La3TaO7 derivatives with Weberite structure type: Possible electrolytes for solid oxide fuel cells and high temperature electrolysers

In this study, with the aim to enhance the ionic conduction of known structures by defect chemistry, the La2O3-Ta2O5 system was considered with a focus on the La3TaO7 phase whose structure is of Weberite type. In order to predict possible preferential substitution sites and substitution elements, atomistic simulation was used as a first approach. A solid solution La3−xSrxTaO7−x/2 was confirmed by X-ray diffraction and Raman spectroscopy; it extends for a substitution ratio up to x = 0.15. Whereas La3TaO7 is a poor oxide ion conductor (σ700 °C = 2 × 10−5S.cm−1), at 700 °C, its ionic conductivity is increased by more than one order of magnitude when 3.3% molar strontium is introduced in the structure (σ700 °C = 2 × 10−4S.cm−1)

The Disease Burden of Taenia solium Cysticercosis in Cameroon

Taenia solium cysticercosis is a zoonotic disease occurring in many developing countries. A relatively high prevalence in humans and pigs has been reported in several parts of the world, but insufficient data are available on the disease burden. Disease impact assessment needs detailed information on well-defined epidemiological and economic parameters. Our work conducted in West Cameroon over several years allowed us to collect the necessary information to estimate the impact of the parasite on the human and animal populations in this area using both cost and Disability Adjusted Life Year (DALY) estimations. This study identified the professional inactivity caused by the disease as the major loss factor in comparison to the cost of health care and losses due to infected pigs. These findings should allow a simpler estimation of the global disease burden based on information on salary levels and human cysticercosis prevalence in endemic areas of the world. In addition, the number of DALYs lost was higher than estimates already available for some other neglected tropical diseases in sub-Saharan Africa

Use of Antihypertensives, Blood Pressure, and Estimated Risk of Dementia in Late Life

ImportanceThe utility of antihypertensives and ideal blood pressure (BP) for dementia prevention in late life remains unclear and highly contested.ObjectivesTo assess the associations of hypertension history, antihypertensive use, and baseline measured BP in late life (age >60 years) with dementia and the moderating factors of age, sex, and racial group.Data Source and Study SelectionLongitudinal, population-based studies of aging participating in the Cohort Studies of Memory in an International Consortium (COSMIC) group were included. Participants were individuals without dementia at baseline aged 60 to 110 years and were based in 15 different countries (US, Brazil, Australia, China, Korea, Singapore, Central African Republic, Republic of Congo, Nigeria, Germany, Spain, Italy, France, Sweden, and Greece).Data Extraction and SynthesisParticipants were grouped in 3 categories based on previous diagnosis of hypertension and baseline antihypertensive use: healthy controls, treated hypertension, and untreated hypertension. Baseline systolic BP (SBP) and diastolic BP (DBP) were treated as continuous variables. Reporting followed the Preferred Reporting Items for Systematic Review and Meta-Analyses of Individual Participant Data reporting guidelines.Main Outcomes and MeasuresThe key outcome was all-cause dementia. Mixed-effects Cox proportional hazards models were used to assess the associations between the exposures and the key outcome variable. The association between dementia and baseline BP was modeled using nonlinear natural splines. The main analysis was a partially adjusted Cox proportional hazards model controlling for age, age squared, sex, education, racial group, and a random effect for study. Sensitivity analyses included a fully adjusted analysis, a restricted analysis of those individuals with more than 5 years of follow-up data, and models examining the moderating factors of age, sex, and racial group.ResultsThe analysis included 17 studies with 34 519 community dwelling older adults (20 160 [58.4%] female) with a mean (SD) age of 72.5 (7.5) years and a mean (SD) follow-up of 4.3 (4.3) years. In the main, partially adjusted analysis including 14 studies, individuals with untreated hypertension had a 42% increased risk of dementia compared with healthy controls (hazard ratio [HR], 1.42; 95% CI 1.15-1.76; P = .001) and 26% increased risk compared with individuals with treated hypertension (HR, 1.26; 95% CI, 1.03-1.53; P = .02). Individuals with treated hypertension had no significant increased dementia risk compared with healthy controls (HR, 1.13; 95% CI, 0.99-1.28; P = .07). The association of antihypertensive use or hypertension status with dementia did not vary with baseline BP. There was no significant association of baseline SBP or DBP with dementia risk in any of the analyses. There were no significant interactions with age, sex, or racial group for any of the analyses.Conclusions and RelevanceThis individual patient data meta-analysis of longitudinal cohort studies found that antihypertensive use was associated with decreased dementia risk compared with individuals with untreated hypertension through all ages in late life. Individuals with treated hypertension had no increased risk of dementia compared with healthy controls

Determinants of cognitive performance and decline in 20 diverse ethno-regional groups: A COSMIC collaboration cohort study.

