI. There were no significant differences in MI rate between the 123 patients (45%) taking aspirin (100 mg/day) and those who were not aspirin treated (12% vs. 10%; p = 0.649). Aspirin-treated patients with MIs had higher serum TxB2 compared with those without MIs (p = 0.005).CONCLUSIONS: MI is an early complication of pneumonia and is associated with in vivo platelet activation and serum TxB2 overproduction; aspirin 100 mg/day seems insufficient to inhibit thromboxane biosynthesis. (MACCE in Hospitalized Patients With Community-acquired Pneumonia; NCT01773863)

Socioeconomic Predictors of the Employment of Migrant Care Workers by Italian Families Assisting Older Alzheimer's Disease Patients: Evidence from the Up-Tech Study

Background: The availability of family caregivers of older people is decreasing in Italy as the number of migrant care workers (MCWs) hired by families increases. There is little evidence on the influence of socioeconomic factors in the employment of MCWs. Method: We analyzed baseline data from 438 older people with moderate Alzheimer's disease (AD), and their family caregivers enrolled in the Up-Tech trial. We used bivariate analysis and multilevel regressions to investigate the association between independent variables - education, social class, and the availability of a care allowance - and three outcomes - employment of a MCW, hours of care provided by the primary family caregiver, and by the family network (primary and other family caregivers). Results: The availability of a care allowance and the educational level were independently associated with employing MCWs. A significant interaction between education and care allowance was found, suggesting that more educated families are more likely to spend the care allowance to hire a MCW. Discussion: Socioeconomic inequalities negatively influenced access both to private care and to care allowance, leading disadvantaged families to directly provide more assistance to AD patients. Care allowance entitlement needs to be reformed in Italy and in countries with similar long-term care and migration systems. � 2015 The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved

Magnetic ripple domain structure in FeGa/MgO thin films

The magnetic domain structure is studied in epitaxial /MgO(0 0 1) films with 0 < x < 30 and thicknesses below 60 nm by magnetic force microscopy. For low gallium content, domains with the magnetization lying in the film plane and domain walls separating micrometric areas are observed. Above x ≈ 20, the magnetic contrast shows a fine corrugation, ranging from 300 to 900 nm, suggesting a ripple substructure with a periodic oscillation of the magnetization. We discuss the presence of a random magnetic anisotropy contribution, that superimposed to the cubic coherent anisotropy, is able to break the uniform orientation of the magnetization. The origin of that random anisotropy is attributed to several factors: coexistence of crystal phases in the films, inhomogeneous distribution of both internal strain and Ga–Ga next nearest neighbor pairs and interface magnetic anisotropy due to the Fe–O bond

EXAFS Investigation of the Ni2+ Environment in Heavy-Meta1 Fluoride Glasses

The nickel local structure of Ni doped heavy metal fluoride glasses of the type ZrF4-BaF2-LaF3-NaF-(BaCl2) as a function of the chlorine content has been determined by means of x-ray absorption spectroscopy. Nickel ion is surrounded by six halides in octahedral configuration in all the samples studied. At low chlorine content nickel is coordinated only by fluorine, at intermediate concentrations Ni coordinate three fluorine and three chlorine presumably in trigonal symmetry and at high Cl concentrations by only six chlorine. Our results correlates with the optical absorption spectra of Ni2+ which shows that the 1E band characteristic of Ni2+ coordinated by six fluorine atoms changes in shape and energy position with the Cl content

Hydrogen Influence on XAS Spectra of Transition Metal Complexes in Aqueous Solution

In this paper we present a direct evidence o f the influence of hydrogen atoms on the XANES spectra of transition metal complexes in aqueous solution. The metal K-edges of Ni2+ and Co2+ are analyzed by multiple scattering theory using different clusters around the absorber and different final state potentials. On this basis the presence of hydrogen atoms has been found to be necessary to reproduce the width and the relative amplitude ratio of the experimental features

Atypical disseminated leishmaniasis resembling post-kala-azar dermal leishmaniasis in an HIV-infected patient

Post-kala-azar dermal leishmaniasis (PKDL) is very uncommon among HIV-positive patients, and very few cases have so far been documented. A case of atypical disseminated leishmaniasis resembling PKDL in an HIV-positive patient successfully treated with N-methylglucamine antimoniate is reported. The polymerase chain reaction performed on the skin lesions was positive for Leishmania infantum

SEXAFS Study of the GaAs/InP Interface

Extended X-Ray Absorption Fine Structure measurements have been performed at the Ga and As K-edge of a nominal 3 ML GaAs grown by Molecular Beam Epitaxy on a InP(100) substrate deoxidized in As amiosphere. We exploited the in-plane linear polarization of the synchrotron radiation measuring SEXAFS spectra taken with the polarization vector parallel and pependicular to the growth direction. By comparing the ratio of the coordination numbers of the pairs As-Ga, As-In, Ga-As, taken at the two different angles of the polarization vector, a quantitative model of the interface is obtained. Two well defined layers form on the InP substrate giving rise to the following sample structure : 3 ML GaAs/3 ML InAs/InP. This rules out the formation of InGaAs or InGaAsP layers at the interface

Multiwavelength anomalous diffraction and diffraction anomalous fine structure to study composition and strain of semiconductor nanostructures

The aim of this paper is to illustrate the use of Multi-Wavelength Anomalous Diffraction (MAD) and Diffraction Anomalous Fine Structure (DAFS) spectroscopy for the study of structural properties of semiconductor nanostructures. We give a brief introduction on the basic principles of these techniques providing a detailed bibliography. Then we focus on the data reduction and analysis and we give specific examples of their application on three different kinds of semiconductor nanostructures: Ge/Si nanoislands, AlN capped GaN/AlN Quantum Dots and AlGaN/AlN Nanowires. We show that the combination of MAD and DAFS is a very powerful tool to solve the structural problem of these materials of high technological impact. In particular, the effects of composition and strain on diffraction are disentangled and composition can be determined in a reliable way, even at the interface between nanostructure and substrate. We show the great possibilities of this method and give the reader the basic tools to undertake its use