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This work aimed at comparing and modelling the kinetics of the free radical grafting of maleic anhydride onto polypropylene (PP) in the solid state with and without supercritical CO 2 (scCO 2 ). The kinetics of the decomposition of dicumyl peroxide (DCP) in scCO 2 and in N 2 was first studied. The one in scCO 2 could be described by k d =1.32 × 10 14 × exp(-139.3 kJ mol -1 /RT). Without scCO 2 the overall grafting reaction rate was controlled, at least partly, by diffusion whereas with scCO 2 it was controlled mainly by the grafting reaction itself. Based on the experimental results, the following general kinetic model for the free radical grafting in scCO 2 was developed: R g =3.35× 10 12 ×exp(-114.5 kJ mol -1 /RT) [I] 0.99 [M] 0.97 (mol L -1 s -1 ).

International audience; This work aimed at studying the efficiency of the use of supercritical carbon dioxide (scCO(2)) as a swelling agent to disperse sodium benzoate (NaBz), a nucleating agent, in polypropylene (PP), on the one hand; and the crystallization behavior of the resulting PP, on the other hand. Under scCO(2), the NaBz was uniformly dispersed in the PP at a nanometer scale. The use of ethanol or acetone as a cosolvent further increased its state of dispersion and its mass uptake in the PP. Isothermal and nonisothermal crystallization kinetics indicated that the PP with the NaBz being dispersed in it under scCO(2) had a much higher crystallization rate than that of the pure PP or the PP with the NaBz being dispersed in it by a conventional melt compounding process. The size of the PP crystallites was also much smaller when the NaBz was dispersed at a nanometer scale

The unique geometry of screw extruders allows handling very viscous media; thus, they can be used as continuous reactors to conduct polymerization reactions without using any solvents. This is call...

Para-fluoro-thiol reaction (PFTR) was applied to poly(2,3,4,5,6-pentafluorostyrene) (PPFS) with mercaptopropionic acid (MPA), resulting in a library of carboxylated-PPFS copolymers (PPFS-MPA) differing in their chemical composition. The ability of these COOH-containing derivatives to develop H-bonds with poly(4-vinyl pyridine) (P4VP) in solvent solution was investigated, and it was shown that the extent of the H-bonded complexes was closely influenced by the degree of PPFS modification and by the nature of solvent. Subsequently, the Layer by Layer stepwise deposition of P4VP and PPFS-MPA was achieved from various deposition solvents. It was demonstrated that the use of DMF as solvent does not allow for the formation of LbL films, due to its competitive H-bond acceptor character. In contrary, when solvents such as CHCl3 and MEK are respectively utilized for P4VP and PPFS-MPA, thick (P4VP/PPFS-MPA)-based LbL films constituted of interpenetrated layers are obtained and the topography is smooth and rather featureless. The use of ethanol as deposition solvent for both P4VP and PPFS-MPA leads to very thin films made of well-stratified polymer layers, with a nodular and patchy surface morphology.

Pickering Interfacial Catalysts (PIC) has emerged as a powerful concept for designing multiphasic reactions between immiscible reagents using heterogeneous catalysts. Nonetheless, systematic studies addressing the influence of the particle self-assembly on the catalytic properties are scarce. To fill this gap, here we studied the effect of the particle size and surface roughness of catalytic nanoparticles on the reactivity of non-aqueous immiscible systems in the presence of Pickering emulsions. To this aim, we prepared a library of amphiphilic silica nanoparticles with the same surface properties and bearing catalytically active acid centers, but showing variable particle sizes in the range 90-460 nm and surface roughness. The nanoparticles were characterized in detail using different techniques, including acid-base titration, TGA, TEM and DLS. The silicas were tested in the biphasic acetalization reaction of dodecanal and ethylene glycol. The catalyst productivity was enhanced for smaller sized nanoparticles (

The amorphous Co-Ce binary metal oxides Co1-yCeyOx prepared by the photochemical metal–organic deposition (PMOD) method is developed as high performance electrocatalysts for oxygen evolution reaction (OER). The influence of Ce content on the OER activity is investigated in terms of geometric and electronic factors. Ce can remarkably enhance the OER activity of CoOx due to the synergistic effect of surface area, Co3+ content, and metal-OH bond strength when the content of Ce is less than 60%. Co0.9Ce0.1Ox supported on fluorine-doped tin oxide (FTO) coated glass substrate shows overpotential of 320 (2) mV at 10 mA cm−2 in 1 M KOH solution. The OER mechanism exploration reveals that the rate determining step changes with the Ce content due to the variation of metal-OH bond strength. This work sheds light on the design of high-performance yet cost-effective OER catalysts.

Ce substituted Nd2Fe14B (2:14:1)-type permanent magnets have shown increasing potential in the applications due to their high properties/cost ratio. However, the element segregation and phase separation in the Ce substituted magnets have not been fully understood yet. In this work, (Nd1−xCex)25Fe40Co20Al4B11 alloys with high coercivities were prepared by copper mold casting. Based on detailed microstructure and composition analysis, the segregation of rare earth (RE) elements was observed in the as-cast alloys. Nd element prefers to enter into the 2:14:1 phase and the Ce element enter into the 1:2 phase. The existence of the 1:2 phase can promote the element segregation. The alloy shows an abnormal increase of coercivity from 641 kA/m for x = 0.2 to 863 kA/m for x = 0.3. This increase could be attributed to the phase separation of the 2:14:1 phase, which has been confirmed by the microstructural characterization. The present data provides useful information for exploring Ce-containing Nd-Fe-B magnets.

