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Search Results: 1 - 10 of 1936 matches for " Murielle Bertrand "
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Method to Study the Primary Nucleation for Solid Solution: Application to Uranium-Neodymium Oxalate Coprecipitation  [PDF]
Delphine Parmentier, Murielle Bertrand, Edouard Plasari, Pascal Baron
Crystal Structure Theory and Applications (CSTA) , 2013, DOI: 10.4236/csta.2013.22011
Abstract: Actinides co-precipitation is currently investigated in order to synthesize solid solutions of actinides mixed oxalates. This paper deals with the thermodynamic and kinetic study of the precipitation of uranium-neodymium oxalate system. Based on an analysis of the theories developed in the literature, a new expression for the determination of the supersaturation ratio for the solid solutions is presented. An experimental study of the nucleation kinetics was performed on the mixed uranium-neodymium oxalates. Homogeneous and heterogeneous primary nucleation laws are obtained using a specific stopped flow apparatus. The experimental results are consistent with the classical behaviour of nucleation phenomena. The values of the kinetic parameters for the solid solution point out that the formation of the uraniumneodymium mixed oxalates is kinetically favoured compared with the simple uranium and neodymium oxalates.
Mixing Study in an Unbaffled Stirred Precipitator Using LES Modelling
Murielle Bertrand,Delphine Parmentier,Olivier Lebaigue,Edouard Plasari,Frédéric Ducros
International Journal of Chemical Engineering , 2012, DOI: 10.1155/2012/450491
Abstract: This paper describes the CFD modelling of a reactor operating in the nuclear industry using LES approach. The reactor consists of an unbaffled stirred tank reactor in which plutonium precipitation reactions are carried out. The flow generated in such a precipitator is complex and there is very little information available in the literature about unbaffled reactors stirred with magnetic rod. That is why a hydrodynamic modelling has been developed using computational fluid dynamics (CFD) in order to get accurate description of mixing phenomena inside the precipitator and therefore to be able to predict the solid particle properties. Due to the strong turbulence anisotropy, the turbulence transport simulation is achieved by a large eddy simulation (LES) approach which gives unsteady solutions. The numerical simulations are performed in 3D using the Trio_U code developed at the Commissariat à l'énergie Atomique. The predictive performances of the modelling are analysed through a mixing phenomena study. Both experimental and numerical studies are performed. This work shows how hydrodynamics inside the reactor can have a noticeable effect on the precipitate properties and how LES modelling is a very effective tool for the process control. 1. Introduction Owing to the manipulation of radioactive materials at large scale, nuclear industry has to implement reactors with unusual design. An unbaffled magnetic rod-stirred reactor thus has been developed in the spent nuclear fuel reprocessing industry for use as a precipitator [1, 2]. Precipitation reactions being very fast are well known to be highly sensitive to mixing effects. That is why an accurate knowledge of the hydrodynamics inside the reactor is particularly essential to control the quality of the solid particles formed, on the one hand, and to develop a global modelling of the precipitation process, on the other hand. Flows in stirred unbaffled vessels have not been widely discussed in the literature, unlike stirred baffled vessels, because they are less frequently used in processes [2–4]. Their mixing performance is significantly lower due to the predominance of the tangential velocity over the axial and radial velocity components. Without counterimpellers, however, fluid rotation leads to the formation of a vortex that distorts the free surface; some applications can take advantage of this vortex. In the precipitator considered here, this configuration limits scaling by maintaining potentially adhering particles away from the walls and thus facilitates maintenance procedures that are particularly
