Kitsou Dubois and the Weightless Body

Annick Bureaud, the author of this article, is a key figure in technology, science, and the arts in Europe, through her writing and her organizational work for Leonardo/Olats. Her publications include Connexions: Art, Réseaux, Media in 2002 with Nathalie Magnan (Ensba Press), which brought major texts on art and communication technologies to French speaking audiences, and her articles as a freelance art critic for Art Press, a major French contemporary art magazine. Here she brings to the English-speaking world the work of Kitsou Dubois, a major figure in the European dance world who has been working with issues relating to outer space, weightlessness, and scientific research in dance. Dubois recently began to use sensor technologies.     

Characterization of cylindrospermopsin chlorination

In temperate countries, the occurrence of cyanobacterial blooms threatens drinking water resources. Consequently, cyanotoxins are increasingly considered in water treatment, and their reactions with chlorine used to disinfect drinking water are particularly investigated. This study presents new elements for further understanding of cylindrospermopsin chlorination, through reactants and by-products monitoring, UV spectrum examination, and cytotoxicity assessment on human intestinal Caco-2 cells. On the one hand, the evolution of mixture UV spectrum indicated that cylindrospermopsin was quickly transformed at least into one intermediate by-product. While mass spectrometry experiments confirmed that cylindrospermopsin was almost totally transformed within 5 min, chlorine was consumed up to 20 min after the beginning of the reaction with a rate of 5 mol per mol of toxin. Then, LC-MS analysis gave rise to the formation of a third cylindrospermopsin by-product in addition to 5-chloro-cylindrospermopsin and cylindrospermopsic acid previously identified. Thanks to the accurate mass measurement provided by the LTQ-Orbitrap mass spectrometer, this new and stable chlorination by-product was assigned the chemical formula C₁₃H₁₈N₄O₇S. On the other hand, both of the mitochondrial and lysosomal activities measured on Caco-2 cells revealed that cylindrospermopsin chlorination significantly decreases mixture cytotoxicity.     

Odd random phase multisine EIS for organic coating analysis

In this paper the different steps involved in an integrated methodology to measure, analyze and model electrochemical systems in a correct and reliable way are shown for Al-rich metallic coated steel with an additional organic coating. This methodology is based on the use of an odd random phase multisine excitation signal and was proposed by our group previously. The use of this multisine excitation signal decreases the measurement time. Moreover, it allows to perform a rigourous data-analysis and to quantify the signal-to-noise ratio, the level of non-linear and non-stationary behaviour. It was shown that by using this technique the optimal measurement conditions can be chosen based on a trade-off between signal-to-noise ratio and non-linear behaviour. Moreover, in the modeling procedure the noise, non-linearities or non-stationarities can be taken into account. The methodology allows a statistical evaluation of the proposed model for the coated metal, indicating whether model errors are still present or not.     

Application of Synchrotron Radiation Techniques for Model Validation of Advanced Structural Materials

Synchrotron radiation techniques represent powerful tools to characterize materials down to the nanometer level. This paper presents a survey of the state‐of‐the‐art synchrotron‐based techniques which are particularly well‐suited for investigating materials properties. Complementary X‐ray absorption techniques such as extended X‐ray absorption fine structure (EXAFS), X‐ray magnetic circular dichroism (XMCD), photoemission electron microscopy (PEEM) are used to address the individual local atomic structure and magnetic moments in Fe–Cr model systems. The formation of atomic clusters/precipitates in such systems is also investigated by means of scanning transmission X‐ray microscopy (STXM). Such advanced analytical techniques can not only offer valuable structural and magnetic information on such systems, they can also serve for validating computational calculations performed at different time and length scales which can help improve materials lifetime predictions.     