International audience; A distinctive strategy for entrainer recycling is proposed in this work for acetic acid (AA) dehydration by extractive distillation by using N methyl acetamide (NMA). The use of standard entrainers such as DMF or DMSO has the main drawback of forming an azeotrope with acetic acid. However, the vapour liquid equilibrium AA – NMA exhibits a tangential pinch point at NMA end composition. The new strategy rises from the thermodynamic analysis of the ternary diagram that which involves no azeotrope. As a result, acetic acid with high purity can be obtained by the recycling of the entrainer with a relaxed constraint in its purity. Optimization studies are discussed by using two approaches: two-step optimization method with Sequential Quadratic Programming (TSOM case) and the multi-objective genetic algorithm. The multi-objective genetic algorithm allowed the computation of the optimal acetic acid dehydration with an impurity of 3% in the recycled entrainer. Significant cost savings are achieved thanks to the optimization of both columns together. Energy consumption is reduced by 12.8% and 56.9% whereas TAC is saved by 28.4% and 56.3% compared with optimal case TSOM (impurity content 1%) and a published “Case Ref” (impurity content 0.01%), respectively.

International audience; A series of 1-aryliminoethylpyridine ligands (L1―L3) was synthesized by condensation of 2-acetylpyridine with 1-aminonaphthalene, 2-aminoanthracene or 1-aminopyrene, respectively. Reaction with nickel dichloride afforded the corresponding nickel (II) chloride complexes (Ni1-Ni3). All compounds were fully characterized and the molecular structures of Ni1 and Ni3 are reported. Upon activation with methylaluminoxane (MAO), all nickel complexes exhibit high activities for ethylene polymerization, producing waxes of low molecular weight and narrow polydispersity. The presence of multi-walled carbon nanotubes (MWCNTs) or few layer graphene (FLG) in the catalytic medium can lead to an increase of productivity associated to a modification of the polymer structure.

The solubility of hydrogen (H2), ethylene (C2H4), 1-hexene (C6H12), and the mixture of C2H4/1-C6H12 in semicrystalline polyethylene (PE) films is measured using an intelligent gravimetric analyzer (IGA) in combination with prediction equations. For the pure-component sorption in PE, the solubility of C2H4 and 1-C6H12 decreases with the temperature, while that of H2 exhibits an opposite variation tendency in the temperature range under test. For the C2H4/1-C6H12 mixture, the co-solubility is almost 10% smaller than the sum of the pure-component solubility. 1-C6H12 acts as a co-solvent and C2H4 an antisolvent. Moreover, good consistency has been achieved between the measured data and the prediction results from the Sanchez-Lacombe EOS model, demonstrating the reliability of the measurement approach employed in this work. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 134, 44507.

In the solar wind, magnetic field power spectra usually show several power-laws. In this paper, magnetic field data from the Cluster mission during an undisturbed interval of slow solar wind is analyzed at 0.28Hz, near the spectral break point between the ion inertial and dissipation/dispersion ranges. Assuming Taylor's frozen-in condition, it corresponds to a proton kinetic scale of $kv_A/\Omega_p \sim 0.38$, where $v_A$ and $\Omega_p$ are the Alfv\'en speed and proton angular gyrofrequency, respectively. Data show that the Cluster spacecraft passed through a series of wavepackets. A strong isolated wavepacket is found to be in accordance with the four Cluster satellites crossing an Alfv\'en vortex, a nonlinear solution to the incompressible MHD equations. A strong agreement is seen between the data from four satellites and a model vortex with a radius of the order of $40$ times the local proton gyro-radii. The polarization at different spacecraft is compared and is found to agree with the vortex model, whereas it cannot be explained solely by the linear plane wave approach., Comment: Submitted

A straightforward method for the reversible modification ofsolid-state properties is a goal being constantly pursued in thedevelopment of molecular switches, and molecular electronicand photonic devices. As one of the most attractive molecule-based switchable materials, spin crossover (SCO) complexespresent different magnetic, optical, electrical and structuralproperties in response to external stimuli (such as temper-ature, pressure, light, or magnetic fields), driven by conver-sionoftheelectronconfigurationbetweenhigh spin(HS)andlow spin (LS) states.

International audience; he turbulence behavior of gas-liquid two-phase flow plays an important role in heat transfer and mass transfer in many chemical processes. In this work, a 2D particle image velocimetry (PIV) was used to investigate the turbulent characteristic of fluid induced by a chain of bubbles rising in Newtonian and non-Newtonian fluids. The instantaneous flow field, turbulent kinetic energy (TKE) and TKE dissipation rate were measured. The results demonstrated that the TKE profiles were almost symmetrical along the column center and showed higher values in the central region of the column. The TKE was enhanced with the increase of gas flow and decrease of liquid viscosity. The maximum TKE dissipation rate appeared on both sides of the bubble chain, and increased with the increase of gas flow rate or liquid viscosity. These results provide an understanding for gas-liquid mass transfer in non-Newtonian fluids.