BACKGROUND: With no effective treatments for cognitive decline or dementia, improving the evidence base for modifiable risk factors is a research priority. This study investigated associations between risk factors and late-life cognitive decline on a global scale, including comparisons between ethno-regional groups. METHODS AND FINDINGS: We harmonized longitudinal data from 20 population-based cohorts from 15 countries over 5 continents, including 48,522 individuals (58.4% women) aged 54-105 (mean = 72.7) years and without dementia at baseline. Studies had 2-15 years of follow-up. The risk factors investigated were age, sex, education, alcohol consumption, anxiety, apolipoprotein E ε4 allele (APOE*4) status, atrial fibrillation, blood pressure and pulse pressure, body mass index, cardiovascular disease, depression, diabetes, self-rated health, high cholesterol, hypertension, peripheral vascular disease, physical activity, smoking, and history of stroke. Associations with risk factors were determined for a global cognitive composite outcome (memory, language, processing speed, and executive functioning tests) and Mini-Mental State Examination score. Individual participant data meta-analyses of multivariable linear mixed model results pooled across cohorts revealed that for at least 1 cognitive outcome, age (B = -0.1, SE = 0.01), APOE*4 carriage (B = -0.31, SE = 0.11), depression (B = -0.11, SE = 0.06), diabetes (B = -0.23, SE = 0.10), current smoking (B = -0.20, SE = 0.08), and history of stroke (B = -0.22, SE = 0.09) were independently associated with poorer cognitive performance (p < 0.05 for all), and higher levels of education (B = 0.12, SE = 0.02) and vigorous physical activity (B = 0.17, SE = 0.06) were associated with better performance (p < 0.01 for both). Age (B = -0.07, SE = 0.01), APOE*4 carriage (B = -0.41, SE = 0.18), and diabetes (B = -0.18, SE = 0.10) were independently associated with faster cognitive decline (p < 0.05 for all). Different effects between Asian people and white people included stronger associations for Asian people between ever smoking and poorer cognition (group by risk factor interaction: B = -0.24, SE = 0.12), and between diabetes and cognitive decline (B = -0.66, SE = 0.27; p < 0.05 for both). Limitations of our study include a loss or distortion of risk factor data with harmonization, and not investigating factors at midlife. CONCLUSIONS: These results suggest that education, smoking, physical activity, diabetes, and stroke are all modifiable factors associated with cognitive decline. If these factors are determined to be causal, controlling them could minimize worldwide levels of cognitive decline. However, any global prevention strategy may need to consider ethno-regional differences

In search of new electrolyte and cathode materials for SOFC : weberite and cobaltite

Avec pour objectif la recherche de nouveaux matériaux pour piles à combustible à oxyde solide, ce travail s’est orienté sur l’étude de nouveaux électrolytes, d’une part, et la caractérisation de nouveaux matériaux de cathode d’autre part. La première partie porte sur la caractérisation des phases de structure weberite, dérivées de La3TaO7. Une solution solide La3-xSrxTaO7-x/2 est mise en évidence pour 0≤x≤0,15. La substitution partielle du lanthane par le strontium permet d’augmenter la conductivité de La3TaO7 d’un facteur 1000. Les performances des matériaux obtenus restent, cependant, en-dessous de celle de la zircone stabilisée à l’yttrium. En outre, ces phases présentent des propriétés de conduction protonique, qui pourraient s’avérer intéressantes pour une utilisation comme membrane pour la séparation de l’hydrogène dans des procédés tels que le reformage des hydrocarbures. En parallèle, nous nous sommes aussi intéressés à la synthèse et la caractérisation de nouveaux matériaux de cathode à base de cobalt: Ba2Co9O14-d, Ca3Co2O6, YBaCo2O5+d, YBaCo4O7+d, et Ca3Co4O9-d en mettant l’accent sur l’influence des lacunes oxygénées et de la dimensionnalité de la structure. Les mesures électrochimiques ont été effectuées, et les meilleures performances sont obtenues pour les composés Ba2Co9O14-d, et Ca3Co4O9-d.With the aim to research new materials for Solid Oxid Fuel Cells, this work is focused on the study of new electrolyte materials, on one hand, and on the characterisation of new cathode materials, on the other hand. The first part concerns the characterisation of weberite structure derived from La3TaO7. A solid solution is evidenced for 0≤x≤0.15. The conductivity of La3TaO7 is increased by a factor of 1000 by partial substitution of lanthanum with strontium. However, the performances of materials remain under those of yttria stabilised zirconia. In addition, these phases display protonic conduction, which would be attractive for use as membrane for the hydrogen separation in hydrocarbon reforming. In parallel, new cathode materials were characterised. Cobaltites with different structural dimensionality were studied: Ba2Co9O14-d, Ca3Co2O6, YBaCo2O5+d, YBaCo4O7+d, and Ca3Co4O9-d. Several electrochemical measurements were carried out and best results were obtained for Ba2Co9O14-d, and Ca3Co4O9-