Plasma PCSK9 concentrations during an oral fat load and after short term high-fat, high-fat high-protein and high-fructose diets
Cariou Bertrand,Langhi Cédric,Le Bras Ma?lle,Bortolotti Murielle
Nutrition & Metabolism , 2013, DOI: 10.1186/1743-7075-10-4
Abstract: Background PCSK9 (Proprotein Convertase Subtilisin Kexin type 9) is a circulating protein that promotes hypercholesterolemia by decreasing hepatic LDL receptor protein. Under non interventional conditions, its expression is driven by sterol response element binding protein 2 (SREBP2) and follows a diurnal rhythm synchronous with cholesterol synthesis. Plasma PCSK9 is associated to LDL-C and to a lesser extent plasma triglycerides and insulin resistance. We aimed to verify the effect on plasma PCSK9 concentrations of dietary interventions that affect these parameters. Methods We performed nutritional interventions in young healthy male volunteers and offspring of type 2 diabetic (OffT2D) patients that are more prone to develop insulin resistance, including: i) acute post-prandial hyperlipidemic challenge (n=10), ii) 4 days of high-fat (HF) or high-fat/high-protein (HFHP) (n=10), iii) 7 (HFruc1, n=16) or 6 (HFruc2, n=9) days of hypercaloric high-fructose diets. An acute oral fat load was also performed in two patients bearing the R104C-V114A loss-of-function (LOF) PCSK9 mutation. Plasma PCSK9 concentrations were measured by ELISA. For the HFruc1 study, intrahepatocellular (IHCL) and intramyocellular lipids were measured by 1H magnetic resonance spectroscopy. Hepatic and whole-body insulin sensitivity was assessed with a two-step hyperinsulinemic-euglycemic clamp (0.3 and 1.0 mU.kg-1.min-1). Findings HF and HFHP short-term diets, as well as an acute hyperlipidemic oral load, did not significantly change PCSK9 concentrations. In addition, post-prandial plasma triglyceride excursion was not altered in two carriers of PCSK9 LOF mutation compared with non carriers. In contrast, hypercaloric 7-day HFruc1 diet increased plasma PCSK9 concentrations by 28% (p=0.05) in healthy volunteers and by 34% (p=0.001) in OffT2D patients. In another independent study, 6-day HFruc2 diet increased plasma PCSK9 levels by 93% (p<0.0001) in young healthy male volunteers. Spearman’s correlations revealed that plasma PCSK9 concentrations upon 7-day HFruc1 diet were positively associated with plasma triglycerides (r=0.54, p=0.01) and IHCL (r=0.56, p=0.001), and inversely correlated with hepatic (r=0.54, p=0.014) and whole-body (r= 0.59, p=0.0065) insulin sensitivity. Conclusions Plasma PCSK9 concentrations vary minimally in response to a short term high-fat diet and they are not accompanied with changes in cholesterolemia upon high-fructose diet. Short-term high-fructose intake increased plasma PCSK9 levels, independent on cholesterol synthesis, suggesting a regulation indep
Quand l’écriture c’est un tableau : La maison imaginaire chiriquienne
Murielle Martin
Voix Plurielles , 2010,
Abstract: Dans cet article, il est question du peintre Giorgio de Chirico qui ne travaille pas seulement une surface à peindre mais construit des lieux imaginaires où tout évolue selon le parcours de recherche du texte narratif d'Hebdomeros. Il semble alors intéressant de croiser l'approche de la réalisation picturale de La Tour Rouge (1913) comme résultat littéraire et pictural de la Maison imaginaire de l'artiste.
Reflections on a Marine Venus (1953) : le détour par Rhodes dans la trilogie des les de Lawrence Durrell
E-rea : Revue électronique d’études sur le Monde Anglophone , 2005, DOI: 10.4000/erea.535
Abstract: Il s’agit ici de s’interroger sur la place qu’occupe le deuxième récit de voyage dans la trilogie durrellienne composée de Prospero’s Cell, publié en 1945 et consacré à l’ le de Corfou, où Durrell a séjourné de 1935 à 1941, de Reflections on a Marine Venus, publié en 1953 et consacré à l’ le de Rhodes suite à un séjour effectué de 1945 à 1947 et de Bitter Lemons, publié en 1957 après le séjour de Durrell à Chypre de 1953 à 1956. Cette étude vise ainsi à apporter un complément à la récente con...
