Implementation of a Design Space Approach for Enantiomeric Separations in Polar Organic Solvent Chromatography

in Journal of Pharmaceutical & Biomedical Analysis (2013), 74

This paper focuses on implementing a Design Space approach and on the critical process parameters (CPPs) to consider when applying the Quality by Design (QbD) concepts outlined in ICH Q8(R2), Q9 and Q10 ... [more ▼]

This paper focuses on implementing a Design Space approach and on the critical process parameters (CPPs) to consider when applying the Quality by Design (QbD) concepts outlined in ICH Q8(R2), Q9 and Q10 to analytical method development and optimization for three chiral compounds developed as modulators of small conductance calcium-activated potassium (SK) channels. In this sense, an HPLC method using a polysaccharide-based stationary phase containing a cellulose tris (4-chloro-3-methylphenylcarbamate) chiral selector in polar organic solvent chromatography mode was considered. The effects of trifluoroacetic acid (TFA) and n-hexane concentration in an acetonitrile (MeCN) mobile phase were investigated under a wide range of column temperatures. Good correlations were found between the observed data obtained after using a central composite design and the expected chromatographic behaviours predicted by applying the design of experiments-design space (DoE-DS) methodology. The critical quality attribute represented here by the separation criterion (Scrit) allowed assessing the quality of the enantioseparation. Baseline separation for the compounds of interest in an analysis time of less than 20 minutes was possible due to the original and powerful tools applied which facilitated an enhanced method comprehension. Finally, the advantage of the DoE-DS approach resides in granting the possibility to concurrently assess robustness and identify the optimal conditions which are compound dependent. [less ▲]

Experiments with the interior-point method for solving large scale Optimal Power Flow problems

in Electric Power Systems Research (2013), 95

This paper reports extensive results obtained with the interior-point method (IPM) for nonlinear programmes (NLPs) stemming from large-scale and severely constrained classical Optimal Power Flow (OPF) and ... [more ▼]

This paper reports extensive results obtained with the interior-point method (IPM) for nonlinear programmes (NLPs) stemming from large-scale and severely constrained classical Optimal Power Flow (OPF) and Security-Constrained Optimal Power Flow (SCOPF) problems. The paper discusses transparently the problems encountered such as convergence reliability and speed issues of the method. [less ▲]

Psychologie et psychologisme

Book published by Vrin - à paraître (2013)

L’objectif de ce volume est de faire le point sur la question du psychologisme. Nous voudrions examiner non pas, comme cela est fait traditionnellement, pourquoi et comment il faut critiquer ce type de ... [more ▼]

