Brillante L.,French National Center for Scientific Research |
Bois B.,French National Center for Scientific Research |
Bois B.,Institut Universitaire de France |
Mathieu O.,French National Center for Scientific Research |
And 4 more authors.
Journal of Hydrology | Year: 2014
Modern irrigation techniques require accurate, rapid, cost-effective, spatial measurement of soil moisture. Electrical Resistivity Tomography (ERT) meets most of these requirements, but needs to be calibrated for each use because it is very sensitive to differences in soil characteristics. In this study, a pedotransfer function approach is used to remove the need for site-specific calibration, allowing ERT to be used directly to measure soil moisture. The study site was a hillslope vineyard, where eight calcaric-cambisol soil profiles were identified. From 2012 to 2013, 23000 soil volume wetness measurements were acquired by Time Domain Reflectometry, and over 100000 electrical resistivity data were collected in 160 ERT acquisitions. To better understand the ERT signal, soil texture, gravel content, cation exchange capacity, CaCO3, pH, organic carbon and total nitrogen were analysed in 64 soil samples from the study site. The sensitivity of ERT to differences in soil characteristics makes it difficult to establish a unique model linking electrical resistivity and soil moisture in heterogeneous soils. This study presents two possible solutions to overcome this problem, which are differentiated by the availability of data on soil characteristics. When these data are not available, it is possible to fit a number of different models for each homogeneous soil layer, but a site-specific calibration is necessary at least once. Conversely, when soil characteristics are available, they can be integrated into the model to build a pedotransfer function. A unique, accurate model is obtained in this way for all samples. In soils with similar characteristics to those observed, the function can be used directly to measure soil moisture by ERT. Developing pedotransfer functions such the one presented here could greatly improve, simplify and develop the use of electrical resistivity to measure soil moisture. © 2014 Elsevier B.V.
Malika C.,University of Science and Technology Houari Boumediene |
Kenza A.,University of Science and Technology Houari Boumediene |
Yasmine A.O.,University of Science and Technology Houari Boumediene |
Abdeltif A.,National Graduate School of Chemistry, Rennes |
And 2 more authors.
Desalination and Water Treatment | Year: 2010
Ion exchange technology is currently the best way to remove nitrate from drinking water. A commercial resin was tested to examine the effectiveness of adsorption for nitrate removal; the resin is Amberlite IRA 400, since it is considered the most promising owing to its chemical stability and ability to control surface chemistry. KNO3 solution (22.15 mg L-1) was used in batch adsorption experiments. Adsorbent dosages were varied from 0.875 to 5 g L-1. An increase in adsorbent dosage increased the percent removal of nitrate. The retention was initially very fast and maximum retention was observed within 30 min of agitation. Two simplified kinetic models were considered to investigate the ion exchange mechanisms, i.e. the liquid film diffusion and the intraparticle diffusion models, and it was shown that the former controlled the beginning of the process while the latter predominated at the end of the process. © 2010 Desalination Publications. All rights reserved.
Small-angle and wide-angle X-ray scattering study of slow relaxation following phase transitions of new bolaamphiphiles based on N-(12-Betainylamino- dodecane)-octyl β-D-Glucofuranosiduronamide Chloride
Jeftic J.,National Graduate School of Chemistry, Rennes |
Jeftic J.,University Europe Enne Of Bretagne |
Berchel M.,University of Western Brittany |
Berchel M.,University Europe Enne Of Bretagne |
And 4 more authors.
Spectroscopy Letters | Year: 2012
In the present study, we investigated the polymorphism and its time-dependence of a new series of bolaamphiphile molecules based on N-(12-Betainylamino-dodecane)-octyl β-D-Glucofuranosiduronamide Chloride. To obtain six members of this series, the length of the main bridging chain and the lateral chain were varied in order to modify the hydrophilic-lipophilic balance. Another chemical modification was to introduce a diacetylenic unit in the middle of the bridging chain to study the influence of the π-π stacking on the supramolecular organization of these molecules. Dry bolaamphiphiles self-organize in supramolecular structures such as lamellar crystalline structure, L c; lamellar gel structure, L β; lamellar fluid structure, L α′; and lamellar isotropic structure, L. Thermal hysteresis of these structures, following phase transitions, are investigated by small-angle and wide-angle X-ray scattering. Once the thermal cycle is accomplished, the system remains in the kinetically stabilized undercooled high-temperature phase at the temperature of 20°C. Subsequently, the time-dependence of the relaxation to the thermodynamically stable phase is followed, and very slow relaxation for a period on the order of hours or days is observed. The study of the polymorphism and the stability of various phases of this new series of bolaamphiphileswhich are issued from natural primary resources (sugar beet and wheat) and thus interesting for potential application in pharmaceutical, cosmetics, or food industrywas undertaken in this work. © 2012 Taylor & Francis Group, LLC.
Huc D.,IRSTEA |
Huc D.,University Europe Enne Of Bretagne |
Huc D.,Agro ParisTech |
Huc D.,French National Institute for Agricultural Research |
And 9 more authors.
International Dairy Journal | Year: 2014
An important characteristic of semi-hard cheeses with propionic acid fermentation is the eyes. However, growth mechanisms of the eyes are only qualitatively understood. In this study, X-ray computed tomography was used to monitor eye growth inside cheeses during ripening without disrupting any mechanism. Chemical and rheological analyses carried out in two different zones of the cheeses revealed a spatial-dependency, with the position the eyes significantly correlated to their final volume, and a different CO2 production by CO2-producing propionic acid bacteria with 27.7 mmol kg-1 in the centre and 18.7 mmol kg-1 in the outer zone. Furthermore, the present study allowed quantification using image processing: the overall cheese porosity grew from 0.03% at the beginning of ripening up to 4.60% at the end. Moreover, the porosity was 10 times lower, and the volume of eyes 13 times lower, in the outer zone than in the centre of the cheese. © 2014 Elsevier Ltd.
Bourmaud A.,University Europe Enne Of Bretagne |
Corre Y.-M.,University Europe Enne Of Bretagne |
Baley C.,University Europe Enne Of Bretagne
Industrial Crops and Products | Year: 2014
To take advantage of the mechanical performance of plant fibers and avoid their degradation, it is necessary to develop biocomposites by working on the least aggressive process conditions possible. The use of thermoplastic polymers with low processing temperatures is one possible way. In this study, tests were performed on poly-(butylene-succinate) (PBS) flax composite, extruded and injected at 140. °C. They have a good level of tensile or impact properties compared to poly-(propylene) (PP) or l-poly-(lactide) (PLLA) based biocomposites. Nanoindentation measurements were performed in situ on the composites. Despite the low Young's modulus of PBS, it was shown that the use of a moderate process temperature limits the downward stiffness of the flax cell walls. Finally, it was demonstrated that the PBS could be associated with PLLA for making flax fiber reinforced biocomposites. The introduction of PBS, with adjustable volume fractions, improves elongation at break and impacts on the behavior of PLLA-flax composites, whilst retaining high performance mechanical properties. Thus, it is possible to elaborate fully biodegradable composites with the desired mechanical properties. © 2014 Elsevier B.V.