A higher order Finite Volume resolution method for a system related to the inviscid primitive equations in a complex domain

We construct the cell-centered Finite Volume discretization of the two-dimensional inviscid primitive equations in a domain with topography. To compute the numerical fluxes, the so-called Upwind Scheme (US) and the Central-Upwind Scheme (CUS) are introduced. For the time discretization, we use the classical fourth order Runge–Kutta method. We verify, with our numerical simulations, that the US (or CUS) is a robust first (or second) order scheme, regardless of the shape or size of the topography and without any mesh refinement near the topography.     

LiMSO(4)F (M = Fe, Co and Ni): promising new positive electrode materials through the DFT microscope

A theoretical study of the lithium intercalated LiMSO(4)F and deintercalated MSO(4)F systems, where M = Fe, Co and Ni has been performed within the framework of density functional theory. Beyond predictions of structural evolution and average voltages versus a lithium electrode, we have applied partial density of states and Bader's topological analysis of the electron density to the study of lithium deintercalation. Upon lithium extraction, charge rearrangement occurs for nickel between different d-orbitals, but with little net positive charge gain, while cobalt and iron atoms end up with a clear oxidized state. The participation of oxygen ions in accepting the electron of the lithium is thus enhanced for LiNiSO(4)F. However, this effect does not affect the long-range electrostatic interactions a lot in the lithiated phase, since the valence of all transition metals is very close due to initial lower oxidized state for the Ni atom in the host. It is found that this is not essentially a long-range electrostatic interaction within the lithiated phase but within the host which explains, at least partly, the increase in voltage by passing from Fe to Ni. Our results also shed light upon the possibility of getting an approximate evaluation of the local strain associated with delithiation from the atomic volume evolutions, which are also likely to affect the electrochemical potential.     

Optimization of a one dimensional hypertelescope for a direct imaging in astronomy

We describe an application of nonlinear optimization in interferometric optical astronomy. The aim is to find the relative positions of the output pupils and the modulus of the beams through each pupil of a linear array of telescopes in order to design an instrument capable of imaging exoplanets. The problem is modelized under the form of a semi-infinite nonlinear minimization problem. The model problem is transformed by a simple discretization into a minimization problem with a finite number of constraints, then it is solved by using a minimization solver. Numerical experiments are reported.     

Simple Analysis of Glutathione in Human Colon Carcinoma Cells and Epidermoid Human Larynx Carcinoma Cells by HPLC with Electrochemical Detection

Here, we provide an extremely simple, rapid, direct, sensitive and specific method to quantify, for the first time in human colon carcinoma cells (HT29) and epidermoid human larynx carcinoma cells (HEp-2), the intracellular glutathione (GSH) using an electrochemical detector coupled to a high performance liquid chromatograph (HPLC-ECD). GSH determination in cancer cells are of valuable interest because GSH has been implicated in the development of resistance to several anticancer drugs. Separation of GSH was performed on a Alltima C18 column using a binary pre-mixed mobile phase of methanol-NaH₂PO₄ (10 mM, pH 3.0 with phosphoric acid) (2:98, v/v). GSH was detected with an oxidation potential of +500 mV. The limit of detections was 0.30 pMol and good linearity (r = 0.9988) was found. The intra-day and the inter-day recoveries were 97.1–101.3% and 98.2–101.8% respectively, whereas the accuracies were less than 2.56% and 3.02% respectively. The usefulness of the method was established by subjecting HT29 and HEp-2 cells to an oxidant stress generated by menadione, a substance able to decrease GSH level in cells. The experiments show that the HPLC-ECD method developed could represent an useful alternative to the existing procedures since its simplicity and rapidity.     

Multifunctional Redox Polymers: Electrochrome,Polyelectrolyte, Sensor,Electrode Modifier,Nanoparticle Stabilizer,and Catalyst Template

Simple “click” polycondensation metallopolymers of redox‐robust bis(ethynyl)biferrocene (biFc) and di(azido) poly(ethylene glycol) (PEG400 and PEG1000) were designed for multiple functions including improvement of water solubility and biocompatibility, the introduction of mixed valency and sensing capabilities, and as nanoparticle stabilizers for catalysis.     

A Bennett concentration inequality and its application to suprema of empirical processesUne inégalité de concentration de type Bennett et son application aux maxima de processus empiriques

We introduce new concentration inequalities for functions on product spaces. They allow to obtain a Bennett type deviation bound for suprema of empirical processes indexed by upper bounded functions. The result is an improvement on Rio's version [6] of Talagrand's inequality [7] for equidistributed variables. To cite this article: O. Bousquet, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 495–500.     

Analyse de structures tridimensionnelles inhomogenes quelconques

This paper illustrates the capability of SR3D software to rigorously analyze 3D radiating structures including wires (thin or thick), dielectric parts and finite ground planes. The analysis method is within the class of bound ary element method (bem) and use integral equation formulation (combined field integral equation cfie) to solve electromagnetic scattering problems. It includes a variational approach based on Rumsey reaction concept. The problem is numerically solved with a surface finite element method : surfaces of 3D conducting object and interfaces between dielectric domains are meshed using surface triangular patches. We discuss on the numerical options chosen, the basis functions used, discretization density, and treatment of wires. The last sections emphasize the accuracy of the method on examples for which computed and measured reflection coefficient and radiation patterns are compared.     

Simulation of the performance of a Ka‐band VSAT videoconferencing system with uplink power control and data rate reduction to mitigate atmospheric propagation effects

The purpose of this paper is to evaluate the impact of propagation effects at 20/30 GHz on the performances of the radio interface of a VSAT videoconferencing system and to demonstrate the interest to implement Fade Mitigation Techniques in order to improve the link availability. Specifications and system requirements of the VSAT network are briefly described. System performances of the physical layer are simulated using time‐series data measured with the ESA's OLYMPUS satellite. The simulations enable to implement and optimize Up‐Link Power Control and Data Rate Reduction, and to assess the related link performance improvement. Moreover, the introduction of propagation data sets allows to have a better idea of some system parameters which directly impact on the quality of service such as the switching rate or the link availability that such a system should have when deployed in operational conditions. Copyright © 2002 John Wiley & Sons, Ltd.     

Continuous transition from 3D to 1D confinement observed during the formation of CdSe nanoplatelets

We study the formation of colloidal CdSe nanoplatelets using both tansmission electron microscopy (TEM) and spectroscopic analysis. We show that the platelets form by continuous lateral extension of small (<2 nm) nanocrystal CdSe seeds. The nanoplatelet thickness is fixed by the seed dimension and remains constant during the platelet formation. The nanoplatelet lateral dimensions can be tuned using additional precursor injection. Absorption and fluorescence analysis of the CdSe nanoplatelets as they continuously extend laterally confirms a continuous transition from 3D to 1D confined nanoparticles. The formation of the CdSe platelets is found to be similar for different platelet thicknesses that we control with a precision of one CdSe monolayer.