Ab initio finite field (hyper)polarizability computations on stoichiometric gallium arsenide clusters GanAsn (n=2-9)

We report reliable ab initio finite field (hyper)polarizability values at Hartree-Fock and second order Moller-Plesset perturbation theory (MP2) levels of theory for different geometrical configurations of small gallium arsenide clusters Ga(n)As(n) with n=2-5. We relied on all-electron basis sets and pseudopotentials suitable for (hyper)polarizability calculations. In each case, we used structures that have been established in the literature after we optimized their geometries at B3LYP/cc-pVTZ-PP level of theory. Our results suggest that the first order hyperpolarizability (beta) is much more sensitive to the special geometric features than the second order hyperpolarizability (gamma). For the most stable configurations up to ten atoms the second order hyperpolarizability at MP2 level of theory varies between 15 x 10(4) and 32 x 10(4) e(4)a0 (4)Eh(-3). In addition, we examined the polarizability per atom evolution versus the cluster size for Ga(n)As(n) with n=2-9. Our work extends earlier theoretical studies which were limited to eight atoms and exposes that the polarizability/atom of the most stable stoichiometric configurations up to Ga(9)As(9) continues the monotonic downward trend with increasing size. Lastly, from the methodological point of view, our analysis shows that apart from polarizabilities, augmented pseudopotentials yield reliable first and second hyperpolarizability values as well.     

Analysis of plasma protein adsorption onto PEGylated nanoparticles by complementary methods: 2-DE, CE and Protein Lab-on-chip system

The biodistribution of colloidal carriers after their administration in vivo depends on the adsorption of some plasma proteins and apolipoproteins on their surface. Poly(methoxypolyethyleneglycol cyanoacrylate-co-hexadecylcyanoacrylate) (PEG-PHDCA) nanoparticles have demonstrated their capacity to cross the blood-brain barrier (BBB) by a mechanism of endocytosis. In order to clarify this mechanism at the molecular level, proteins and especially apolipoproteins adsorbed at the surface of PEG-PHDCA nanoparticles were analyzed by complementary methods such as CE and Protein Lab-on-chip in comparison with 2-D PAGE as a method of reference. Thus, the ability of those methodologies to identify and quantify human and rat plasma protein adsorption onto PEG-PHDCA nanoparticles and conventional PHDCA nanoparticles was evaluated. The lower adsorption of proteins onto PEG-PHDCA nanoparticles comparatively to PHDCA nanoparticles was evidenced by 2-D PAGE and Protein Lab-on-chip methods. CE allowed the quantification of adsorbed proteins without the requirement of a desorption procedure but failed, in this context, to analyze complex mixtures of proteins. The Protein Lab-on-chip method appeared to be very useful to follow the kinetic of protein adsorption from serum onto nanoparticles; it was complementary to 2-D PAGE which allowed the identification (with a relative quantification) of the adsorbed proteins. The overall results suggest the implication of the apolipoprotein E in the mechanism of passage of PEG-PHDCA nanoparticles through the BBB.     

A New Hybrid Possibilistic-Probabilistic Decision-Making Scheme for Classification

Uncertainty is at the heart of decision-making processes in most real-world applications. Uncertainty can be broadly categorized into two types: aleatory and epistemic. Aleatory uncertainty describes the variability in the physical system where sensors provide information (hard) of a probabilistic type. Epistemic uncertainty appears when the information is incomplete or vague such as judgments or human expert appreciations in linguistic form. Linguistic information (soft) typically introduces a possibilistic type of uncertainty. This paper is concerned with the problem of classification where the available information, concerning the observed features, may be of a probabilistic nature for some features, and of a possibilistic nature for some others. In this configuration, most encountered studies transform one of the two information types into the other form, and then apply either classical Bayesian-based or possibilistic-based decision-making criteria. In this paper, a new hybrid decision-making scheme is proposed for classification when hard and soft information sources are present. A new Possibilistic Maximum Likelihood (PML) criterion is introduced to improve classification rates compared to a classical approach using only information from hard sources. The proposed PML allows to jointly exploit both probabilistic and possibilistic sources within the same probabilistic decision-making framework, without imposing to convert the possibilistic sources into probabilistic ones, and vice versa.     

