Sol–gel synthesis and sintering of submicronic copper molybdate (α-CuMoO4) powders

A sol–gel method was proposed to prepare copper II molybdate α-CuMoO₄ powders. A gel was first obtained via the polymerizable complex method, using citric acid as complexing and polymerizing agent, dried at 120 °C and decomposed at 300 °C. A calcination in the temperature range 400–500 °C for 2 h led to the pure phase α-CuMoO₄. The different powders obtained were characterized by X ray diffraction analysis and by transmission (TEM) and scanning (SEM) electron microscopies.     

Low power options for 32 nm always-on SRAM architecture

The SRAM 6T bit-cell suffers many limitations in advanced technology nodes among which variability effects. Various alternatives have been experimented and the paper focuses on the 5T-Portless bit-cell. Read and write operations are operated by varying voltage conditions. Literature regarding 32 nm CMOS for Portless SRAM has been reviewed and improvements are presented. The bit-cells are arranged in matrix to permit a current-mode read operation as opposed to voltage-based sensing techniques. Thus safety and stability of the bit-cell operation is established without constraints on memory periphery. The current-mode operation enables a significant gain in dynamic power consumption beneficial to always-on memories. The paper presents different existing solutions to limit the power consumption and their limitations in thin CMOS technologies. The portless bit-cell is presented as a low power architecture alternative to 6T-SRAM. A matrix test-chip is currently under fabrication in bulk CMOS 32 nm.     

Isolation of the MNN9 gene of Yarrowia lipolytica (YlMNN9) and phenotype analysis of a mutant ylmnn9 Delta strain

In this work we describe the isolation of the Yarrowia lipolytica homologue of Saccharomyces cerevisiae MNN9 gene, which we have named YlMNN9, and the phenotype analysis of a Y. lipolytica strain containing the disrupted YlMNN9 allele. YlMNN9 was cloned using degenerate consensus oligonucleotides to generate specific probes that were in turn used to screen mini-gene libraries. The gene is defined by a 1014 bp ORF predicted to encode a protein 337 amino acids long that shares significant homology with the Mnn9ps of S. cerevisiae, Candida albicans and Hansenula polymorpha, including a putative N-terminal transmembrane domain. Disruption of YlMNN9 leads to phenotypes such as resistance to sodium orthovanadate and sensitivity to hygromycin B, compatible with a glycosylation defect, and hypersensitivity to Calcofluor white, Congo red or zymolyase, characteristic of cell wall defects. Analysis of cell wall proteins present in beta-mercaptoethanol and zymolyase extracts showed significant differences between the parental and the ylmnn9 Delta strain. These results suggest that, as has been the case with the mnn9 strain of S. cerevisiae, the ylmnn9 Delta strain we present in this work, could be used to study the cell wall proteins of Y. lipolytica and how they are organized into the cell wall.     

Regional Gradient Stabilization of Semilinear Distributed Systems

This paper deals with regional stabilization of the gradient of semilinear distributed system evolving on a spatial domain Ω. It consists in studying the asymptotic behavior of gradient of such a system in a subregion ω of Ω. Then we characterize gradient stabilizing controls, and the one that stabilizes the gradient on ω and minimizes a given performance cost. The developed results are successfully illustrated by simulations.     

Linear stability analysis of mixed convection flow in a horizontal channel filled with nanofluids

The convective instability driven by buoyancy in the Poiseuille–Rayleigh–Bénard flow through two infinite parallel horizontal plates filled with nanofluids is investigated using linear stability analysis. We considered water‐based nanofluids with different volume fractions of aluminum ( $\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$) and silver ( $\mathrm{A}\mathrm{g}$) nanoparticles. A spectral collocation method founded on Chebyshev polynomials is implemented and the obtained algebraic eigenvalue problem is solved. In this study, we have numerically determined the critical Rayleigh number of the onset of longitudinal and transversal rolls and the results are represented in the form of marginal stability curves. Critical wave numbers that describe the size of convective cells in the flow are also presented, analyzed, and compared with those of the Poiseuille–Rayleigh–Bénard flow without nanoparticles. The effects of the type and nanoparticle volume fractions on the onset of both longitudinal and transversal rolls are investigated.     

Theory of anisotropic oxygen polarizability in the tetragonal phase of BaTiO3

Anisotropic oxygen polarizability in the tetragonal phase of BaTiO³, is discussed taking into account of dipole-dipole interaction due to the electronic polarization and the lattice deformation. In this microscopic model, we have assumed that the dominant source of the optical properties is the anisotropy of the oxygen polarizability, particularly the contribution of the oxygen O_z. It is found that the calculated results are in good agreement with the experimental data.     

Infrared, Raman, and Electron Spin Resonance Studies of Vitreous Alkaline Tungsten Phosphates and Related Glasses

Ternary phosphates are found to vitrify within large domains of compositions inside the phase diagrams P₂O₅–WO₃–A₂O (A = Li, Na). Structural approach of the highly modified glasses P₂O₅–A₂MoO₄–A₂O (M = Mo,W) was investigated using various spectroscopic techniques such as infrared, Raman, and electron spin resonance (ESR). These glasses were found to contain MO₆octahedra, MO₄tetrahedra, M₂O₇dimers, PO₄tetrahedra, and also P₂O₇or metaphosphate chains, depending on the composition considered. As shown in earlier studies, the glass network is progressively depolymerized as the content of A₂O increases. ESR experiments were conducted on both X-ray irradiated and unirradiated samples. Unirradiated glasses exhibit two ESR signals attributed to W⁵⁺ and Mo⁵⁺ centers that are octahedrally coordinated. Irradiation of these glasses induces new paramagnetic centers ascribed to the phosphorus–oxygen–hole–center and peroxy radicals. The M⁵⁺ concentration depends strongly on the sample composition and temperature. ESR parameters are determined using a computer simulation approach adapted for vitreous materials.     

Explicit calculation of smoothed sensitivity coefficients for linear problems

A technique of explicit calculation of sensitivity coefficients based on the approximation of the retrieved function by a linear combination of trial functions of compact support is presented. The method is applicable to steady state and transient linear inverse problems where unknown distributions of boundary fluxes, temperatures, initial conditions or source terms are retrieved. The sensitivity coefficients are obtained by solving a sequence of boundary value problems with boundary conditions and source term being homogeneous except for one term. This inhomogeneous term is taken as subsequent trial functions. Depending on the type of the retrieved function, it may appear on boundary conditions (Dirichlet or Neumann), initial conditions or the source term. Commercial software and analytic techniques can be used to solve this sequence of boundary value problems producing the required sensitivity coefficients. The choice of the approximating functions guarantees a filtration of the high frequency errors. Several numerical examples are included where the sensitivity coefficients are used to retrieve the unknown values of boundary fluxes in transient state and volumetric sources. Analytic, boundary‐element and finite‐element techniques are employed in the study. Copyright © 2003 John Wiley & Sons, Ltd.