L’objectif de ce volume est de faire le point sur la question du psychologisme. Nous voudrions examiner non pas, comme cela est fait traditionnellement, pourquoi et comment il faut critiquer ce type de position, mais aller au cœur du problème pour comprendre qu’est-ce que les auteurs qui ont adopté ce point de vue comptaient gagner et quel est, plus précisément, le rapport entre psychologisme et psychologie. C'est ainsi qu’une éventuelle réfutation du psychologisme pourra se fonder dans une véritable compréhension des enjeux et des nuances de cette position. Le psychologisme s’impose comme problème à cause du paradoxe qu’il engendre : d’une part la logique est une des dimensions de la pensée, et donc elle est partie intégrante du domaine de la psychologie. D’autre part, la psychologie elle même prétend être une science et donc elle doit se soumettre aux lois de la logique. La question du psychologisme est donc, en réalité, la question de savoir si c'est bien la logique qui se fonde sur les données de la psychologie ou bien si c'est la psychologie qui doit prendre comme fondement les lois de la logique. On le sait, le terme « psychologisme » a été utilisé surtout par les antipsychologistes, et en un sens péjoratif, pour désigner la prétention de fonder la logique dans la psychologie et de chercher par là-même les fondements de la vérité dans des lois psychologiques qui régissent la connaissance en tant qu’activité concrète de penser. La conséquence souvent déplorée de ce point de vue est que la connaissance - et la vérité qui en est la condition - se trouvent ainsi relativisées : nous entendons désormais par connaissance une activité empirique qui dépend de l’histoire personnelle du sujet connaissant et qui n’a pas de sens indépendamment de ce sujet. Si les arguments « anti-psychologistes », qui ont été formulés à la fin du XIXe siècle par Bolzano, Frege et Husserl entre autres, semblent l’avoir emporté avec succès, nous voudrions inviter les contributeurs à une réflexion sur les effets que cette critique a eu sur la psychologie entendue en un sens large. La psychologie, en tant que science des phénomènes psychiques, se réduit-elle à une prétention psychologiste sur la connaissance ? Ni a-t-il des questions que la psychologie soulève et se donne les moyens de résoudre, qui font de la psychologie un domaine légitime et fécond de la philosophie ? La question en travail sera donc : faut-il être psychologiste pour être psychologue ? Et implicitement il y a-t-il encore un intérêt pour le philosophe de chercher des réponses dans la psychologie et à quelles questions ? Nous proposons donc comme but de ce volume de mesurer d’une part le thème psychologiste concernant la théorie de la connaissance aux autres thèmes, peut-être plus convaincantes, que la psychologie avance à cette époque et d’autre part de mesurer l’effet que les arguments anti-psychologistes ont eu par la suite sur l’évolution de la psychologie comme science et sur sa pertinence philosophique. Nous discuterons cette problématique à partir de Kant et jusqu’à Husserl et Frege, en passant par Fries, Herbart, Beneke, Brentano et Stumpf. Le volume inclura (sous réserve de confirmation) les contributions de Jocelyn Benoist (Université Paris 1, Archives Husserl Paris), Rudolf Bernet (KU Leuven), Federico Boccaccini (ULg), Christian Bonnet (Université Paris 1), Arnaud Dewalque (ULg), Raphaël Ehrsam (Université Paris 1), Denis Fisette (Université du Québec à Montréal), Maria Gyemant (ULg), Martin Kusch (Université de Vienne), Carole Maigné (Université Paris IV, Archives Husserl Paris) et Denis Seron (ULg). [less ▲]

Modeling and Prediction of Nonlinear Environmental System Using Bayesian Methods

in Computers & Electronics in Agriculture (2013), 92

An environmental dynamic system is usually modeled as a nonlinear system described by a set of nonlinear ODEs. A central challenge in computational modeling of environmental systems is the determination ... [more ▼]

An environmental dynamic system is usually modeled as a nonlinear system described by a set of nonlinear ODEs. A central challenge in computational modeling of environmental systems is the determination of the model parameters. In these cases, estimating these variables or parameters from other easily obtained measurements can be extremely useful. This work addresses the problem of monitoring and modeling a leaf area index and soil moisture model (LSM) using state estimation. The performances of various conventional and state-of-the-art state estimation techniques are compared when they are utilized to achieve this objective. These techniques include the extended Kalman filter (EKF), the particle filter (PF), and the more recently developed technique variational filter (VF). Specifically, two comparative studies are performed. In the first comparative study, the state variables (the leaf-area index LAI , the volumetric water content of the soil layer 1, HUR1 and the volumetric water content of the soil layer 2, HUR2) are estimated from noisy measurements of these variables, and the various estimation techniques are compared by computing the estimation root mean square error (RMSE) with respect to the noise-free data. In the second comparative study, the state variables as well as the model parameters are simultaneously estimated. In this case, in addition to comparing the performances of the various state estimation techniques, the effect of number of estimated model parameters on the accuracy and convergence of these techniques are also assessed. The results of both comparative studies show that the PF provides a higher accuracy than the EKF, which is due to the limited ability of the EKF to handle highly nonlinear processes. The results also show that the VF provides a significant improvement over the PF because, unlike the PF which depends on the choice of sampling distribution used to estimate the posterior distribution, the VF yields an optimum choice of the sampling distribution, which also accounts for the observed data. The results of the second comparative study show that, for all techniques, estimating more model parameters affects the estimation accuracy as well as the convergence of the estimated states and parameters. However, the VF can still provide both convergence as well as accuracy related advantages over other estimation methods. [less ▲]

