A relaxation multiresolution scheme for accelerating realistic two‐phase flows calculations in pipelines

We wish to demonstrate that it is judicious to combine various existing computational techniques that appeared for academic cases in seemingly unrelated areas, namely, semi‐implicit relaxation schemes for hyperbolic systems and adaptive multiresolution algorithms, in order to achieve fast and accurate simulations of realistic two‐phase flows problems in oil transportation. By ‘realistic’ we mean problems that are modelled by partial differential equation (PDE) systems closed by sophisticated thermodynamics and hydrodynamics laws, set out over a terrain‐induced geometry and associated with time‐dependent boundary conditions. Although the combination of these techniques is not a straightforward matter, it is made possible via a careful examination of the objectives of the simulation problem and suitable adaptations of which we shall give the details. Significant benchmarks demonstrate the efficiency of the proposed method. Copyright © 2006 John Wiley & Sons, Ltd.     

UA62784 Is a cytotoxic inhibitor of microtubules, not CENP-E

A recent screen for compounds that selectively targeted pancreatic cancer cells isolated UA62784. We found that UA62784 inhibits microtubule polymerization in?vitro. UA62784 interacts with tubulin dimers ten times more potently than colchicine, vinblastine, or nocodazole. Competition experiments revealed that UA62784 interacts with tubulin at or near the colchicine-binding site. Nanomolar doses of UA62784 promote the accumulation of mammalian cells in mitosis, due to aberrant mitotic spindles, as shown by immunofluorescence and live cell imaging. Treatment of cancerous cell lines with UA62784 is lethal, following activation of apoptosis signaling. By monitoring mitotic spindle perturbations and apoptosis, we found that the effects of UA62784 and of some known microtubule-depolymerizing drugs are additive. Finally, high content screening of H2B-GFP HeLa cells revealed that low doses of UA62784 and vinblastine potentiate each other to inhibit proliferation.     

About de Smit��s question on flatness

Let ${\varphi : A \rightarrow B}$ be a flat morphism of Artin local rings with the same embedding dimension. Denote by ${\mathfrak{m}_A}$ the maximal ideal of A. Bart de Smit asked whether any finite B-module that is A-flat is B-flat. We prove the conjecture in embedding dimension one or two. In embedding dimension n, we prove the conjecture under an additional assumption on ${B/\mathfrak{m}_{A}B}$ .     

Mechanism of YF3 nanoparticle formation in reverse micelles

This article reports an investigation of the mechanism of YF(3) nanoparticle formation in two variants of the reverse microemulsion precipitation method. These two variants involve the addition of F(-), either as a microemulsion or directly as an aqueous solution, to Y(3+) dispersed in nonionic reverse micelles. The two methods yield amorphous and single-crystal nanoparticles, respectively. The kinetics of reagent mixing are studied by (19)F NMR and colorimetric model reactions, and the particle growth is monitored by TEM. Mixing and nucleation are shown to occur within seconds to minutes whereas particle growth continues for 4 to 48 h, depending on the particle type. Moreover, the growth rate remains constant during most of the growth period, indicating that Ostwald ripening is the most probable growth mechanism. The single-emulsion method also produces a minority amorphous population that exhibits significantly different growth kinetics, attributed to a coagulation mechanism. Secondary growth experiments, involving the addition of precursor ions to mature particles, have been conducted to evaluate the relative importance of nucleation and the competitive growth of existing particle populations. The key differences between the two methods reside in the nucleation step. In the case of the classical method, nucleation occurs upon intermicellar collisions and under conditions of comparable concentrations of Y(3+) and F(-). This method generates more numerous stable nuclei and smaller particles. In the single-microemulsion method, nucleation occurs in the presence of excess F(-) through the interaction of Y(3+)-containing micelles with microdroplets of aqueous F(-). These conditions lead to the formation of crystalline particles and a wider size distribution of unstable nuclei.     

Well-Posedness and Singular Limit of a Semilinear Hyperbolic Relaxation System with a Two-Scale Discontinuous Relaxation Rate

Nonlinear hyperbolic systems with relaxations may encounter different scales of relaxation time, which is a prototype multiscale phenomenon that arises in many applications. In such a problem the relaxation time is of O(1) in part of the domain and very small in the remaining domain in which the solution can be approximated by the zero relaxation limit which can be solved numerically much more efficiently. For the Jin–Xin relaxation system in such a two-scale setting, we establish its wellposedness and singular limit as the (smaller) relaxation time goes to zero. The limit is a multiscale coupling problem which couples the original Jin–Xin system on the domain when the relaxation time is O(1) with its relaxation limit in the other domain through interface conditions which can be derived by matched interface layer analysis.As a result, we also establish the well-posedness and regularity (such as boundedness in sup norm with bounded total variation and L ¹-contraction) of the coupling problem, thus providing a rigorous mathematical foundation, in the general nonlinear setting, to the multiscale domain decomposition method for this two-scale problem originally proposed in Jin et al. in Math. Comp. 82, 749–779, 2013.     

