Influence of excesses of volatile elements on structure and composition of solution derived lead-free (Bi0.50Na0.50)1xBaxTiO3 thin films

The preparation of (Bi0.50Na0.50)1−xBaxTiO3 films requires a compositional/structural control, as they determine the functionality of these materials. We report a systematic compositional and structural analysis on (Bi0.50Na0.50)1−xBaxTiO3 films fabricated by chemical solution deposition. The effects of incorporating Na(I) and Bi(III) excesses are analyzed through the comparison of the compositional depth profiles of stoichiometric films (BNBT) and films containing excesses (BNBTxs). Heterogeneous compositional profiles with larger bismuth content close to the substrate and thicker film-substrate interfaces are observed in BNBTxs, unlike stoichiometric films, which show atomic concentrations that correspond to the nominal composition of the precursor solution. Excesses induce structural differences in depth, observing a shift of the region of coexistence of rhombohedral and tetragonal phases (morphotropic phase boundary) toward higher x values and the formation of thick film-substrate interfaces. In contrast, stoichiometric films have homogeneous compositional and structural profiles with the MPB placed close to that described for bulk ceramics.This work was financed by Spanish Project MAT2013-40489-P. D. Pérez-Mezcua acknowledges the financial support of the FPU Spanish program (AP2012-0639). A portion of this research was carried out at the Stanford Synchrotron Radiation Lightsource, a national user facility operated by Stanford University. D. Chateigner acknowledges the Conseil Régional de Basse Normandie for its partial financial of the four-circles X-ray diffractometer.Peer reviewe

Efecto del campo el?ctrico en la estructura cristalina de cer?micas submicroestructuradas DE (1-X)(Bi0.5Na0.5)TiO3- X BaTiO3 con composici?n pr?xima a la frontera morfotr?pica

--El sistema (1-x)(Bi0.5Na0.5)TiO3 - x BaTiO3 (BNBT100x) presenta una frontera morfotr?pica [1] (MPB) por lo que se presenta como posible material piezoel?ctrico "lead-free". Muy recientemente se han puesto de manifiesto peculiaridades estructurales de este sistema cerca de la MPB. La naturaleza y el rol de ordenamientos at?micos locales diferentes del orden global y la posibilidad de simetr?as inferiores a la rombo?drica son temas de actualidad. Exploramos aqu? el gran potencial de la difracci?n en alta resoluci?n de radiaci?n sincrotr?nica y el ajuste por Rietveld de los difractogramas de alta resoluci?n completos [2], que permite una mejor caracterizaci?n de las fases presentes que en los habituales an?lisis de grupos de picos aislados. Se determina el efecto del campo el?ctrico aplicado en cer?micas submicro- estructuradas [3] de composiciones BNBT4 y BNBT6 obtenidas a partir de precursores nanom?tricos preparados mediante autocombusti?n de sol-gel. Los experimentos de difracci?n se desarrollaron en el sincrotr?n de Stanford (USA) con radiaci?n de 12 keV. Para todas las muestras analizadas se consider? el difractograma completo para un recorrido del vector de dispersi?n Q entre 0 y 6.4?-1. En todos los casos investigados, se esclareci? la ocurrencia de las fases tetragonal P4mm, rombo?drica R3c y/o monocl?nica Cc. Se dan resultados cuantitativos de ocurrencia, concentraciones relativas, forma y tama?o de part?culas y orientaciones preferente

Adherence to treatment in allergic rhinitis using mobile technology. The MASK Study

Background: Mobile technology may help to better understand the adherence to treatment. MASK-rhinitis (Mobile Airways Sentinel NetworK for allergic rhinitis) is a patient-centred ICT system. A mobile phone app (the Allergy Diary) central to MASK is available in 22 countries. Objectives: To assess the adherence to treatment in allergic rhinitis patients using the Allergy Diary App. Methods: An observational cross-sectional study was carried out on all users who filled in the Allergy Diary from 1 January 2016 to 1 August 2017. Secondary adherence was assessed by using the modified Medication Possession Ratio (MPR) and the Proportion of days covered (PDC) approach. Results: A total of 12143 users were registered. A total of 6949 users reported at least one VAS data recording. Among them, 1887 users reported >= 7 VAS data. About 1195 subjects were included in the analysis of adherence. One hundred and thirty-six (11.28%) users were adherent (MPR >= 70% and PDC = 70% and PDC = 1.50) and 176 (14.60%) were switchers. On the other hand, 832 (69.05%) users were non-adherent to medications (MPR Conclusion and clinical relevance: Adherence to treatment is low. The relative efficacy of continuous vs on-demand treatment for allergic rhinitis symptoms is still a matter of debate. This study shows an approach for measuring retrospective adherence based on a mobile app. This also represents a novel approach for analysing medication-taking behaviour in a real-world setting.Peer reviewe

