Ceramics with eutectic microstructure in the ZrO2–PrOx system

Praseodymium oxides present redox properties analogous to those of Ce‐based systems and have been proposed for catalytic applications in combination with CeO2, ZrO2, or both. However, uncertainties remain concerning the nature and redox behavior of Pr‐rich mixtures, especially with ZrO2. Here we study the eutectic composites of the ZrO2–PrOx system, focusing on the sensitivity of their microstructure, phase symmetry, and composition to variations of the processing atmosphere from oxidizing to reducing. Mixed oxides have been produced by a laser‐assisted directional solidification technique in O2, air, N2, or 5%H2(Ar) environment, and the resulting materials have been analyzed by scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Raman spectroscopy, and magnetic susceptibility. In air, N2, or 5%H2(Ar) atmosphere, a lamellar, eutectic‐like microstructure forms, the major phase being the one with less Pr content. Both the Pr concentration in each phase as the PrOx molar percentage of the eutectic composites decrease as the atmosphere becomes more reducing. Both eutectic phases are fluorite‐like when processing in air, whereas in N2 or 5%H2(Ar), the phase with high Pr content is of the A‐R2O3 type, and the phase with low Pr content can be described as a fluorite phase containing C‐R2O3‐like short‐range‐ordered regions. The results obtained for samples processed in O2 suggest that for high enough pO2 no eutectic forms, in analogy with the ZrO2–CeO2 system. The evolution of the phase composition and symmetry is discussed in terms of the limited stability of the phases found in the ZrO2–Pr2O3 system, namely, A‐ or C‐R2O3‐like, beyond a certain Pr oxidation degree and oxygen content

Fabricación mediante fusión con laser y caracterización de compuestos de alúmina monocristalina

El objetivo del presente trabajo ha sido la fabricación de fibras monocristalinas de alúmina pura y dopada con metales de transición mediante fusión zonal asistida con láser. Se determinaron las condiciones óptimas para la obtención de fibras monocristalinas. Se llevó a cabo el estudio microestructural y mecánico de las muestras obtenidas

Quantification of the resonant energy transfer processes in Er3+/Yb3+ co-doped Ca3Al2Si3O12 glasses

The resonant cross relaxation processes between Yb3+ and Er3+ ions in calcium alumino-silicate glasses have been quantified under selective Er3+ excitation. The infrared emission spectra, measured under steady state conditions (CW excitation to the 4I9/2 erbium level), have allowed to obtain an experimental relationship linking the transfer (Yb3+ → Er3+) and back transfer (Er3+ → Yb3+) parameters. These measurements combined with the dynamics of the main emitting levels, measured under pulsed excitation to the 2H11/2 erbium level, have allowed the fully quantification of the energy transfer parameters. The obtained values, C25=5.5×10−18cm3s−1 (Yb3+ → Er3+), C52=1.5×10−18cm3s−1 (Er3+ → Yb3+) and C27=7.6×10−18cm3s−1 (up-conversion mechanism, estimated from the Judd-Ofelt analysis previously reported), can be used to predict the temporal evolution of the main luminescent emission band

Determinación de plata en muestras biológicas mediante técnicas de espectrometría atómica

La plata, debido a sus propiedades biocidas, está siendo utilizada, fundamentalmente en forma de nanopartículas metálicas, en distintos campos, tales como en la industria textil, medicina electrodomésticos, así como en la purificación de aguas. Debido a que las nanopartículas de plata pueden ser potencialmente tóxicas para distintos organismos, es necesario estudiar los procesos de absorción, distribución, metabolismo y excreción de las mismas, en distintos organismos. La primera fase de cualquiera de estos estudios implica conocer la concentración total del elemento en distintos tipos de muestras biológicas. El principal objetivo de este trabajo es la determinación de plata en muestras biológicas mediante técnicas de espectroscopía atómica, basadas en atomización electrotérmica en horno de grafito. El trabajo incluye la optimización de los parámetros instrumentales y el uso de paladio como modificante químico, para favorecer la estabilidad térmica de la plata en el horno de grafito. Frente a los procedimientos convencionales de preparación de muestras biológicas para análisis de metales, basados en digestiones ácidas, en el presente trabajo se va a llevar a cabo una digestión alcalina con hidróxido de tetrametilamonio (TMAH). La ventaja del uso de TMAH es que mantiene la integridad de las nanopartículas de plata que pudieran estar presentes en las muestras, lo que permitiría su determinación selectiva mediante el uso de las técnicas adecuadas. El método desarrollado se aplicó al análisis de un material de referencia certificado de tipo biológico, obteniéndose unos resultados coherentes con el valor certificado, por lo que se consideró que el procedimiento empleado era perfectamente válido, para la determinación de plata en tejidos biológicos

Fabricación mediante fusión con laser y caracterización de compuestos de alúmina monocristalina

El objetivo del presente trabajo ha sido la fabricación de fibras monocristalinas de alúmina pura y dopada con metales de transición mediante fusión zonal asistida con láser. Se determinaron las condiciones óptimas para la obtención de fibras monocristalinas. Se llevó a cabo el estudio microestructural y mecánico de las muestras obtenidas

Fabricación mediante fusión con laser y caracterización de compuestos de alúmina monocristalina

El objetivo del presente trabajo ha sido la fabricación de fibras monocristalinas de alúmina pura y dopada con metales de transición mediante fusión zonal asistida con láser. Se determinaron las condiciones óptimas para la obtención de fibras monocristalinas, se llevó a cabo el estudio microestructural de las muestras obtenidas, sobre las cuales se realizaron ensayos mecánicos con el objetivo de caracterizar sus propiedades mecánicas

Production of biodiesel from vegetable oil and microalgae by fatty acid extraction and enzymatic esterification

The aim of this work was to obtain biodiesel (methyl esters) from the saponifiable lipids (SLs) fraction of the microalga Nannochloropsis gaditana, whose biomass dry weight contains 12.1 wt% of these lipids. SLs were extracted from the microalga as free fatty acids (FFAs) for subsequent transformation to methyl esters (biodiesel) by enzymatic esterification. Extraction as FFAs rather than as SLs allows them to be obtained with higher purity. Microalgal FFAs were obtained by direct saponification of lipids in the biomass and subsequent extraction-purification with hexane. Esterification of FFAs with methanol was catalysed by lipase Novozym 435 from Candida antarctica. Stability studies of this lipase in the operational conditions showed that the esterification degree (ED) attained with the same batch of lipase remained constant over six reaction cycles (36 h total reaction time). The optimal conditions attained for 4 g of FFAs were 25 ºC, 200 rpm, methanol/FFA molar ratio of 1.5:1, Novozym 435/FFA ratio of 0.025:1 w/w and 4 h reaction time. In these conditions the ED attained was 92.6%, producing a biodiesel with 83 wt% purity from microalgal FFAs. Several experimental scales were tested (from 4 to 40 g FFAs), and in all cases similar EDs were obtained

Ceramic supports with highly dense and aligned pores for moltencarbonate based CO2 separation membranes

Resumen del trabajo presentado a la XVII Conference Ceramics in Europe, celebrada en Krakow (Poland), del 10 al 14 de julio de 2022.Spanish Ministerio de Economía y Competitividad and Feder Funds grants MAT2016-77769R and BES-2017-079683; Departamento de Ciencia, Universidad y Sociedad del Conocimiento del Gobierno de Aragón through the financial support to the Research Group T02 20R.N

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication