Designing and evaluating an energy efficient Cloud

Cloud infrastructures have recently become a center of attention. They can support dynamic operational infrastructures adapted to the requirements of distributed applications. As large-scale distributed systems reach enormous sizes in terms of equipment, the energy consumption issue becomes one of the main challenges for large-scale integration. Like any other large-scale distributed system, Clouds face an increasing demand in energy. In this paper, we explore the energy issue by analyzing how much energy virtualized environments cost. We provide an energy-efficient framework dedicated to Cloud architectures and we validate it through different experimentations on a modern multicore platform. We show on a realistic example that our infrastructure could save 25% of the Cloud nodes’ electrical consumption.     

Methane calibration burner and C‐factor determination with cone calorimeter – validation of the standardized calibration protocol

The cone calorimeter is one of the major fire tests. In its reference standard ISO 5660‐1, the apparatus (and especially a characteristic of its orifice plate mass flow meter, called C‐Factor) is calibrated using a methane burner set at 5 kW. However, measurements performed in end‐use are in the range 1–10 kW. In addition, standard proposes to check linearity at 1 and 3 kW, which means in the lowest part of the range. This communication establishes the validation of the linearity on the whole range and determines the optimal condition for C‐factor determination. It justifies the technical choices of the standard. Copyright © 2014 John Wiley & Sons, Ltd.     

Sequential vapor sorption of additional penetrants in preswollen polymers

Uptake and removal of a second penetrant in polymer samples preexposed to another vapor dictate many industrially important processes. Both the kinetics and equilibrium sorption can be strongly affected by the presence of the first permeant in the polymeric matrices. A novel experimental setup was constructed to study penetrant uptake in sequence. Sorption of the second vapor took place while the partial vapor pressure of the first vapor was maintained, so that diffusion into the preswollen polymer approximated transport in a pseudobinary system. Polybutylene was chosen in this work to illustrate the capability of this versatile experimental system. Both the rate of diffusion and equilibrium sorption of the second vapor were found to depend on the prevailing composition of the preswollen polymer for all penetrant pairs studied.     

Structural evolution at short and medium range distances during crystallization of a P2O5-Li2O-Al2O3-SiO2 glass

Li₂O-Al₂O₃-SiO₂ (LAS) glass-ceramics have important industrial applications and bulk nucleation is usually achieved by using nucleating agents. In particular, P₂O₅ is an efficient agent in glasses containing a low level of Al₂O₃ but its role in the first stages of nucleation is not well established. In this study, we combine structural investigations from local to mesoscales to describe the structural evolution during crystallization of LAS glass-ceramics. Local environment is probed using ²⁹Si and ³¹P MAS-NMR, indicating organization of P in poorly crystallized Li₃PO₄ species prior to any crystallization. To better understand the detailed nanoscale changes of the glass structure, ³¹P-³¹P DQ-DRENAR homonuclear correlation experiments have been carried out, revealing the gradual segregation of P atoms associated with the formation of disordered Li₃PO₄. Small-angle neutron scattering data also show the apparition of nanoscale heterogeneities associated with Li₃PO₄ species upon heating treatments and allow the determination of their average sizes. These new structural information enhance our understanding of the role of P in nucleation mechanisms. Nucleation is initiated by gradual change in P environment implying P segregation upon heating treatments, forming disordered Li₃PO₄ heterogeneities. The segregation of P atoms enables the precipitation of meta- and disilicate phases.     

The Esterase PfeE,the Achilles’ Heel in the Battle for Iron between Pseudomonas aeruginosa and Escherichia coli

Bacteria access iron, a key nutrient, by producing siderophores or using siderophores produced by other microorganisms. The pathogen Pseudomonas aeruginosa produces two siderophores but is also able to pirate enterobactin (ENT), the siderophore produced by Escherichia coli. ENT-Fe complexes are imported across the outer membrane of P. aeruginosa by the two outer membrane transporters PfeA and PirA. Iron is released from ENT in the P. aeruginosa periplasm by hydrolysis of ENT by the esterase PfeE. We show here that pfeE gene deletion renders P. aeruginosa unable to grow in the presence of ENT because it is unable to access iron via this siderophore. Two-species co-cultures under iron-restricted conditions show that P. aeruginosa strongly represses the growth of E. coli as long it is able to produce its own siderophores. Both strains are present in similar proportions in the culture as long as the siderophore-deficient P. aeruginosa strain is able to use ENT produced by E. coli to access iron. If pfeE is deleted, E. coli has the upper hand in the culture and P. aeruginosa growth is repressed. Overall, these data show that PfeE is the Achilles’ heel of P. aeruginosa in communities with bacteria producing ENT.     

Microcellular foaming of poly(lactic acid) branched with food-grade chain extenders

This study evaluated the effectiveness and efficiency of two food-grade multifunctional epoxies chain extenders (CE) in branching PLA and improving its foamability. Both CE grades were effective in branching PLA causing increased end mixing torque, shear, elongational viscosities, molecular weight but decreased crystallinity of poly(lactic acid) (PLA) with CE content, due to chain entanglements. CE with low epoxy equivalent weight (EEW) was more efficient than the counterpart with high EEW due to its high reactivity. Neat PLA foams showed poor cell morphology with areas without nucleated cells and had a low expansion, owing to its low elongational viscosity. By contrast, there was a considerable change in the morphology of the PLA foam structure caused by its branching. Chain-extended PLA foams had uniform cell morphology with a high void fraction (up to ~85%) and expansion ratio (an eightfold expansion over unfoamed PLA) due to their high elongational viscosities, suggesting that melt properties of branched PLA were appropriate for optimum cell growth and stabilization during foaming. Overall, CE with low EEW was the most effective grade and 0.25% the optimum content that provided appropriate melt viscosity to produce PLA foams with a homogeneous structure, fine cells, high void fraction, high volume expansion ratio, and cell-population density.     

Chalcogenide Glasses for Infrared Photonics

The last advances in the synthesis and shaping techniques of chalcogenide glasses suitable for infrared photonics are reported. Ball milling combined with spark plasma sintering allows the preparation of bulk chalcogenide glasses at lower temperature and at lower cost. Microstructuring of optical fibers results in enhanced nonlinear properties leading to the demonstration of low-threshold Brillouin laser at 1.55 μm, all-optical wavelength conversion and time-domain demultiplexing with a 170 Gb/s rate, and supercontinuum between 1.5 and 2.8 μm. The potential of integrated waveguides for functions such as near-IR sensing, mid-IR injection, and (bio)-chemical functionalization is shown.     

Nanocomposite piezoelectric films of P(VDF‐TrFE)/LiNbO3

Piezoelectric films were prepared by incorporation of lithium niobate (LiNbO₃) nanoparticles into copolymer of vinylidene difluoride and trifluoroethylene. Nanoparticles of LiNbO₃ with ferroelectric phase were successfully synthesized and dispersed homogenously by ultrasonication in the copolymer matrix without any surfactant or surface functionalization. The nanocomposites were fully characterized by electronic microscopy, X‐ray diffraction, differential scanning calorimetry, dynamical mechanical analysis, and piezometer. Surprisingly, the copolymer matrix crystallinity and morphology were not affected by the incorporation of nanoparticles. Therefore the nanocomposites remained good mechanicals properties and high ferroelectricity coupled to nonlinear optical activity thanks to the noncentro symmetric space group of lithium niobate. This could be a novel approach to develop new multifunctional materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013