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe

Nrf2-interacting nutrients and COVID-19 : time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPAR gamma:Peroxisome proliferator-activated receptor, NF kappa B: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2 alpha:Elongation initiation factor 2 alpha). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT(1)R axis (AT(1)R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity

Morphotropic phase boundary in solution-derived (Bi0.5Na 0.5)1-x BaxTiO3 thin films: Part I crystalline structure and compositional depth profile

In this work, ferroelectric (Bi0.5Na0.5) 1-xBaxTiO3 thin films were fabricated by chemical solution deposition (CSD) with compositions x = 0.050-0.150. Stoichiometric thin films (hereinafter BNBT) and others containing 10 mol% excesses of Bi3+ and Na+ (BNBTxs) were spin coated onto Pt/TiO2/SiO2/(100)Si substrates and crystallized by rapid thermal processing at 650°C for 60 s in oxygen atmosphere. Crystalline structure is studied by X-ray diffraction using Cu anode (λCu = 1.5406) and synchrotron radiation (λ = 0.97354). Rietveld refinement showed the coexistence of rhombohedral/tetragonal phases in the BNBT films for x values close to those reported for (Bi0.5Na0.5) 1-xBaxTiO3 bulk ceramics. Different volume fractions of the rhombohedral/tetragonal phases are detected as a function of the Ba2+ content. An apparent shift of the position of the morphotropic phase boundary (MPB) is observed in the BNBTxs films. Here, the MPB region appears for nominal Ba2+ molar values of x ~ 0.10 and the experiments using a grazing-incidence synchrotron radiation indicate the existence of a crystalline phase with pyrochlore structure at the film surface. Rutherford backscattering experiments (RBS) revealed that the bismuth excess is not volatilized during the crystallization of the BNBTxs films which present inhomogeneous compositional depth profile and thick BixPt bottom interfaces. The MPB BNBT films with x ~ 0.055 have a homogeneous compositional depth profile without appreciable bottom interfaces. Scanning electron micrographs reveal less porosity and higher grain sizes in the stoichiometric films than in those with Bi3+ and Na+ excesses. © 2013 The American Ceramic Society.This work was financed by Spanish Project MAT2010-15365. D. Pérez-Mezcua acknowledges the financial support of the FPU Spanish program (AP2012-0639). Dr I. Bretos is grateful for the financial support of the Juan de la Cierva Spanish program. Dr R. Escobar Galindo acknowledges support through Ramon y Cajal programme (RyC2007-0026).Peer Reviewe

Photochemical solution processing of films of metastable phases for flexible devices: the β-Bi 2 O 3 polymorph

The potential of UV-light for the photochemical synthesis and stabilization of non-equilibrium crystalline phases in thin films is demonstrated for the β-Bi O polymorph. The pure β-Bi O phase is thermodynamically stable at high temperature (450-667 °C), which limits its applications in devices. Here, a tailored UV-absorbing bismuth(III)-N-methyldiethanolamine complex is selected as an ideal precursor for this phase, in order to induce under UV-light the formation of a -Bi-O-Bi- continuous network in the deposited layers and the further conversion into the β-Bi O polymorph at a temperature as low as 250 °C. The stabilization of the β-Bi O films is confirmed by their conductivity behavior and a thorough characterization of their crystal structure. This is also supported by their remarkable photocatalytic activity. Besides, this processing method has allowed us for the first time the preparation of β-Bi O films on flexible plastic substrates, which opens new opportunities for using these materials in potential applications not available until now (e.g., flexible photocatalytic reactors, self-cleaning surfaces or wearable antimicrobial fabrics). Therefore, photochemical solution deposition (PCSD) demonstrates to be not only an efficient approach for the low temperature processing of oxide films, but also an excellent alternative for the stabilization of metastable phases.This work was financed by Spanish Project MAT2013-40489-P and MAT2016-76851-R. The COST Action IC1208 also contributed to this study. I.B. acknowledges the financial support by Fundación General CSIC (Spanish ComFuturo Programme)

Do the Naica giant crystals deteriorate due to human sction?

Resumen del trabajo presentado al 25th international Congress on X-ray optic and microanalysis (ICXOM), celebrado en EE.UU. del 5 al 9 de agosto de 2019.The support given by CONACYT Project No. 183706 and by SSRL, ELETTRA, ESRF synchrotron facilities is acknowledged. Authors are thankful to Cia. Peñoles and Naica Mine for providing samples