MALDI-TOF-MS Directly Combined with TLC: A Review of the Current State

Thin-layer chromatography (TLC) is a widely used, fast and inexpensive method for separating complex mixtures. Unfortunately, the quality of achievable separation represents only one side. An additional problem is the unambiguous assignment of the obtained spots to defined compounds. Clear identification of spots is often not possible by common staining methods and comparison with a known reference compound. Therefore, further analytical techniques are mostly required for further structural elucidation. Mass spectrometry (MS) is a suitable method due to its high sensitivity. In particular, matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) MS is a modern soft-ionization technique that may be easily combined with TLC. This review summarizes the so far available knowledge about direct TLC–MALDI combination and gives an overview about different molecule classes that have already been successfully analyzed by this approach. This review critically summarizes the capabilities and limitations of the direct MALDI–TLC combination and highlights in particular the problems related to sample preparation and instrumentation.     

Blood Compatibility of Multilayered Polyelectrolyte Films Containing Immobilized Gold Nanoparticles

Surface material functionalization including layer‐by‐layer (LbL) polyelectrolyte films with incorporated nanoparticles is a growing field with a wide range of biomedical applications: drug reservoirs, medical devices, or tissue engineering. In parallel, gold nanoparticles (AuNPs) can be grafted by drugs and sensitive molecules using simple protocols. This study shows that AuNP behavior is modified when they are entrapped into three partner LbL films in comparison to the colloidal solution. A polycationic (polyallylamine hydrochloride (PAH)) and a polyanionic (polyacrylic acid (PAA)) polymer is used to build films based on three cycles ((PAH/AuNP/PAA)₃). To investigate the interaction with biomolecules and cells, three different films are developed changing the outer layer (either PAH or AuNP or PAA) with the same number of AuNP deposit. The best biocompatibility is observed with a polyacrylic acid outer layer. Due to the high capacity of drug grafting on gold nanoparticles, the results seem promising for the development of nanostructured biomedical devices.     

Testing statistical significance of multivariate time series analysis techniques for epileptic seizure prediction

Nonlinear time series analysis techniques have been proposed to detect changes in the electroencephalography dynamics prior to epileptic seizures. Their applicability in practice to predict seizure onsets is hampered by the present lack of generally accepted standards to assess their performance. We propose an analytic approach to judge the prediction performance of multivariate seizure prediction methods. Statistical tests are introduced to assess patient individual results, taking into account that prediction methods are applied to multiple time series and several seizures. Their performance is illustrated utilizing a bivariate seizure prediction method based on synchronization theory.     

A priori and a posteriori analysis of finite volume discretizations of Darcy’s equations

Summary This paper is devoted to the numerical analysis of some finite volume discretizations of Darcys equations. We propose two finite volume schemes on unstructured meshes and prove their equivalence with either conforming or nonconforming finite element discrete problems. This leads to optimal a priori error estimates. In view of mesh adaptivity, we exhibit residual type error indicators and prove estimates which allow to compare them with the error in a very accurate way. Mathematics Subject Classification (2000):65G99, 65M06, 65M15, 65M60, 65P05This work was partially supported by Contract C03127/AEE2714 with the Laboratoire National dHydraulique of the Division Recherche et Développement of Électricité de France. We thank B. Gest and her research group for very interesting discussions on this subject.     

Taylor dispersion analysis of metallic-based nanoparticles – A short review

Taylor dispersion analysis (TDA) is an interesting tool for nanoparticle (NP) size determination, feasible using simple capillary electrophoresis apparatus. Based upon the radial diffusion of analytes upon a laminar stream, the diffusion coefficient of species is easily estimable. Moreover, TDA is generally more adequate than conventional dynamic light scattering methodologies as it is less dependent on the polydispersity of the sample, leading to accurate measurement and reliable results. This review provides every paper mentioning the use of TDA for metallic-based NPs size determination. Diverse strategies for the detection of metallic NPs (like UV–visible and inductively coupled plasma–mass spectrometry – ICP–MS – for instance) and interpretation of the Taylorgrams are discussed. Based upon the literature, advices on future prospects are also indicated, especially for the comparison of TDA results with other classical techniques.