A la recherche de nouveaux matériaux d'électrolyte et de cathode pour SOFC (weberite et cobaltite)

Avec pour objectif la recherche de nouveaux matériaux pour piles à combustible à oxyde solide, ce travail s est orienté sur l étude de nouveaux électrolytes, d une part, et la caractérisation de nouveaux matériaux de cathode d autre part. La première partie porte sur la caractérisation des phases de structure weberite, dérivées de La3TaO7. Une solution solide La3-xSrxTaO7-x/2 est mise en évidence pour 0<=x<=0,15. La substitution partielle du lanthane par le strontium permet d augmenter la conductivité de La3TaO7 d un facteur 1000. Les performances des matériaux obtenus restent, cependant, en-dessous de celle de la zircone stabilisée à l yttrium. En outre, ces phases présentent des propriétés de conduction protonique, qui pourraient s avérer intéressantes pour une utilisation comme membrane pour la séparation de l hydrogène dans des procédés tels que le reformage des hydrocarbures. En parallèle, nous nous sommes aussi intéressés à la synthèse et la caractérisation de nouveaux matériaux de cathode à base de cobalt: Ba2Co9O14-d, Ca3Co2O6, YBaCo2O5+d, YBaCo4O7+d, et Ca3Co4O9-d en mettant l accent sur l influence des lacunes oxygénées et de la dimensionnalité de la structure. Les mesures électrochimiques ont été effectuées, et les meilleures performances sont obtenues pour les composés Ba2Co9O14-d, et Ca3Co4O9-d.With the aim to research new materials for Solid Oxid Fuel Cells, this work is focused on the study of new electrolyte materials, on one hand, and on the characterisation of new cathode materials, on the other hand. The first part concerns the characterisation of weberite structure derived from La3TaO7. A solid solution is evidenced for 0<=x<=0.15. The conductivity of La3TaO7 is increased by a factor of 1000 by partial substitution of lanthanum with strontium. However, the performances of materials remain under those of yttria stabilised zirconia. In addition, these phases display protonic conduction, which would be attractive for use as membrane for the hydrogen separation in hydrocarbon reforming. In parallel, new cathode materials were characterised. Cobaltites with different structural dimensionality were studied: Ba2Co9O14-d, Ca3Co2O6, YBaCo2O5+d, YBaCo4O7+d, and Ca3Co4O9-d. Several electrochemical measurements were carried out and best results were obtained for Ba2Co9O14-d, and Ca3Co4O9-dLILLE1-Bib. Electronique (590099901) / SudocSudocFranceF

Coeur et nucléolus des jeux de recouvrement

International audienc

Impact of geomechanical effects during SAGD process in a meander belt

In the reservoir simulations, the geomechanical effects are usually taken into account to describe the porosity and the permeability variations. In this paper, we present a new method, patented by authors, which allows to model the geomechanical effects also on the well productivity index. The Steam Assisted Gravity Drainage (SAGD) method is widely used for the heavy oil production. A very high variation in pressure and temperature play a significant role on the petrophysical properties and may impact the productivity estimation. In this paper we develop a new simplified geomechanical model in order to account for the thermal and pressure effects on the porosity, permeability and the productivity index during the reservoir simulation. At the current state, these dependencies are defined using semi-analytical relationships. The model is applied to a meandering fluvial reservoir based on 3D outcrop observations. The productivity is found underestimated if the pressure and temperature effects on the petrophysical properties are ignored in the reservoir simulation. Moreover, this study shows an important impact of thermal effects on the productivity estimation. The results of this work show that it is essential to properly take into account the geomechanical effects on the petrophysical properties and also on the productivity index for a better productivity estimation