Etude des boues résiduaires de la station de traitement des eaux de Ziga et examen de leur possible valorisation pour la confection de barrières étanches

Dans le contexte social, économique et environnemental actuel du développement durable, la production de boues de décantation dans les stations d’épuration est en constante augmentation et leur gestion requiert des moyens importants. Il est nécessaire d'examiner les nombreuses façons d'utiliser et d'optimiser cette production minérale. Prenant en compte les difficultés du pays, nous nous sommes concentrés sur la contribution combinée des mesures rhéologiques pour caractériser la cohérence et la capacité de faire couler la matière dans les procédés industriels et sur les mesures de filtration de la perméabilité du gâteauou membrane obtenue par filtration de suspension. Si la rhéologie est un outil performant, nécessitant l'expertise et des équipements coûteux, les tests de filtration sont simples et faciles à exécuter. A travers l'étude de nombreux paramètres (concentration, température, l’ajout de la bentonite), nous avons démontré que les boues de Ziga sont constitués de minéraux en partie des fines et de l’argile, ce qui pourrait être utilisé dans l’ingénierie environnementale et offrir une solution à la gestion efficace des déchets miniers avec le maximum de sécurité.Mots-clés : boues de Ziga, barrières étanches, filtration, perméabilité, rhéologie

Mechanical and physical properties of stabilised compressed coal bottom ash blocks with inclusion of lateritic soils in Niger

This is the final version. Available on open access from Elsevier via the DOI in this recordThis paper describes the results from an investigation on the production of compressed block made with coal combustion by-products and local clayey soil in Niger. Stabilisation with Portland cement and a mixture of Portland cement and lime was adopted. Mechanical, physical, hydric, and thermal characterisation of the produced bricks was carried out. Blocks with satisfactory compressive strength were produced, with samples consistently exceeding the compressive strength of 4 MPa. Stabilisation with Portland cement proved to be the most effective in terms of strength development. However, satisfactory results were obtained with partial substitution of cement with lime (up to 30%). Porosity was found to be in the range 33% to 40% for all samples. The low thermal conductivity (in the range 0.31 to 0.48 W/m•K) was presumably influenced by the high porosity. Water absorption of the bricks was found to be very fast, although total water absorption (in the range 20.6 to 28.7%) was lower than the calculated porosity, suggesting that some of the pores were not accessible by water. Samples subjected to heating showed very promising results in terms of strength and mass loss. An increase in compressive strength was recorded up to temperatures of 400°C. This might be due to the triggering of other reactions in the binding matrix due to the chemistry of the bottom ash. A change in colour of samples (from grey to red) was observed, due to the dehydroxilation of iron hydroxide turning into ferric oxide

Micronutrient Deficiencies in Medical and Surgical Inpatients

Inpatients are threatened by global malnutrition, but also by specific micronutrient (i.e., trace element and vitamins) deficiencies that frequently are overseen in the differential diagnosis of major organ dysfunctions. Some of them are related to specific geographic risks (iodine, iron, selenium, zinc, vitamin A), while others are pathology related, and finally many are associated with specific feeding patterns, including low dose enteral feeding. Among the pathologies in which laboratory blood investigations should include a micronutrient outwork, anemia is in the front line, followed by obesity with bariatric surgery, chronic liver disease, kidney disease, inflammatory bowel disease, cardiomyopathies and heart failure. The micronutrients at the highest risk are iron, zinc, thiamine, vitamin B12 and vitamin C. Admission to hospital has been linked with an additional risk of malnutrition-feeding below 1500 kcal/day was frequent and has been associated with a structural additional risk of insufficient micronutrient intake to cover basal needs. Although not evidence based, systematic administration of liberal thiamine doses upon admission, and daily complementation of inpatients' food and enteral feeding solutions with multi-micronutrient tablets might be considered

MDCT-findings in patients with non-occlusive mesenteric ischemia (NOMI): influence of vasoconstrictor agents.