L'équation de Navier–Stokes avec mémoire et le transfert de quantité de mouvement dans un milieu poreuxThe Navier–Stokes equation with memory,and momentum transfer in a porous medium

This paper is concerned with the momentum transfer in a porous medium. The equations for the continuous equivalent medium are written by the averaging method but the closure is obtained using an extended thermodynamics. The resulting model corresponds to the Navier–Stokes equation, in which the force exerted by the solid matrix on the fluid satisfies of first order differential equation. This Navier–Stokes equation model with memory generalises the Darcy model with an integro-differential term. To cite this article: O. Séro-Guillaume, D. Calogine, C. R. Mecanique 330 (2002) 383–389.     

Living ROMP Synthesis and Redox Properties of Diblock Ferrocene/Cobalticenium Copolymers

Using the third‐generation Grubbs catalyst, the living ring‐opening metathesis polymerization of ferrocene/cobalticenium copolymers is conducted with theoretical numbers of 25 monomer units for each block, and their redox and electrochemical properties allow using the Bard–Anson electrochemical method to determine the number of metallocenyl units in each block.

     

Integrated all‐optical switch with 10 ps time resolution enabled by ALD

Abstract The potential of GaAs‐based photonic crystals for fast all‐optical switching in the telecom spectral range is exploited by controlling the surface recombination and, thereby, the carrier relaxation dynamics. The structure is entirely coated with a layer of aluminium oxide using atomic layer deposition. This results in a carrier lifetime of about 10 ps, as determined by spectrally resolved pump–probe measurements. We show that the nonlinear response of the resonator is optimized when it is excited with a few‐picoseconds pulse. This dynamics is perfectly captured by our model accounting for the carrier diffusion with an impulse response function. Moreover, the suppression of photo‐induced oxidation is revealed to be crucial to demonstrate all‐optical operation at GHz rates with average coupled pump power of 0.5 mW (hence 100 fJ/bit). The switching window is 12 ps wide (1/e), as resolved by homodyne pump–probe measurements. The devices respond to a sequence of closely spaced pump pulses demonstrating a gating window close to 10 ps, with a contrast as high as 7 dB.

     

Quantization and Motion Law for Ginzburg–Landau Vortices

We study the vortex trajectories for the two-dimensional complex parabolic Ginzburg–Landau equation without a well-preparedness assumption. We prove that the trajectory set is rectifiable, and satisfies a weak motion law. In the case of degree  ±  1 vortices, the motion law is satisfied in the classical sense. Moreover, dissipation occurs only at a finite number of times. Away from these times, possible collisions and splittings of vortices are constrained by algebraic equations involving their topological degrees. Quantization properties of the energy and potential densities play a central role in the proofs.     

Effects of Oblique Inflow in Vortex-Induced Vibrations

We investigate the validity of the independence principle for fixed yawed circular cylinders and free yawed circular rigid cylinders subject to vortex-induced vibrations (VIV) at subcritical Reynolds number using direct numerical simulation (DNS). We compare forces on the cylinder and cylinder responses for different angles of yaw and reduced velocities, and investigate the value of the critical angle of yaw. We also present flow visualizations and examine flow structures corresponding to different angles of yaw and reduced velocities.     

Anisotropic Gold Nanoparticles: Synthesis,Properties, Applications,and Toxicity

Anisotropic gold nanoparticles (AuNPs) have attracted the interest of scientists for over a century, but research in this field has considerably accelerated since 2000 with the synthesis of numerous 1D, 2D, and 3D shapes as well as hollow AuNP structures. The anisotropy of these nonspherical, hollow, and nanoshell AuNP structures is the source of the plasmon absorption in the visible region as well as in the near‐infrared (NIR) region. This NIR absorption is especially sensitive to the AuNP shape and medium and can be shifted towards the part of the NIR region in which living tissue shows minimum absorption. This has led to crucial applications in medical diagnostics and therapy (“theranostics”), especially with Au nanoshells, nanorods, hollow nanospheres, and nanocubes. In addition, Au nanowires (AuNWs) can be synthesized with longitudinal dimensions of several tens of micrometers and can serve as plasmon waveguides for sophisticated optical devices. The application of anisotropic AuNPs has rapidly spread to optical, biomedical, and catalytic areas. In this Review, a brief historical survey is given, followed by a summary of the synthetic modes, variety of shapes, applications, and toxicity issues of this fast‐growing class of nanomaterials.