International audience; This work deals with the effects of the switching frequency of a periodic switching polymerization process (PSPP) with a Ti-based Ziegler-Natta catalyst on the microstructures of ethylene-propylene copolymers in polypropylene/poly(ethylene-co-propylene) (PP/EPR) in-reactor alloys. The compositions and structures of PP/EPR in-reactor alloys are investigated by solvent fractionation, C-13 NMR, gel permeation chromatography (GPC), successive self-nucleation and annealing (SSA) by differential scanning calorimetry (DSC), and statistical deconvolution. The sequence distributions of ethylene-propylene random copolymer (EPR) and ethylene-propylene segmented copolymer (EPS) are successfully deconvoluted from the C-13 NMR spectra of fractionated samples. The results are consistent with the expected effects of the switching frequency on the composition and microstructures of EPR and EPS. A higher switching frequency between the homopolymerization of propylene and the copolymerization of ethylene and propylene increases not only the ratio between the EPS and EPR but also the fractions of long PP segments and long PE segments in the EPS. The effect of the mean residence time on the composition and microstructure of PP/EPR in reactor alloys is also discussed.

International audience; This work aims at shading fundamental insights into mechanisms that dictate the composition and microstructure of polypropylene/poly(ethylene-co-propylene) (PP/EPR) in-reactor alloys produced by the multizone circulating reactor (MZCR) technology, a novel one for polyolefin production. For this purpose, this technology is simulated by a batch process with periodic switching of monomer additions. An increase in the switch frequency leads to a decrease in the fraction of ethylene/propylene random (amorphous) copolymers denoted as EPR and an increase in the fraction and the length of PP segments of ethylene/propylene segmented (partially crystalline) copolymers denoted as EPS. Concomitantly, the size of the dispersed phase domains (EPR) decreases, and its size distribution becomes more uniform as a result of the decrease in the fraction of the EPR and the increase in that of the EPS which acts as a compatibilizer for PP/EPR in-reactor blends. Mechanical properties of the PP/EPR in-reactor blends are also discussed.

International audience; One of the challenges polymer blends may face is their morphological instability. Among the many polymer blends that have been studied in academia and industries, polyamide 6 (PA6) based polymer blends have probably received the most attention. This work shows for the first time that graft copolymers with PA6 as grafts are highly instable under melt polymer blending conditions. Therefore, the structural instability of such graft copolymers can be another crucial factor that dictates the morphology and properties of PA6 based polymer blends as well as their stability, especially those of nano-structured ones.

International audience; The aim of this paper is to investigate the squeezing-to-dripping transition for bubble formation in a microfluidic T-junction by cross-flowing rupture technique using a high-speed digital camera. Experiments were conducted in a glass microfluidic T-junction with the cross-section of the microchannel of 120 mu m wide and 40 mu m deep. N(2) bubbles were generated in glycerol-water mixtures with several concentrations of surfactant sodium dodecyl sulfate (SDS). Three different regimes were identified for generating different kinds of bubbles: squeezing, dripping and transition regimes. Various forces exerted on the gaseous thread in different regimes were analyzed. Long slug bubbles were formed in the squeezing regime, while dispersed bubbles in the dripping regime. The transition regime formed short slug bubbles. The bubble sizes in various regimes could be correlated with several dimensionless numbers such as the ratio of gas/liquid flow rates and capillary number. The two-step model for droplets (Steegmans et al., 2009) was extended to describe the bubble formation.

International audience; The flow distribution behavior of a plate-type constructal flow distributor, which has one inlet and 16 outlets and is designed according to constructal theory to achieve uniform flow distribution with smallest energy dissipation and shortest residence time, is investigated by experiments. When all the outlets are open, the standard flow rate deviation changes from 0.050 to 0.069 and the maximal flow rate ratio, i.e. the ratio of the highest flow rate to the lowest, changes from 1.170 to 1.252 when the averaged Re at the outlet increases from 1020 to 2247. Blocking one or two outlets of one branch will generally decrease the uniformity of the flow distribution, and it will have more influences on the rest outlets of the same branch than on the outlets of other branches.

International audience; The kinetics of the miniemulsion copolymerization of styrene (St) and gamma-methacryloxypropyltrimethoxysilane (MPS) was investigated by studying the effects of the MPS/St weight ratio, the nature and amount of initiator, the suspension pH, and the surfactant concentration on the overall and individual monomer conversions. It was found that the introduction of MPS accelerates the free radical copolymerization reaction due to its higher propagation rate constant and higher water solubility compared to styrene. On the other hand, MPS decreases the copolymerization rate mainly during the second half of the reaction. This is presumed to be due to the formation of alkoxysitane-rich copolymers on the particles surface providing a barrier to radical's entry. The rate of hydrolysis is pH-dependent, and for a given pH, the influence of the surfactant concentration on the hydrolysis rate suggests that the interface between the latex particles and water is the main locus of hydrolysis. Si-29 solid-state NMR analysis showed that the hydrolyzed alkoxysilyl moieties did not condense under neutral conditions even for high MPS/St feed ratios. Premature cross-linking could be also minimized under basic conditions but could not be avoided in acidic media.

International audience; The present study aims at investigating the passage of a gas bubble at a plan liquid-liquid interface both experimentally by using a high-speed video camera and numerically through the volume-of-fluid (VOF) approach. A Newtonian silicone oil was used for the light phase while two different liquids, a Newtonian Emkarox (HV45) solution and a non-Newtonian poly(acryl amide) (PAAm) solution, were employed as the heavy phase. The passage of a gas bubble, generated from a submerged orifice, was followed during its rise in each liquid phase and in particular at the liquid-liquid interface. The original curve of the bubble's position vs time gave interesting insight into the dynamic behavior of the interface. Experimental results show the effect of the bubble size as well as the rheological properties of the heavy phase on the bubble's retention time at the liquid-liquid interface. The preliminary numerical results obtained by the VOF approach are in qualitative agreement with the experimental data.

International audience; Gas phase propylene epoxidation on gold catalysts has attracted wide attention from industry and academia due to its high selectivity. However, it suffers from low propylene conversion and rapid catalyst deactivation. Experiments showed that propylene conversion could be increased by raising H2, O2, or C3H6 concentration in the feed, but the feed compositions were within the explosion limit. It was also shown that the activity of the used catalyst could be fully recovered, but the regeneration temperature was 280 °C, much higher than that for reaction. Therefore a microchannel reactor was devised to suppress explosion and was constructed with Fecralloy, to raise the temperature rapidly for catalyst regeneration by electric heating. In two minutes the temperature of the reactor could be raised from 50 to 300 °C. Catalysts were coated on the alloy belt by dip coating, and the performance of the reactor was evaluated under different operating conditions. Results showed that in the microreactor the overall reaction rate was controlled mainly by the intrinsic reaction rate, and also influenced by film diffusion to a certain extent. The deactivated catalyst was regenerated in the microchannel reactor and the activity was fully recovered.

Electrostatic complexation ; Block copolymers ; Gold nanoparticles ; Polyelectrolytes ; Localized surface plasmon resonance; International audience; In this study, our aim was to control the assembly of plasmonic nanoparticles by using the electrostatic assembly of oppositely charged colloidal species. Gold nanoparticles (Au NPs) were modified with a carboxyl-terminated polymeric ligand, O-(2-carboxyethyl)-O0-(2-mercaptoethyl) heptaethylene glycol (SH-PEG7-COOH), so that they are negatively charged on the pH range 5-10 and they stand elevated ionic strength (up to 1 M NaCl) without loss of colloidal stability. Block copolymers poly[(ethylene glycol) methyl ether-block-(N,N-dimethylamino-2-ethyl methacrylate)] (mPEG-PDMAEMA), with a neutral mPEG block and a pH-sensitive positively charged PDMAEMA block were synthesized by atom transfer radical polymerization (ATRP). The formation of complexes, driven by the electrostatic attraction between opposite charges and by the release of the condensed counter ions, was investigated using dynamic light scattering and spectrophotometry. The relative quantities of polymer chains and nanoparticles in the suspension were shown to affect the size of the formed complexes. In this report, it is also shown that the complex formation is reversible. Stable complexes of typical size 400 nm were formed, which could be used as building blocks for new optical materials.

International audience; The Type VI secretion system (T6SS) is a versatile machine that delivers toxins into either eukaryotic or bacterial cells. At a molecular level, the T6SS is composed of a membrane complex that anchors a long cytoplasmic tubular structure to the cell envelope. This structure is thought to resemble the tail of contractile bacteriophages. It is composed of the Hcp protein that assembles into hexameric rings stacked onto each other to form a tube similar to the phage tail tube. This tube is proposed to be wrapped by a structure called the sheath, composed of two proteins, TssB and TssC. It has been shown using fluorescence microscopy that the TssB and TssC proteins assemble into a tubular structure that cycles between long and short conformations suggesting that, similarly to the bacteriophage sheath, the T6SS sheath undergoes elongation and contraction events. The TssB and TssC proteins have been shown to interact and a specific α-helix of TssB is required for this interaction. Here, we confirm that the TssB and TssC proteins interact in enteroaggregative E. coli. We further show that this interaction requires the N-terminal region of TssC and the conserved α-helix of TssB. Using site-directed mutagenesis coupled to phenotypic analyses, we demonstrate that an hydrophobic motif located in the N-terminal region of this helix is required for interaction with TssC, sheath assembly and T6SS function.

Instances in which natural selection maintains genetic variation in a population over millions of years are thought to be extremely rare. We conducted a genome-wide scan for long-lived balancing selection by looking for combinations of SNPs shared between humans and chimpanzees. In addition to the major histocompatibility complex (MHC), we identified 125 regions in which the same haplotypes are segregating in the two species, all but two of which are non-coding. In six cases, there is evidence for an ancestral polymorphism that persisted to the present in humans and chimpanzees. Regions with shared haplotypes are significantly enriched for membrane glycoproteins, and a similar trend is seen among shared coding polymorphisms. These findings indicate that ancient balancing selection has shaped human variation and point to genes involved in host-pathogen interactions as common targets.

The effect of agitation on the fluidization performance of a gas–solid fluidized bed with a frame impeller is experimentally and numerically investigated. A 3-D unsteady computational fluid dynamics method is used, combining a two-fluid model and the kinetic theory of granular flow. The rotation of the impeller is implemented with a multiple reference frame method. The numerical model is validated using experimental data of the bed pressure drop and pressure fluctuation. Although the minimum fluidizing velocity and bed pressure drop are independent of the impeller agitation, a sufficiently high agitation speed yields higher fluidization performance with reduced bubble diameters and internal circulations of particles. The fluidized bed can be divided into three zones: inlet zone where the gas distribution plays a major role, agitated fluidization zone where the impeller agitation has a positive effect on fluidization, and free fluidization zone where the impeller agitation has no effect on fluidization. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1066–1074, 2013

International audience; Colicins are bacterial toxins that parasitize OM (outer membrane) receptors to bind to the target cells, use an import system to translocate through the cell envelope and then kill sensitive cells. Colicins classified as group A (colicins A, E1–E9, K and N) use the Tol system (TolA, TolB, TolQ and TolR), whereas group B colicins (colicins B, D, Ia, M and 5) use the ExbB–ExbD–TonB system. Genetic evidence has suggested that TolQ and ExbB, as well as TolR and ExbD, are interchangeable, whereas this is not possible with TolA and TonB. Early reports indicated that group B colicin uptake requires energy input, whereas no energy was necessary for the uptake of the pore-forming colicin A. Furthermore, energy is required to dissociate the complex formed with colicin E9 and its cognate immunity protein during the import process. In the present paper, we detail the functional phenotypes and colicin-sensitivity results obtained in tolQ and exbB mutants and cross-complementation data of amino acid substitutions that lie within ExbB or TolQ TMHs (transmembrane helices). We also discuss on a specific phenotype that corresponds to group A colicin-sensitivity associated with a non-functional Tol system.

This study aims to investigate the breakup of slender bubbles in non-Newtonian fluids in microfluidic flow-focusing devices using a high-speed camera and a microparticle image velocimetry (micro-PIV) system. Experiments were conducted in 400- and 600-μm square microchannels. The variation of the minimum width of gaseous thread with the remaining time before pinch-off could be scaled as a power-law relationship with an exponent less than 1/3, obtained for the pinch-off of bubbles in Newtonian fluids. The velocity field and spatial viscosity distribution in the liquid phase around the gaseous thread were determined by micro-PIV to understand the bubble breakup mechanism. A scaling law was proposed to describe the size of bubbles generated in these non-Newtonian fluids at microscale. The results revealed that the rheological properties of the continuous phase affect significantly the bubble breakup in such microdevices. © 2012 American Institute of Chemical Engineers AIChE J,, 2012

International audience; The dissipative particle dynamics (DPD) is used to study the compatibilizing process of an immiscible polymer blend using a graft copolymer as a compatibilizer. Polystyrene (PS) and polyamide 6 (PA6) are chosen as the polymer components of the blend. The graft copolymer is composed of PS as the backbone and PA6 as the grafts. Mesoscale morphology, density distribution, end-to-end distance of PA6 and interfacial tension are investigated. Simulations show that the presence of a graft copolymer contributes to the formation of finer and more uniform dispersed domains by preventing them from collision and coalescence. In the presence of a graft copolymer, the density distribution is more uniform and the dynamic equilibrium of the blend morphology is reached more rapidly. For a given backbone and number of grafts per backbone, the compatibilizing efficiency of the graft copolymer first increases with increasing graft length. However, when the graft length exceeds a certain value, it starts decreasing.

This work aims at developing a steady-state particle size distribution (PSD) model for predicting the size distribution of polypropylene particles in the outflow streams of propylene gas-phase horizontal stirred bed reactors (HSBR), on the one hand and investigating the effect of the catalyst residence time distribution (RTD) on the polymer PSD, on the other hand. The polymer multilayer model (PMLM) is used to describe the growth of a single particle. Knowing the PSD and RTD of a Ziegler–Natta type of catalyst and polymerization kinetics, this model allows calculating the polymer PSD of propylene polymerization in the HSBRs. The calculated polypropylene PSDs agree well with those obtained from the industrial reactors. The results reveal that both the PSD and the RTD of the catalyst affect the polymer PSD but in different manners. The effect of RTD on the PSD is less significant in the case of a nonuniform size catalyst feed. This model also allows investigating the effects of other process parameters on the polymer PSD under steady-state conditions, including intraparticle mass- and heat-transfer limitations, initial catalyst size, and polymer crystallinity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

This article reports on a route to synthesizing fluorescent labeled graft copolymers, on the one hand; and on a concept of tracer-compatibilizer for facile build-up of emulsification curves of polymer blends, on the other hand. For these purposes, blends composed of polystyrene (PS) and polyamide 6 (PA6) are chosen. The synthesis of the corresponding tracer-compatibilizer consists of three steps: (1) copolymerization of styrene with 3-isopropenyl-α,α'-dimethybenzyl isocyanate (TMI); (2) conversion of a fraction of the isocyanate moieties of the resulting copolymer into anthracene ones upon reacting with 9-(methylamino-methyl)anthracene (MAMA); and (3) polymerization of e-caprolactam (CL) from the remaining isocyanate moieties. The resulting fluorescent labeled graft copolymer, denoted as PS-g-PA6-Ant, is used to build up emulsification curves of PS/PA6 blends in a twin screw extruder (TSE), showing great usefulness of the concept of tracer-compatibilizer. POLYM. ENG. SCI. 2012. © 2011 Society of Plastics Engineers

International audience; The viscosity distribution of the liquid around a rising bubble in carboxymethyl cellulose (CMC) aqueous solutions was measured experimentally by particle image velocimetry (PIV). The effect of the concentration of CMC solutions on the viscosity distribution around a bubble and the coupling relations between the viscosity field, flow field and shear stress field were also studied. Results indicated that the specific viscosity (non-dimensionalized by eta(0)) decreases with the increase in CMC solution concentration due to a shear thinning effect. Within the experimental range, similar viscosity distributions of liquids around a rising bubble were found: a hollow cylindrical low viscosity region around the bubble wake and a high viscosity region in the central bubble wake.

Contains fulltext : 96888.pdf (Publisher’s version ) (Open Access) EMPIRE10 (Evaluation of Methods for Pulmonary Image REgistration 2010) is a public platform for fair and meaningful comparison of registration algorithms which are applied to a database of intrapatient thoracic CT image pairs. Evaluation of nonrigid registration techniques is a nontrivial task. This is compounded by the fact that researchers typically test only on their own data, which varies widely. For this reason, reliable assessment and comparison of different registration algorithms has been virtually impossible in the past. In this work we present the results of the launch phase of EMPIRE10, which comprised the comprehensive evaluation and comparison of 20 individual algorithms from leading academic and industrial research groups. All algorithms are applied to the same set of 30 thoracic CT pairs. Algorithm settings and parameters are chosen by researchers expert in the configuration of their own method and the evaluation is independent, using the same criteria for all participants. All results are published on the EMPIRE10 website (http://empire10.isi.uu.nl). The challenge remains ongoing and open to new participants. Full results from 24 algorithms have been published at the time of writing. This paper details the organization of the challenge, the data and evaluation methods and the outcome of the initial launch with 20 algorithms. The gain in knowledge and future work are discussed.

International audience; The aim of this work is to investigate experimentally the bubble breakup in a microfluidic T-junction divergence using a high-speed digital camera and a micro-Particle Image Velocimetry (micro-PIV) system. The breakup and non-breakup of N-2 bubbles in glycerol-water mixtures with several concentrations of sodium dodecyl sulphate (SDS) as surfactant were studied with capillary number ranging from 0.001 to 0.1. The cross section of PMMA square microchannel is 400 mu m wide and 400 mu m deep. Four various flow patterns were observed at the T-junction by changing gas and liquid flow rates. The dynamics of three various types of symmetric breakup of bubbles were investigated. The symmetric breakup of bubbles type I is mainly controlled by the augmented pressure in liquid phase. The symmetric breakup of bubbles type II is controlled by both the increased pressure and viscous forces. In the symmetric breakup of bubbles type III, a scaling law for the minimum bubble neck and the remaining time during bubble breaking process were found. The transitions between breakup and non-breakup of bubbles were investigated, and a power-law relationship between bubble extension and capillary number was proposed to predict the transitions between adjacent regimes. Our experimental results reveal that the bubble breakup in a microfluidic T-junction divergence is similar to the droplet behaviours in such a device (Jullien et al., 2009; Leshansky and Pismen, 2009; Link et al., 2004).

International audience; A new thermodynamic model based on an equation of state for square-well chain fluid with variable range (SWCF-VR) is proposed to describe the thermodynamic properties of aqueous solutions of ionic liquids. In this approach the electrostatic interactions are characterized via the mean spherical approximation and the ionic associations between the cations and anions of the ionic liquid are considered through the shield-sticky approach. The liquid densities, osmotic coefficients, and vapor pressures of aqueous solutions of nine ionic liquids (ILs) containing [Cxmim][Br] (x = 2, 6), [C 4mim][BF4] and [Cxmim][MSO4] (x=1, 3, 4) have been modeled with the new model. Two ionic parameters for each anion and three for each cation of the ionic liquids were adjusted to experimental liquid densities and osmotic coefficients, and the corresponding average deviations are only 0.87% and 2.49%, respectively. Using the same ionic parameters, the vapor pressures of ionic liquid solutions are accurately predicted. The predicted equilibrium constants of the ionic association between the cations and anions of ILs in water were consistent with experimental observations. © 2011 American Chemical Society.

International audience; The study investigated the hepatitis B virus (HBV) genotypic resistance profile in 1803 nucleos(t)ide analogue (NA)-experienced Chinese patients with chronic HBV infection. Serum HBV DNA was extracted, and the reverse transcriptase region was analysed by a high-sensitive direct PCR sequencing and verified by clonal sequencing if necessary. Drug-resistant mutations were detected in 560 of the 1803 patients, including 214 of 490 patients who received lamivudine (LAM), 35 of 428 patients who received adefovir (ADV), five of 18 patients who received telbivudine and 306 of 794 patients who received various sequential/combined NA therapies. ADV-resistant mutations were detected in 36 of 381 patients who received LAM and then switched-to ADV in contrast to one of 82 patients who received ADV add-on LAM. Entecavir (ETV)-resistant mutations were detected not only in LAM- and ETV-treated patients but also in LAM-treated ETV-naïve patients. Double mutations rtM204I and rtL180M were detected more frequently in genotype C than in genotype B virus, and patients infected with this mutant had higher alanine transaminase levels than those infected with mutant containing the rtM204I substitution alone. Multidrug-resistant HBV strains were identified in eight patients, including two novel strains with mutational patterns rtL180M + A181V + S202G + M204V + N236T and rtL180M + S202G + M204V + N236T. The results provide new information on HBV genotypic resistance profiles in a large cohort of Chinese patients with chronic HBV infection and may have important clinical implication for HBV drug resistance management in China.

International audience; The nonlinear dynamics of in-line bubbles rising with coalescence in non-Newtonian Carboxymethylcellulose sodium (CMC) fluids was studied through the techniques such as the multiresolution signal decomposition and the chaotic time series analysis. The temporary signals of bubble passages collected by an optical sensing device at different heights were investigated by a 12-level wavelet decomposition and the scalewise characteristics of bubble motion were extracted and analyzed. The chaotic time series analysis distinguished the periodicity or the deterministic chaos of bubble motion successsfully. The calculation of Kolmogorov entropy proves that in the ranges of experimental heights and gas flowrates, the bubble rising dynamics becomes more chaotic with the increase of height, and reaches the maximum chaotic extent in a certain height, while with the further increase of height, the chaotic extent decreases slowly. With the increase of gas flowrate, at the lower height, the bubble rising dynamics changes from periodicity to deterministic chaos, and at the higher heights it reaches the maximum chaotic extent in a certain gas flowrate; however, for both cases, it has little change in the higher gas flowrates. Moreover, with the increase of CMC concentration, the bubble rising dynamics becomes less chaotic when the height is beyond a certain value.

International audience; This communication describes the gas―liquid two-phase flow patterns and the formation of bubbles in non-Newtonian fluids in microfluidic flow-focusing devices. Experiments were conducted in two different polymethyl methacrylate (PMMA) square microchannels of, respectively, 600 x 600 and 400 x 400 μm. N2 bubbles were generated in non-Newtonian polyacrylamide (PAAm) solutions of different concentrations. Slug bubble, missile bubble, annular and intermittent flow patterns were observed at the cross-junction by varying gas and liquid flow rates. Gas and liquid flow rates, concentration of PAAm solutions, and channel size were varied to investigate their effect on the mechanism of bubble formation. The bubble size was proportional to the ratio of gas/ liquid flow rate for slug bubbles and could be scaled with the ratio of gas/liquid flow rate as a power―law relationship for missile bubbles under wide experimental conditions.

The aim of this work is to investigate the bubble formation in non-Newtonian fluids in a microfluidic T-junction by crossflowing rupture technique, using a high-speed digital camera. Experiments were conducted in a glass microchannel with 120 μm wide and 40 μm deep. N 2 bubbles were generated in different concentrations of polyacrylamide (PAAm) solutions. Various flow patterns were observed at the T-junction by varying gas and liquid flow rates. The breakup mechanism for bubbles was investigated to gain insight into the effects of flow rates and concentrations of PAAm solutions on bubble size. The gaseous thread collapses at a constant speed in the collapse stage; while during the final pinch-off stage, the variation of the minimum width W m of the gaseous thread with the remaining time ( T − t ) could be scaled as W m ∼ ( T − t ) 0.21 . The bubble size increases non-linearly with the gas/liquid flow rates ratio, and decreases with the concentration of PAAm solutions.

International audience; A rheometer-reactor was designed to study the effect of the presence of multiwalled-carbon nanotubes (MWCNT) on the kinetics of the activated anionic polymerization of ε-caprolactam (AAPCL). The presence of the MWCNT slowed down the kinetics of the AAPCL. Moreover, the higher the MWCNT content, the more important its adverse effect on the kinetics of the AAPCL. On the other hand, the presence of the MWCNT could also adversely affect the molar mass of the resulting polyamide 6 when its content was high enough (about 1.0 wt % or higher). Possible mechanisms are discussed.

International audience; The solubility of materials is a thermodynamic variable that depends on their chemical composition and with temperature. Solubility is also affected by the pH, by the presence of additional species in the solution, and by the use of different solvents. On electrolyte, the calculation of solubility requires that the mean ionic activity coefficient be known along with a thermodynamic solubility product.

The present study aims at scaling the formation of slug bubbles in flow-focusing microfluidic devices using a high-speed digital camera and a micro particle image velocimetry (μ-PIV) system. Experiments were conducted in two different polymethyl methacrylate square microchannels of respectively 600 × 600 and 400 × 400 μm. N2 bubbles were generated in glycerol–water mixtures with several concentrations of surfactant sodium dodecyl sulfate. The influence of gas and liquid flow rates, the viscosity of the liquid phase and the width of the microchannel on the bubble size were explored. The bubble size was correlated as a function of the width of the microchannel W c, the ratio of the gas/liquid flow rates Q g/Q l and the liquid Reynolds number. During the pinch-off stage, the variation of the minimum width of the gaseous thread W m with the remaining time could be scaled as $$ W_{\text{m}} \propto ({\frac{{Q_{\text{g}} }}{{Q_{\text{l}} }}})^{ - 0.15} (T - t)^{1/3} . $$ The velocity fields in the liquid phase around the thread, determined by μ-PIV measurements, were obtained around a forming bubble to reveal the role of the liquid phase.

International audience; The velocity, shape, and trajectory of the rising bubble in polyacrylamide (PAM) and carboxymethylcellulose (CMC) aqueous solutions were experimentally investigated using a set of homemade velocimeters and a video camera. The effects of gas the flowrate and solution concentration on the bubble terminal velocity were examined respectively. Results show that the terminal velocity of the bubble increases with the increase in the gas flowrate and the decrease in the solution concentration. The shape of the bubble is gradually flattened horizontally to an ellipsoid with the increase in the Reynolds number (Re), Eoumltvoumls number (Eo), and Morton number (Mo). With the increase in the Re and Eo, the rising bubble in PAM aqueous solutions begin to oscillate, but there is no oscillation phenomena for CMC aqueous solutions. By dimensional analysis, the drag coefficient of a single bubble in non-Newtonian fluids in a moderate Reynolds number was correlated as a function of Re, Eo, and Archimedes number (Ar) based on the equivalent bubble diameter. The predicted results by the present correlation agree well with the experimental data.

International audience; he influence of malic acid, which acts as an impurity on the cooling crystallization of zinc lactate is investigated in this paper by monitoring the relative supersaturation and the number of crystals during crystallization. The presence of malic acid increases the solution solubility and makes the metastable zone wider; it also changes the habit of the crystal. The purity of the final products is shown to be influenced by the amount and size of seed crystals, cooling rate, seeding temperature and final temperature, but appears to depend mainly on the particle size and level of supersaturation. Residual supersaturation thresholds are observed that depend on the final temperature. A model is proposed to predict the steady-state supersaturation value from the final temperature at a given impurity concentration. This model is based on Kubota and Gibbs equations.

In this paper, Zr based bulk metallic glass (BMG) composite consisting of nanocrystals embedded in the amorphous matrix was synthesized by controlled annealing treatment of a Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 amorphous alloy. The homogeneous plastic deformation behavior of the BMG composite was characterized in the supercooled liquid region, exhibiting non-Newtonian steady state plastic flow over the investigated strain rate domain. Based upon the analysis of rheological data in terms of a modified mechanistic model, it is revealed that the mechanism of the non-Newtonian plastic flow varies with temperature, which is closely related to the presence of nanocrystals within the glassy matrix.

International audience; This work is concerned with the dependence of the compatibilizing efficiency of graft copolymers on the composition of immiscible polymer blends. A series of graft copolymers of polystyrene (PS) and polyamide 6 (PA6), denoted as PS-g-PA6, with different molecular structures were used as compatibilizers. The PS-g-PA6 was more efficient for the PS/PA6 (80/20) blend than for the PS/PA6 (20/80) one, indicating that a graft copolymer whose backbone and grafts match the matrix and the disperse phase polymers, respectively, has higher compatibilizing efficiency. This is in disagreement with the literature. Moreover, whatever the blend composition, for PS-g-PA6 graft copolymers with the same backbone and the same number of grafts per backbone, the longer the grafts, the higher their compatibilizing and stabilizing efficiency; for a given backbone/graft mass ratio, the longer the grafts and concomitantly the smaller the number of grafts per backbone, the higher the compatibilizing and stabilizing efficiency of the graft copolymer.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 1162-1166, The integrated project (IP) Crystal Clear has been finalized in June 2009 and thus a chapter of more than 5 years successful collaboration between European solar cell research institutes and industry is closed. This paper reviews the achievements within the 4th subproject (SP4) of Crystal Clear dealing with the development of advanced solar cell concepts. Within SP4, 12 of the 16 partners have participated and have formed a productive consortium. The goal of this subproject was the further reduction of the cell production costs to enable the psychological important Si PV module price below 1 Euro/Watt. This should be reached by novel cell designs and manufacturing processes in order to achieve a process cost reduction of 40% (cost per Wp). One major effort was put in the development of novel cell concepts and processes suited for thin wafers in industrial fabrication. Three cell concepts were distinguished and developed by the participating institutes: i-PERC, MWT with full Al, and solar cells with laser fired contacts (PERC-LFC). In addition to the effort to implement these concepts into an industrial type of process with large area wafers, excellent results have been achieved on EFG and RGS ribbons. World record results with laboratory-type processes could be reported, with efficiencies of 18.2 % on EFG ribbons and 14.4 % on RGS ribbons. The defect mechanism of these materials has been studied in detail and efficiency limits have been indicated. The paper will refer to the separate contributions submitted to the conference by the different partners on specific topics.