Prediction of residual stresses by FE simulations on bimetallic work rolls during cooling

in Computer Methods in Materials Science (2013), 13(1), 84-91

Bimetallic rolls used in the roughing stands of the Hot Strip Mill require mixed properties as a high wear resistance for the shell material and an enhanced toughness for the core material. The bimetallic ... [more ▼]

Bimetallic rolls used in the roughing stands of the Hot Strip Mill require mixed properties as a high wear resistance for the shell material and an enhanced toughness for the core material. The bimetallic roll studied in this paper is obtained from a vertical spin casting process followed by cooling and subsequent heat treatments. Failure of the compound roll sometimes occurs during the cooling stage of the casting route or later during the thermal treatments. It requires to deeply investigate the thermo mechanical metallurgical interactions generated during cooling and heat treatment in order to find the origin of cracks. For this purpose, a thermo metallurgic mechanical finite element model is used. However these numerical simulations require a high amount of mechanical, thermal and metallurgical parameters. In order to determinate these parameters, a study of available data for estimation of mechanical parameters was performed. Thermo physical parameters were obtained by DTA and DSC methods. Metallurgical characterization by inverse numerical method based on available CCT diagrams was performed to determine the TTT diagrams. First cooling numerical simulations are presented, allowing a rough estimate of residual stresses values and the identification of key parameters for predicting accurate residual stresses by sensitivity analysis. [less ▲]

3D-Characterization of the veneer-zirconia interface using FIB nano-tomography.

in Dental materials : official publication of the Academy of Dental Materials (2013), 29(2), 157-65

OBJECTIVES: The phenomena occurring during zirconia frameworks veneering process are not yet fully understood. In particular the study of zirconia behavior at the interface with the veneer remains a ... [more ▼]

OBJECTIVES: The phenomena occurring during zirconia frameworks veneering process are not yet fully understood. In particular the study of zirconia behavior at the interface with the veneer remains a challenge. However this interface has been reported to act on residual stress in the veneering ceramic, which plays a significant role in clinical failures such as chipping. The objective of this study was thus to investigate the veneer-zirconia interface using a recent 3D-analysis tool and to confront these observations to residual stress measurements in the veneering ceramic. METHODS: Two cross-sectioned bilayered disc samples (veneer on zirconia), exhibiting different residual stress profiles in the veneering ceramic, were investigated using 2D and 3D imaging (respectively Scanning Electron Microscopy (SEM) and Focused Ion Beam nanotomography (FIB-nt), associated with chemical analysis by Energy Dispersive X-ray Spectroscopy (EDS). RESULTS: The observations did not reveal any structural change in the bulk of zirconia layer of both samples. However the presence of structural alterations and sub-surface microcracks were highlighted in the first micrometer of zirconia surface, exclusively for the sample exhibiting interior tensile stress in the veneering ceramic. No interdiffusion phenomena were observed. SIGNIFICANCE: FIB nanotomography was proven to be a powerful technique to study the veneer-zirconia interface. The determination of the origin and the nature of zirconia alterations need to be further studied. The results of the present study support the hypothesis that zirconia surface property changes could be involved in the development of tensile stress in the veneering ceramic, increasing the risk of chipping. [less ▲]

Sedimentology and magnetic susceptibility of Mississippian (Tournaisian) carbonate sections in Belgium

in Bulletin of Geosciences (2013), 88(1), 69-82

Magnetic susceptibility (MS) and biostratigraphy have been used to correlate better the reference sections of Belgian Tournaisian, the Rivage road and railway sections and the Gendron-Celles railway ... [more ▼]

