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Toulouse, France

Calcium phosphate apatites are inorganic compounds encountered in many different mineralized tissues. Bone mineral, for example, is constituted of nanocrystalline nonstoichiometric apatite, and the production of "analogs" through a variety of methods is frequently reported. In another context, the ability of solid surfaces to favor the nucleation and growth of "bone-like" apatite upon immersion in supersaturated fluids such as SFB is commonly used as one evaluation index of the " bioactivity" of such surfaces. Yet, the compounds or deposits obtained are not always thoroughly characterized, and their apatitic nature is sometimes not firmly assessed by appropriate physicochemical analyses. Of particular importance are the "actual" conditions in which the precipitation takes place. The precipitation of a white solid does not automatically indicate the formation of a "bone-like carbonate apatite layer" as is sometimes too hastily concluded: "all that glitters is not gold." The identification of an apatite phase should be carefully demonstrated by appropriate characterization, preferably using complementary techniques. This review considers the fundamentals of calcium phosphate apatite characterization discussing several techniques: electron microscopy/EDX, XRD, FTIR/Raman spectroscopies, chemical analyses, and solid state NMR. It also underlines frequent problems that should be kept in mind when making "bone-like apatites." © 2013 Christophe Drouet. Source

Masse J.-P.,ArcelorMittal | Poquillon D.,ENSIACET
Scripta Materialia | Year: 2013

Entangled materials can be manufactured using fibers made from various materials, such as carbon, glass or steel. The mechanical properties of these low-density materials are linked to their architecture (fiber orientation, number of contacts, etc.). Specimens can be produced with and without cross-links between fibers by sintering for steel wool or by using epoxy spraying for carbon or glass fibers. Experimental mechanical compression tests were performed on these materials. The results were analyzed taking into account the architecture thanks to the relationships existing between morphological data and macroscopic mechanical behavior. © 2012 Published by Elsevier Ltd. Source

Pignolet O.,ENSIACET | Jubeau S.,University of Nantes | Vaca-Garcia C.,ENSIACET | Michaud P.,CNRS Pascal Institute
Journal of Industrial Microbiology and Biotechnology | Year: 2013

The past decade has seen a surge in the interest in microalgae culture for biodiesel production and other applications as renewable biofuels as an alternative to petroleum transport fuels. The development of new technologies for the culture of these photosynthetic microorganisms and improved knowledge of their biochemical composition has spurred innovation in the field of high-value biomolecules. These developments are only economically viable if all the microalgae fractions are valorized in a biorefinery strategy. Achieving this objective requires an understanding of microalgae content and the cellular localization of the main biomolecular families in order to develop efficient harvest and sequential recovery technologies. This review summarizes the state of the art in microalgae compositions and topologies using some examples of the main industrially farmed microalgae. © 2013 Society for Industrial Microbiology and Biotechnology. Source

Nehme N.,ENSIACET | Mathieu F.,CNRS Chemical Engineering Laboratory | Taillandier P.,ENSIACET
Food Microbiology | Year: 2010

The present study was aimed to evaluate the impact of the co-culture on the output of malolactic fermentation and to further investigate the reasons of the antagonism exerted by yeasts towards bacteria during sequential cultures. The Saccharomyces cerevisiae D strain/Oenococcus oeni X strain combination was tested by applying both sequential culture and co-culture strategies. This pair was chosen amongst others because the malolactic fermentation was particularly difficult to realize during the sequential culture. During this traditional procedure, malolactic fermentation started when alcoholic fermentation was achieved. For the co-culture, both fermentations were conducted together by inoculating yeasts and bacteria into a membrane bioreactor at the same time. Results obtained during the sequential culture and compared to a bacterial control medium, showed that the inhibition exerted by S. cerevisiae D strain in term of decrease of the malic acid consumption rate was mainly due to ethanol (75%) and to a peptidic fraction (25%) having an MW between 5 and 10 kDa. 0.4 g l-1 of l-malic acid was consumed in this case while 3.7 g l-1 was consumed when the co-culture was applied. In addition, there was no risk of increased volatile acidity during the co-culture. Therefore, the co-culture strategy was considered effective for malolactic fermentation with the yeast/bacteria pair studied. © 2009 Elsevier Ltd. All rights reserved. Source

Marcelin S.,ENSIACET | Pebere N.,ENSIACET | Regnier S.,Catholic Institute of Toulouse
Electrochimica Acta | Year: 2013

This paper focuses on the characterisation of the electrochemical behaviour of a martensitic stainless steel in 0.1 M NaCl + 0.04 M Na2SO 4 solution and is a part of a study devoted to crevice corrosion resistance of stainless steels. Polarisation curves and electrochemical impedance measurements were obtained for different experimental conditions in bulk electrolyte. X-ray photoelectron spectroscopy (XPS) was used to analyse the passive films. At the corrosion potential, the stainless steel was in the passive state and the corrosion process was controlled by the properties of the passive film formed during air exposure. During immersion in the deaerated solution, the passive film was only slightly modified, whereas it was altered both in composition and thickness during immersion in the aerated solution. After cathodic polarisation of the stainless steel electrode surface, the oxide film was almost totally removed and the surface appeared to be uniformly active for oxygen reduction. The new passive film, formed at the corrosion potential, was enriched with iron species and less protective. Impedance diagrams allowed the characterisation of both the oxide film (high-frequency range) and the charge transfer process (low-frequency range). © 2012 Elsevier Ltd. Source

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