Study of Fullerenes, Nanotubes and Nanowires by Transmission Electron Microscopy

The arc discharge reactor developped by Kratschmer et al^l produces a variety of new carbonaceous solids, including fullerenes and different kinds of graphitic cages of nanometric size, which can be hollow or filled with various materials. Complementary to neutron and X ray diffraction techniques, transmission electron microscopy rapidly appeared among the most important techniques for studying the structures of fullerenes and fullerites^2-6. Very generally, it allows us to obtain diffraction patterns of micronic size crystallites and the different imaging modes provide an unique tool to investigate in real space the morphology of the crystallites, structural defects faults at microscopic and nanometric scales^6-8. It is possible to perform very local chemical analysis and to study chemical environments in order to determine the nature of chemical bonds⁹. Futhermore, it is possible to study phase transitions through in situ experiments^5,10-12 and the behaviour of fullerites upon electron irradiation¹³. The interest of this technique has appeared even more crucial with the discovery of narotubes¹⁴ and their ability to be filled¹⁵ since, because of their nanometric size, the electron microscopy is at the moment the unique tool allowing their study and is therefore a challenge in the development of these new materials for applications in nanotechnology.     

Early-age autogenous cracking of cementitious matrices: physico-chemical analysis and micro/macro investigations

High-performance cement-based materials, characterized by low water-to-cement (W/C) ratio and high cement content, are sensitive to early-age cracking because their autogenous shrinkage rate and magnitude are particularly high during this period. This article firstly presents experimental tools especially designed for the measurement of free and restrained autogenous shrinkage at early-age. Then, the results of a multi-parameter experimental study conducted on three different types of binder are analyzed. The physico-chemical deformations of cement pastes and mortars were measured from the very early-age up to several days in saturated and autogenous conditions to investigate the effects of binder, water-to-binder ratio, presence of aggregates and temperature on the driving-mechanisms leading to early-age autogenous cracking. Complementary tests such as hydration rate measurement and microscopic observations were also performed. Among the three binders used, the blast furnace slag cement shows higher chemical strain, for a given quantity of chemically-bound water, and higher early-age autogenous shrinkage. The presence of aggregates generates a local restraining effect of cement paste deformations, leading to the formation of microcracks in the surrounding cement paste. Ring test results reveal that the first through crack of cement pastes systematically appears for maximal internal stress values lower than the material tensile strength, estimated with three-point flexural tests. This phenomenon may be due to diffuse damage of the cementitious matrix, whose deformations are partially restrained.     

Young modulus, mechanical and electrical properties of isolated individual and bundled single-walled boron nitride nanotubes

The Young modulus of individual single-walled boron nitride nanotubes (SW-BNNTs) was determined using a high-resolution transmission-electron microscope (HRTEM)-atomic force microscope (AFM) set-up. The Young modulus and maximum stress for these NTs were deduced from the analysis of the stress-strain curves, and discussed as a function of the considered value for the shell thickness of an SW-BNNT. The elastic properties of bundles of SW-BNNTs were also investigated. All these experiments revealed that SW-BNNTs are very flexible. Furthermore, the electrical behavior of these SW-BNNTs was also analyzed employing a scanning tunneling microscope (STM) holder integrated with the same HRTEM. I/V curves were measured on individual tubes as well as on bundles of SW-BNNTs.     

Prebiotic effects and intestinal fermentation of cereal arabinoxylans and arabinoxylan oligosaccharides in rats depend strongly on their structural properties and joint presence

Scope: Cereal arabinoxylan (AX) is one of the main dietary fibers in a balanced human diet. To gain insight into the importance of structural features of AX for their prebiotic potential and intestinal fermentation properties, a rat trial was performed. Methods and results: A water unextractable AX‐rich preparation (WU‐AX, 40% purity), water extractable AX (WE‐AX, 81% purity), AX oligosaccharides (AXOS, 79% purity) and combinations thereof were included in a standardized diet at a 5% AX level. WU‐AX was only partially fermented in the ceco‐colon and increased the level of butyrate and of butyrate producing Roseburia/E. rectale spp. Extensive fermentation of WE‐AX and/or AXOS reduced the pH, suppressed relevant markers of the proteolytic breakdown and induced a selective bifidogenic response. Compared with WE‐AX, AXOS showed a slightly less pronounced effect in the colon as its fermentation was virtually complete in the cecum. Combining WU‐AX and AXOS caused a striking synergistic increase in cecal butyrate levels. WU‐AX, WE‐AX and AXOS together combined a selective bifidogenic effect in the colon with elevated butyrate levels, a reduced pH and suppressed proteolytic metabolites. Conclusion: The prebiotic potential and fermentation characteristics of cereal AX depend strongly on their structural properties and joint presence.