Magnetic susceptibility (MS) and biostratigraphy have been used to correlate better the reference sections of Belgian Tournaisian, the Rivage road and railway sections and the Gendron-Celles railway section. These 200 m thick time-equivalent sections are about sixty kilometres apart and belong to two different sedimentation areas: a shallow ramp setting for Rivage (Condroz Sedimentation Area, Hance et al., 2001) and a subsiding area for Gendron (Dinant Sedimentation Area). The sedimentological model shows that both sections are characterized by a bioclastic dominated sedimentation (crinoids-peloids-algae assemblages), interrupted by more argillaceous facies related to rapid sea-level rises (crinoids-brachiopods-bryozoans assemblages). Accommodation was significantly higher in the DSA and allowed the development of Waulsortian buildups during the Ivorian. Variations of magnetic susceptibility (MS) seem to be related to fluctuations in detrital input and carbonate productivity. MS evolution with palaeogeography can be integrated in the Da Silva et al. (2009a) model for the Devonian ramp system: external ramp settings have low carbonate productivity, low water agitation and high MS, whereas more proximal environments are characterized by higher carbonate productivity, higher water agitation and lower MS. Carbonate buildups show the lowest MS and highest productivity. MS curves are in agreement with the 3rd-order sequential interpretation. Lowstand system tracts (LST) show the highest MS values while transgressive system tracts (TST) are characterized by decreasing values and highstand system tracts/ falling stage system tracts (HST/FSST) by the lowest values. [less ▲]

Numerical Exploration of Oscillation Modes in Rapidly Rotating Stars

in Goupil, M.; Belkacem, K.; Neiner, C. (Eds.) et al Studying Stellar Rotation and Convection (2013)

In this chapter, we show that two-dimensional oscillation codes help us to improve our knowledge of the effects of rapid rotation on acoustic (p) and gravity (g) modes. We first discuss how to solve the ... [more ▼]

In this chapter, we show that two-dimensional oscillation codes help us to improve our knowledge of the effects of rapid rotation on acoustic (p) and gravity (g) modes. We first discuss how to solve the full problem of stellar oscillations in rapidly rotating stars by including the effects of the Coriolis force as well as those of the centrifugal distortion. We illustrate the development and the validation of a 2-D code using the Two-dimensional Oscillation Program (TOP) as an example. We then describe what strategies are being developed to explore the p- and g-mode spectra, how effective these methods are, and what intrinsic difficulties they face. In the last part of this chapter, we present results obtained with these techniques. [less ▲]

Determination of Moisture Diffusivity During Drying of Mortar Cement: Experimental and Modeling Study

in International Journal of Energy Engineering (2013), 3(1), 1-6

The aim of this study is the experimental characterization of the behaviour of a mortar during convective drying. We focalise on mortar that has a rate water-cement of 0.5. The drying tests are developed ... [more ▼]

The aim of this study is the experimental characterization of the behaviour of a mortar during convective drying. We focalise on mortar that has a rate water-cement of 0.5. The drying tests are developed in a micro-convective dryer that can use samples weighing from 0 to 8g. The advantage of these experiments is to reproduce the natural conditions that can be found during the treatment of the mortar-atmosphere problems. The response of the drying curve or the drying kinetic depends on the applied drying conditions. So, the temperature of the air varies from 60°C to 130°C, the velocity of the air is changed from 2 m.s-1 to 5 m. s-1and the relative humidity is kept less than 1.7%. The comparison between the experimental results and the proposed analytical solutions of the equation of diffusion represented by Fick’s law, applied for a finite shape, allows determination of the values of the diffusion coefficient. It has a value of 1.71×10-10 m2.s-1 at 60°C, 13.69×10-10 m2.s-1 at 90°C and 16.27×10-10 m2.s-1 at 130°C. Calculation of the activation energy and the D0 constant are also possible. [less ▲]

Quelques considérations sur la préservation de l'authenticité des quartiers résidentiels modernes du nord de Bucarest

in Crisan, Rodica, Franco, Giovanna; Musso, Stefano F. (Eds.) Conservation / Regeneration - The modernist neighborhood (2013)