Les ressorts de l’essor de la société civile en Guadeloupe Springs of expansion of civil society in Guadeloupe
Murielle Vairac
études Caribeénnes , 2012, DOI: 10.4000/etudescaribeennes.4898
Abstract: Les effets de la crise du capitalisme se sont traduits en Guadeloupe en janvier 2009 par un mouvement social sans précédent, dirigé par un collectif qui a suscité l’adhésion en raison de son expression du malaise social et de la gestion des revendications adressées au gouvernement. Ce mouvement social est innovant en Guadeloupe en raison de la pluralité des acteurs et de la nature de ses revendications. C’est donc sur son sens qu’il convient de s’interroger. Une société civile s’est réveillée créant de nouveaux espaces de débat. Capitalism’s crisis effects resulted in social movement unprecedented led by a group that mobilized in the style of expressing unrest and managing demands that were sent to French government. This social movement is new in Guadeloupe because of variety actions and type of demands. It’s therefore necessary to consider its meaning: a civil society woke up creating new spaces for debate.
Usefulness of Mendelian Randomization in Observational Epidemiology
Murielle Bochud,Valentin Rousson
International Journal of Environmental Research and Public Health , 2010, DOI: 10.3390/ijerph7030711
Abstract: Mendelian randomization refers to the random allocation of alleles at the time of gamete formation. In observational epidemiology, this refers to the use of genetic variants to estimate a causal effect between a modifiable risk factor and an outcome of interest. In this review, we recall the principles of a “Mendelian randomization” approach in observational epidemiology, which is based on the technique of instrumental variables; we provide simulations and an example based on real data to demonstrate its implications; we present the results of a systematic search on original articles having used this approach; and we discuss some limitations of this approach in view of what has been found so far.
Zwanzig-Mori projection operators and EEG dynamics: deriving a simple equation of motion
David Hsu, Murielle Hsu
BMC Biophysics , 2009, DOI: 10.1186/1757-5036-2-6
Abstract: PACS code: 87.19.ljThe electrical activity of the brain has intrigued scientists since the invention of the electroencephalogram (EEG) [1,2]. Scalp and intracranial EEG's are now in widespread clinical use in the diagnosis and management of epilepsy and other neurological disorders. These applications rely on empirical correlations between certain EEG patterns with specific neurological disorders. Intense interest exists in trying to understand EEG dynamics at a deeper level, so as to extract ever more information about brain health and function. These efforts fall into two classes: those which are largely empirical, based on traditional correlations between EEG patterns and clinical observations, and those which are theory-based, where one has in mind a certain model of brain dynamics and then one tries to interpret EEG patterns in terms of the theoretical model. In the empirical class are recent efforts to correlate high frequency oscillations with epileptogenic tissue [3]. In the theory-based class, the most celebrated approach is the cable theory of Hodgkin and Huxley [4]. This theory can be scaled up using compartmental models to describe networks of thousands or even millions of neurons using high power computers. In the hands of a master, much insight can come from such simulations [5]. However, these methods are computationally intensive. They are not easily scaled to truly macroscopic levels and they are not amenable to the clinical diagnostic situation where one wants to know, for specific EEG samples from specific individuals, whether a certain brain pathology is present.Mesoscopic and macroscopic level theories of EEG dynamics have also been proposed, each based on a plausible basic postulate or mathematical model of the electrical activity of the brain [2,6-8]. The methods of nonlinear dynamics (chaos theory) also fall into this class and have been applied to seizure prediction [9,10].It would be desirable to base a macroscopic theory of EEG dynamics on
Potential applications of curcumin and its novel synthetic analogs and nanotechnology-based formulations in cancer prevention and therapy
Murielle Mimeault, Surinder K Batra
Chinese Medicine , 2011, DOI: 10.1186/1749-8546-6-31
Abstract: The deregulation and sustained activation of multiple tumorigenic pathways are typically implicated in cancer development and progression to locally advanced, aggressive and metastatic stages as well as in treatment resistance and disease relapse [1-5]. Consequently, the use of therapeutic agents acting on different deregulated gene products, alone or in combination therapy, may represent a potentially better strategy than the targeting of one specific oncogenic product to overcome treatment resistance and prevent cancer development and disease recurrence [1-5]. The non-toxic substance curcumin is the major bioactive ingredient extracted from the rhizome of the plant Curcuma longa Linn, also as known as turmeric [6,7]. Curcumin has been used as a dietary supplement as well as a therapeutic agent in Chinese medicine and other Asian medicines for centuries [6,7]. Recently, curcumin, which is a polyphenolic compound, has emerged worldwide as a potent therapeutic substance for treating diverse human diseases. Curcumin displays a wide range of pharmacological properties against various human disorders, such as metabolic and infectious diseases, diabetes, psoriasis, rheumatoid arthritis, atherosclerosis, Parkinson's and Alzheimer's diseases and cancer [6-14].In vitro and in vivo studies have indicated that curcumin induces chemopreventive and chemotherapeutic effects against various types of human cancers. More specifically, curcumin exhibits anticarcinogenic effects on leukemias, lymphomas, multiple myeloma, brain cancer and melanoma as well as skin, cervix, lung, prostate, breast, ovarian, bladder, liver, gastrointestinal tract, pancreatic and colorectal epithelial cancers [2,9,15-36]. Curcumin displays strong anti-inflammatory, antioxidant, anti-aging, chemopreventive, antitumoral, anti-angiogenic, anti-metastatic, radiosensitizing and chemosensitizing effects in cancer cells in a concentration- and cell type-dependent manner (Figures 1 and 2) [2,7,9,10,22,37-39]. Of t
Novel biomarkers and therapeutic targets for optimizing the therapeutic management of melanomas
Murielle Mimeault,Surinder K Batra
World Journal of Clinical Oncology , 2012, DOI: 10.5306/wjco.v3.i3.32
Abstract: Cutaneous malignant melanoma is the most aggressive form of skin cancer with an extremely poor survival rate for the patients diagnosed with locally invasive and metastatic disease states. Intensive research has led in last few years to an improvement of the early detection and curative treatment of primary cutaneous melanomas that are confined to the skin by tumor surgical resection. However, locally advanced and disseminated melanomas are generally resistant to conventional treatments, including ionizing radiation, systemic chemotherapy, immunotherapy and/or adjuvant stem cell-based therapies, and result in the death of patients. The rapid progression of primary melanomas to locally invasive and/or metastatic disease states remains a major obstacle for an early effective diagnosis and a curative therapeutic intervention for melanoma patients. Importantly, recent advances in the melanoma research have led to the identification of different gene products that are often implicated in the malignant transformation of melanocytic cells into melanoma cells, including melanoma stem/progenitor cells, during melanoma initiation and progression to locally advanced and metastatic disease states. The frequent deregulated genes products encompass the oncogenic B-RafV600E and N-RasQ61R mutants, different receptor tyrosine kinases and developmental pathways such as epidermal growth factor receptor (EGFR), stem cell-like factor (SCF) receptor KIT, hedgehog, Wnt/β-catenin, Notch, stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor-4 (CXCR4) and vascular endothelial growth factor (VEGF)/VEGFR receptor. These growth factors can cooperate to activate distinct tumorigenic downstream signaling elements and epithelial-mesenchymal transition (EMT)-associated molecules, including phosphatidylinositol 3’-kinase (PI3K)/Akt/ molecular target of rapamycin (mTOR), nuclear factor-kappaB (NF-κB), macrophage inhibitory cytokine-1 (MIC-1), vimentin, snail and twist. Of therapeutic relevance, these deregulated signal transduction components constitute new potential biomarkers and therapeutic targets of great clinical interest for improving the efficacy of current diagnostic and prognostic methods and management of patients diagnosed with locally advanced, metastatic and/or relapsed melanomas.
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