To evaluate the influence of vasoconstrictor agents (VCAs) on signs of vasoconstriction and bowel ischemia on MDCT detected in patients with non-occlusive mesenteric ischemia (NOMI). This 8-year single-center retrospective study consecutively included all patients with histopathologically proven NOMI who underwent MDCT ≤ 48 h prior to surgical bowel resection. Two blinded radiologists jointly reviewed each examination for signs of bowel ischemia, abdominal organ infarct, mesenteric vessel size and regularity, and ancillary vascular findings. VCA administration (length and dosage), clinical and biochemical data, risk factors, and outcomes were retrieved from patients' medical records. Subgroup comparisons were performed. Ninety patients were included (59 males, mean age 65 years); 40 (44.4%) had received VCAs before MDCT. Overall mortality was 32% (n = 29), with no significant difference between the two groups. In patients treated with VCAs, the calibre of the superior mesenteric artery (SMA) was smaller (p = 0.032), and vasoconstriction of its branches tended to be more important (p = 0.096) than in patients not treated with VCAs. The presence and extent of bowel ischemia did not significantly correlate with VCA administration, but abdominal organ infarcts tended to be more frequent (p = 0.005) and involved more organs (p = 0.088). The VCA group had lower mean arterial pressure (p = 0.006) and lower hemoglobin levels (p < 0.001). Several biomarkers of organ failure and inflammation, differed significantly with VCA use, proving worse clinical condition. MDCT demonstrates more severe SMA vasoconstriction and tends to show increased abdominal organ infarcts after VCA administration in NOMI patients compared to NOMI patients not treated with VCAs. • In critically ill patients with NOMI, MDCT demonstrates VCA support via increased vasoconstriction of the main SMA and its branches. • VCA administration in NOMI patients tends to contribute to the development of organ infarcts, as shown on MDCT. • An important degree of vasoconstriction in NOMI patients may indicate insufficient resuscitation and, thus, help clinicians in further patient management

Etude des propriétés viscoélastiques de suspensions de smectite homoionique à bi-ioniques (Ca2+, Na+) : influence de la concentrations (4 % à 10 %).

Une smectite est un phillosilicate 2/1 composé de feuillets chargés négativement susceptibles de s'associer en particules puis en un réseau tridimensionnel. Notre objectif est de comprendre l'influence des cations échangeables (Ca2+ et Na+) situés en position interfoliaire sur la structuration des suspensions. Des essais d'écoulement révèlent une évolution du comportement rhéologique allant de newtonien à rhéofluidifiant à seuil en fonction de la concentration et du cation saturant. Les suspensions sodiques forment des mélanges plus interactifs que les suspensions calciques, son influence est détectable dès 20 % de part de sodium dans les suspensions bi-ioniques. Les courbes d'écoulement sont analysées avec le modèle d'Herschel-Bulkley ce qui permet de rendre compte des différences de comportement, mais n'intègre pas le caractère thixotrope des suspensions. L'augmentation de la fraction sodique des suspensions bi-ioniques permet la formation d'un gel aux propriétés viscoélastiques caractérisées à l'aide d'essais de fluage et d'oscillation

Mimicking Alpine thrusts by orogenic passive deformation of synsedimentary normal faults: a record of Jurassic extension of the European margin (Mont Fort nappe, Middle Penninic, Western Alps)

The Mont Fort nappe is the upper tectonic subdivision of the former Grand St-Bernard (GSB) nappe (Escher 1988, Escher et al. 1997). Subsequent research has confirmed its tectonic and stratigraphic independence from the rest of the GSB nappe (e.g. Gouffon 1993). It consists of a Paleozoic basement overlain by a thin Mesozoic sedimentary cover, comprised of very thin, discontinuous Triassic quartzite and dolomite, a thin limestone layer, and for the greater part of breccias of variable thickness mostly made of dolomitic elements (“reconstituted Triassic”). These breccias are overlain by a more massive limestone topped by a thinner upper breccia rich in elements of quartzite. Called by Escher (1988) the Evolène series, this sequence presents remarkable similarities with the stratigraphic column of the Breccia nappe in the Prealps which typically belongs to the Prepiemontese paleogeographic domain (Lemoine 1961, Escher 1988). This similarity strongly suggests an earliest Jurassic age for the lower limestone, a late Early to Middle Jurassic age for the main mass of breccias (Lower Breccia), and a Late Jurassic to earliest Cretacous age for the upper limestone and the Upper Breccia. We will not discuss here the status of the Cretaceous calcschists (Série Rousse, Marthaler 1984) that overlie the Evolène series and are the subject of research in progress. These ages are generally accepted. However, several authors proposed a different tectonic model where the Evolène series would be allochthonous over the Mont Fort basement (e.g. Sartori & Marthaler 1994, Marthaler et al. 2008). Their contact would be an Alpine thrust. The main argument would be that this contact surface often cuts with an angular discordance the stratigraphy of the Evolène series. Consequently, this series would not be the original sedimentary cover of the Mont Fort basement but would belong to a distinct tectonic unit that these authors identified with the Cima Bianca nappe (classically defined as a slice of Late Paleozoic to Mesozoic sediments separating the ophiolitic Zermatt-Saas and Tsaté nappes; Vannay & Allemann 1990, Steck et al. 2015). This proposition has been widely accepted (e.g. Tectonic map of Switzerland 2005). Our observations don’t support this proposition. They rather confirm the tectonic reconstruction of Escher (1988) and suggest that the Evolène series is indeed the autochthonous cover of the Mont Fort basement. The main points are: - At many places the contact is concordant and shows a good preservation of the basal levels of the Mesozoic sequence, without any hint of tectonic disturbance or anomalous rock deformation. - The discordance observed at other places, which can put the Jurassic breccia in contact with all older formations, can be conveniently explained by synsedimentary normal paleofaults. By means of strain theory (e.g. Ramsay 1967) it is easy to demonstrate that passive deformation of such faults during Alpine compression can mimic thrusts. - The sedimentary characteristics of the Evolène series, typicall of the Prepiemontese domain, are very different from those of the Cima Bianca unit, much poorer in breccias and whose relatively thick Triassic formations of quartzite and carbonates show a Briançonnais affinity. Conclusion : The Evolène series is the sedimentary cover of the Mont Fort nappe. During Jurassic times it has been strongly affected by synsedimentary normal faulting, generating stratigraphic gaps, synsedimentary anomalous contacts and internal discordances. These structures provide a spectacular record of the extension of the European margin during the opening of the Alpine Tethys. Then Alpine compression passively deformed these faults in such a way that they mimic Alpine thrusts. REFERENCES Escher, A. 1988: Structure de la nappe du Grand Saint-Bernard entre le val de Bagnes et les Mischabel. Service hydrologique et géologique national, Berne. Escher, A., Hunziker, J., Marthaler, M., Masson, H., Sartori, M., & Steck, A. 1997: Geologic framework and structural evolution of the western Swiss-Italian Alps. In O. A. Pfiffner et al. (Eds.): Deep structure of the Swiss Alps: results of NRP 20, 205–221. Birkhaüser, Basel. Gouffon, Y. 1993: Géologie de la «nappe» du Grand St-Bernard entre la Doire Baltée et la frontière suisse (Vallée d’Aoste, Italie). Mém. Geol. (Lausanne) 12. Marthaler, M., Sartori, M., Escher, A. & Meisser, N. 2008. Feuille 1307 Vissoie. Atlas géologique Suisse 1:25’000, Carte et Notice explicative 122. Sartori, M. & Marthaler, M. 1994: Exemples de relations socle-couverture dans les nappes penniques du Val d’Hérens. C.-r. Excursion Soc. Géol. Suisse et Soc. Suisse Minér. Pétr., Schweiz. Miner. Petr. Mitt. 74, 503-509

