Polyethylene nanocomposites based on intercalation of N-alkyl amines within KTiNbO5 structure

This article describes the synthesis of nanostructured organic/inorganic hybrid materials based on the modification of the titanoniobate oxide KTiNbO₅ by N-alkyl amines via an acido-basic reaction. X-ray diffraction and scanning electron microscopy have showed the successful intercalation of the organic molecules between the inorganic layers. The hybrid nanofillers previously obtained have been incorporated in a polyethylene matrix by melt intercalation. The morphology and thermomechanical properties of the nanocomposites have been investigated. It has been revealed that the modification of the oxide improves the dispersion and the exfoliation in the matrix leading to an increase of Young's modulus and of the degradation temperature. The TEM observations coupled with EDS mapping is revealed to be one interesting mean of characterization for this study.     

Acetogenic coccoid spore-forming bacteria isolated from the rumen

Thirteen strains of a new acetogenic bacterium were isolated from the rumen contents of lambs, llamas and bisons. This paper is the first report of Gram-positive coccoid spore-forming bacteria occurring in chains and able to use H2 + CO2 as energy source and produce acetate from this gas mixture. One of them, chosen as the reference strain for its efficiency in utilizing H2/CO2 likely via the acetyl-CoA pathway, was characterized in detail. The G + C ratio of the DNA of the organism was 46.5 mol%. The temperature and pH optimum were 37 degrees-40 degrees C and 6.3-6.8, respectively. Numerous organic substrates including some o-methylate aromatic compounds were used heterotrophically. The full 16S rRNA gene sequence was determined. The phylogeny, physiology, morphology and numerous features described here are sufficiently different from those of any bacteria described today to justify the definition of a new species. The name "New acetogenic bacterium" is temporarily proposed, awaiting a future taxonomic revision of the genus Clostridium.     

NMR study of the phosphonomethylation reaction on chitosan

N-Phosphonomethylation of chitosan reaction was studied and optimized using different reaction conditions. NMR spectroscopy was an important tool in this work to study this reaction and the α-aminomethylphosphonic acid function introduced onto chitosan was unequivocally characterized by ³¹P and ¹³C NMR analyses. But surprisingly, whatever the reaction conditions used, N-phosphonomethylation reaction of chitosan cannot be dissociated from a side reaction: the N-methylation reaction of chitosan. A mechanism was proposed to explain the formation of this side product.     

Stability of Protective Oxide Layer Against Corrosion: Solubility Measurements of Chromium in Soda Lime Silicate Melts

The solubility of chromium oxide (Cr₂O₃) in soda lime silicate glasses was studied as a function of temperature (1,200 °C ≤ T ≤ 1,350 °C), oxygen fugacity (?12 ≤ log fO₂ ≤ ?0.6) and glass composition (Na₂O–CaO–xSiO₂; x = 3, 4, 5 and 6). The fO₂ was proved to induce several oxidation states of Cr for a given glass composition at a fixed temperature. The influence of glass composition on the Cr solubility was interpreted in terms of the optical basicity Λ concept. An increase in the melt basicity led to an increase in the Cr solubility for the experiments conducted under oxidizing conditions. The total dissolved Cr also showed a significant increase with increasing temperature for a given fO₂ and glass composition. The results proved that the stability of Cr₂O₃ scale against corrosion was profoundly influenced by fO₂, T and melt basicity.     

The Impact of Iron Oxide Concentration on the Performance of Molten Oxide Electrolytes for the Production of Liquid Iron Metal

Metallurgical and Materials Transactions B - The effect of iron oxide concentration on the conductive behavior of a molten oxide electrolyte has been investigated at 1823 K using stepped...     

3D Printing of Flexible Composites via Magnetophoresis: Toward Medical Application Based on Low-Frequency Induction Heating Effect

In this work, a commercial extrusion 3D printer is used to process magnetic pastes into desired 3D structures. The magnetic pastes prepared in the authors' laboratory are mixtures of Fe₃O₄ (iron oxide), microparticles, and PDMS (polydimethylsiloxane) polymer. After multiple composition tests, they produced pastes compatible with the 3D printer that can be additively manufactured into flexible ferromagnetic samples. The design optimization, together with the characterizations of composites, are investigated. Magnetic particles do not simply mix with the polymer but formed a chain-like structure under the influence of a magnetic field during the printing process. The chain-like structure induces magnetic and thermal anisotropies. The relative permeability and the low-frequency induction heating (LFIH) effect are improved. The authors' development is highly relevant in healthcare applications, especially endovascular ablation for varicose treatment.     

Experimental and numerical investigation of the gas‐phase effectiveness of phosphorus compounds

The effectiveness of phosphorus‐containing compounds as gas‐phase combustion inhibitors varies widely with flame type. To understand this behavior, experiments are performed with dimethyl methylphosphonate (DMMP) added to the oxidizer stream of methane–air co‐flow diffusion flames (cup‐burner configuration). At low volume fraction, phosphorus (via DMMP addition) is shown to be about four times as effective as bromine (via Br₂ addition) at reducing the amount of CO₂ required for extinguishment; however, above about 3000 μL/L to 6000 μL/L, the marginal effectiveness of DMMP is approximately zero. In contrast, the diminished effectiveness does not occur for Br₂ addition. To explore the role of condensation of active phosphorus‐containing compounds to the particles, laser‐scattering measurements are performed. Finally, to examine the behavior of the flame stabilization region (which is responsible for extinguishment), premixed burning velocity simulations with detailed kinetics are performed for DMMP addition to methane–air flames. Analyses of the numerical results are performed to understand the variation in the inhibition mechanism with temperature, agent loading, and stoichiometry, to interpret the loss of effectiveness for DMMP in the present experiments. Copyright © 2015 John Wiley & Sons, Ltd.     

Measurement of the 4He Chemical Potential in Phase-Separated 3He-4He Liquid Mixtures

As a first step towards thermodynamic measurements in highly polarised dense ³ He fluids, an accurate determination of the ⁴ He chemical potential ₄ was performed in unpolarised phase-separated ³ He- ⁴ He liquid mixtures at low pressures (0-1 bar) over a temperature range 0.12 - 0.65 K. A method introduced by H. London and relying on heat flush effects was used. Two volumes containing : a) a cold, phase-separated helium mixture and b) a warmed, pure ⁴ He liquid are connected by a narrow tube, and their temperatures are recorded under various conditions. The results agree with existing data obtained by the same technique for T >0.2K, but cannot be analysed with the simple regular solution model fitting vapour pressure data at T >0.6K. The sensitivity of the technique is shown to be sufficient to observe expected effects of nuclear polarisation on ₄.