Domain decomposition methods in a geometrical multiscale domain using finite volume schemes

The heat equation is solved by using a finite volume discretization in a domain that consists of a two-dimensional central node and several one-dimensional outgoing branches. Several interface connection options to match the submodels set on the node and on the branches, with or without continuity, are looked at. For each of them, a monolithic scheme is defined, and existence and uniqueness of the solution is proved. New schemes are deduced, which are obtained through domain decomposition methods in the form of interface systems, with one or two unknowns per interface. A comparative systematic study is carried out from an algebraic and numerical point of view according to the interface conditions: Dirichlet, Neumann, or Robin. An efficient diagonal preconditioning is proposed.     

New Quinoxaline Derivatives as Dual Pim-1/2 Kinase Inhibitors: Design,Synthesis and Biological Evaluation

Proviral integration site for Moloney murine leukemia virus (Pim)-1/2 kinase overexpression has been identified in a variety of hematologic (e.g., multiple myeloma or acute myeloid leukemia (AML)) and solid (e.g., colorectal carcinoma) tumors, playing a key role in cancer progression, metastasis, and drug resistance, and is linked to poor prognosis. These kinases are thus considered interesting targets in oncology. We report herein the design, synthesis, structure–activity relationships (SAR) and in vitro evaluations of new quinoxaline derivatives, acting as dual Pim1/2 inhibitors. Two lead compounds (5c and 5e) were then identified, as potent submicromolar Pim-1 and Pim-2 inhibitors. These molecules were also able to inhibit the growth of the two human cell lines, MV4-11 (AML) and HCT-116 (colorectal carcinoma), expressing high endogenous levels of Pim-1/2 kinases.     

Acoustic Radiation from a Finite Length Cylindrical Shell Excited by an Internal Acoustic Source: Solution Based on a Boundary Element Method and a Matched Asymptotic Expansion

This paper deals with acoustic radiation by a thin elastic shell, closed by two perfectly rigid discs, immersed in water and filled with air. The system is driven by an internal acoustic source. The shell has a length L, is clamped along one of its boundaries and is freely supported along the other boundary. Using the infinite domain Green's function, the radiated acoustic pressure is modeled by a hybrid layer potential (linear combination with nonreal coefficient of a simple layer and a double layer). Using Green's tensor of the in vacuo shell operator, the shell displacement is expressed as the sum of the field generated by the acoustic pressures and that due to boundary sources. Finally, the Green's function of the interior Neumann problem is used to express the acoustic pressure inside the shell in terms of the acoustic source and shell normal displacement: this representation fails for any frequency equal to one of the resonance frequencies of the shell interior. To overcome this, a light fluid approximation, which is allowed because the inner fluid is a gas, is adopted. Around each resonance frequency, an inner approximation is defined which matches the classical outer approximation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Rheological characterization of a solder paste for surface mount applications

Solder pastes used in surface mount soldering techniques (SMT) are very complex suspensions containing high volumes of metallic powder in a carrier fluid. The rheological complexity results largely from the carrier fluid itself, which is a suspension of colloidal particles. In this work, we have characterized the rheological properties of a typical carrier fluid and its solder paste containing 64 vol.% metallic powder. A six-blade vane geometry was used to avoid wall slip and sample fracture. All measurements were carried out following pre-shearing and rest time in order to obtain reproducible results. Steady shear experiments showed that the solder paste was highly shear-thinning and thixotropic. In oscillatory shear, the linear viscoelastic domain was found to be very narrow for both the suspending fluid and the paste. Frequency sweep tests in the linear domain revealed a gel-like structure with a nearly constant G′ for the suspending fluid and a slightly increasing G′ for the solder paste. From creep experiments, a yield stress of about 40 Pa was determined for the suspending fluid at temperatures between 25 and 40°C, and of 100 Pa at 4°C. A much larger yield stress, 480 Pa, was determined for the solder paste at 25°C.     

Uniform limit laws of the logarithm for nonparametric estimators of the regression function in presence of censored data

In this paper, we establish uniform-in-bandwidth limit laws of the logarithm for nonparametric Inverse Probability of Censoring Weighted (I.P.C.W.) estimators of the multivariate regression function under random censorship. A similar result is deduced for estimators of the conditional distribution function. The uniform-in-bandwidth consistency for estimators of the conditional density and the conditional hazard rate functions are also derived from our main result. Moreover, the logarithm laws we establish are shown to yield almost sure simultaneous asymptotic confidence bands for the functions we consider. Examples of confidence bands obtained from simulated data are displayed.      

C 1-generic billiard tables have a dense set of periodic points

We prove that the set of periodic points of a generic C ¹-billiard table is dense in the phase space.     

Prediction of the flow field over an orbiter entering the Mars atmosphere

This paper presents the methodology and the physical models implemented in our computational code to predict the flow field over a Mars Sample Return Orbiter entering a Mars-like atmosphere. Because no validation against flight data or experiments can be done at present, the results obtained here are compared to other computed results for verification purpose. The predicted flow fields show that the chemical species CO and CO₂, that are highly radiative species, are present in a large amount and at high temperature in the shock layer and in the wake of the flow past the orbiter.     

A comparative study of ECNC and CNC suspensions: effect of salt on rheological properties

This paper addresses the effect of monovalent (Na⁺) and divalent (Ca²⁺) ions on the shear viscosity and viscoelastic properties of two different aqueous suspensions of nanoparticles, cellulose nanocrystals (CNCs), and electrosterically stabilized nanocrystals of cellulose (ECNCs). ECNC is similar as CNC, but with carboxylated cellulose chains protruding from both endcaps. The different suspensions were studied in the semi-dilute regime, which corresponded to concentrations ranging from 0.5 to 8 wt% for CNCs and from 0.6 to 9 wt% for ECNCs. As the charges on CNCs are presumably distributed all along the crystal domains and the CNC have a twist in their backbone structure, their suspensions shifted to a cholesteric state as the volume fraction increased while ECNC suspensions did not. This is because the charges on ECNCs are mainly distributed at the endcaps of the particles and the protruding chains expel each other. On the one hand, it was demonstrated that at moderate ionic strength (I = 20 mM), CNC suspensions formed gels even at really low concentrations due to agglomeration. Calcium chloride (CaCl₂) had a greater effect than sodium chloride (NaCl) on both shear and viscoelastic properties due to stronger network formation. On the other hand, ECNCs could withstand much higher ionic strengths than CNCs. NaCl had no effect other than making the ECNC particles precipitate above a concentration of 200 mM, while CaCl₂ made ECNC suspensions turn into gels due to a bridging effect with their carboxylic acid groups at a concentration of [Ca2+] ≈ [COOH]/2.     

Measurement of Total and Unbound Mycophenolic Acid and Its Glucuronide by LC Coupled with MS. Application to a Pharmacokinetic Study of Mycophenolate Mofetil in Patients with Autoimmune Diseases

Liquid chromatography coupled with mass spectrometry for the determination of total and unbound mycophenolic acid and its major metabolite in human plasma has been developed. Sample preparations were based on a fully automated solid-phase extraction process and ultrafiltration. Mass spectrometric data were acquired in a single-ion monitoring method. The analytes and nevirapine (internal standard) were well separated in an isocratic mode over 8 min. Validation study exhibited excellent linearity, with intra- and inter-day precision and accuracy of less than 12%. The assay was successfully applied to the pharmacokinetic study of mycophenolic acid in patients with autoimmune diseases.