Simple equations to predict the effects of veno-venous ECMO in decompensated Eisenmenger syndrome.

Adult patients with uncorrected congenital heart diseases and chronic intracardiac shunt may develop Eisenmenger syndrome (ES) due to progressive increase of pulmonary vascular resistance, with significant morbidity and mortality. Acute decompensation of ES in conditions promoting a further increase of pulmonary vascular resistance, such as pulmonary embolism or pneumonia, can precipitate major arterial hypoxia and death. In such conditions, increasing systemic oxygenation with veno-venous extracorporeal membrane oxygenation (VV-ECMO) could be life-saving, serving as a bridge to treat a potential reversible cause for the decompensation, or to urgent lung transplantation. Anticipating the effects of VV-ECMO in this setting could ease the clinical decision to initiate such therapeutic strategy. Here, we present a series of equations to accurately predict the effects of VV-ECMO on arterial oxygenation in ES and illustrate this point by a case of ES decompensation with refractory hypoxaemia consecutive to an acute respiratory failure due to viral pneumonia

Venous thromboembolism in critically Ill patients with COVID-19: Results of a screening study for deep vein thrombosis.

The rapid spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and coronavirus disease 2019 (COVID-19), has caused more than 3.9 million cases worldwide. Currently, there is great interest to assess venous thrombosis prevalence, diagnosis, prevention, and management in patients with COVID-19. To determine the prevalence of venous thromboembolism (VTE) in critically ill patients with COVID-19, using lower limbs venous ultrasonography screening. Beginning March 8, we enrolled 25 patients who were admitted to the intensive care unit (ICU) with confirmed SARS-CoV-2 infections. The presence of lower extremity deep vein thrombosis (DVT) was systematically assessed by ultrasonography between day 5 and 10 after admission. The data reported here are those available up to May 9, 2020. The mean (± standard deviation) age of the patients was 68 ± 11 years, and 64% were men. No patients had a history of VTE. During the ICU stay, 8 patients (32%) had a VTE; 6 (24%) a proximal DVT, and 5 (20%) a pulmonary embolism. The rate of symptomatic VTE was 24%, while 8% of patients had screen-detected DVT. Only those patients with a documented VTE received a therapeutic anticoagulant regimen. As of May 9, 2020, 5 patients had died (20%), 2 remained in the ICU (8%), and 18 were discharged (72%). In critically ill patients with SARS-CoV-2 infections, DVT screening at days 5-10 of admission yielded a 32% prevalence of VTE. Seventy-five percent of events occurred before screening. Earlier screening might be effective in optimizing care in ICU patients with COVID-19

A first update on mapping the human genetic architecture of COVID-19

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