Binding of ²³⁹Pu and ⁹⁰Sr to organic colloids in soil solutions: evidence from a field experiment

Colloidal transport has been shown to enhance the migration of plutonium in groundwater downstream from contaminated sites, but little is known about the adsorption of ??Sr and plutonium onto colloids in the soil solution of natural soils. We sampled soil solutions using suction cups, and separated colloids using ultrafiltration to determine the distribution of 23?Pu and ??Sr between the truly dissolved fraction and the colloidal fraction of the solutions of three Alpine soils contaminated only by global fallout from the nuclear weapon tests. Plutonium was essentially found in the colloidal fraction (>80%) and probably associated with organic matter. A significant amount of colloidal ??Sr was detected in organic-rich soil solutions. Our results suggest that binding to organic colloids in the soil solutions plays a key role with respect to the mobility of plutonium in natural alpine soils and, to a lesser extent, to the mobility of ??Sr.     

Coumarins from Seseli devenyense Simonk.: Isolation by Liquid–Liquid Chromatography and Potential Anxiolytic Activity Using an In Vivo Zebrafish Larvae Model

Different types of anxiety disorders have become the number one mental health issue in developed countries. The search for new, safer and effective drug-like molecules among naturally derived substances faces two difficulties: an efficient method of isolation compounds with a high-purity and high-throughput animal model for activity assay. Thus, the aim of the present study was to isolate by liquid–liquid chromatography high-purity rare coumarins from the fruits of Seseli devenyense Simonk. and evaluate their anxiolytic effect (defined as reversed thimotaxis) using a 5-days post-fertilization (dpf) Danio rerio larvae model. Liquid–liquid chromatography enabled the isolation of one simple hydroxycoumarin (devenyol) and four pyranocoumarins (cis-khellactone, d-laserpitin, isolaserpitin and octanoyllomatin). The anxiolytic effect was defined as a decrease in the time spent in the boundaries of the living space (also described as reversed thigmotaxis). Our results show that all isolated courmarins exerted a significant influence on the anxiety behavior (anxiolytic activity) in the zebrafish larvae model. According to our knowledge, this is the first report of anxiolytic activity of pyranocoumarins and devenyol.     

Design of High Speed AWGN Communication Channel Emulator

This paper presents a method for designing a high accuracy white gaussian noise generator suitable for communication channel emulation. The proposed solution is based on the combined use of the Box-Muller method and the central limit theorem. The resulting architecture provides a high accuracy AWGN with a low complexity architecture for a digital implementation in FPGA. The performance is studied by means of MATLAB simulations and various complexity figures are given.     

Dielectric,ferroelectric, and energy storage properties in dysprosium doped sodium bismuth titanate ceramics

In this work, Na_0.5(Bi_1-xDy_x)_0.5TiO₃ (0?≤?x?≤?15%) ceramics were prepared via solid state reaction method and were characterized. A stable and pure perovskite phase was revealed by X-ray diffraction analysis for all compositions and a symmetry change from rhombohedral to orthorhombic phase was detected beyond 10% of Dy substitution. The incorporation of Dy³⁺ into Sodium Bismuth Titanate (Na_0.5Bi_0.5TiO₃) matrix allows a substantial decrease of the coercive field, an increase in the resistivity, and leads to a high stability of the dielectric permittivity (??/?_(150?°C) ≤?±?15%) over a wide temperature range. Furthermore, this system was found to exhibit improved energy storage properties at high temperatures with a maximum energy density of 1.2?J/cm³ obtained for 2%Dy composition at 200?°C. The obtained results are very promising for energy storage capacitors operating at high temperatures.     

The impact of a sewage treatment plant's effluent on sediment quality in a small bay in Lake Geneva (Switzerland–France). Part 2: Temporal evolution of heavy metals

The Bay of Vidy is the most contaminated area of Lake Geneva, Switzerland, as a result of the release of treated and untreated waste water from the municipal sewage treatment plant of the city of Lausanne and its surroundings. The reconstruction of the historical deposition of heavy metals in the sediment of the bay has been performed by the analysis of several dated (radiocaesium) sediment cores. The presence of sewage‐derived contaminants in the Bay of Vidy since the beginning of the sewage treatment plant's operations in 1964 is clearly observed, when a sharp increase in heavy metal contents is recorded, with maximum concentrations of cadmium, copper, zinc and lead occurring between the late 1960s and early 1970s. Despite considerable improvement in recent times, the present concentrations of the investigated heavy metals in sediments of the Bay of Vidy are still higher than concentrations measured at the centre of the lake, the latter close to Lake Geneva's natural background values. It is concluded that the quantity of heavy metals deposited in the bay is considerable and, because of sediment instability, will constitute a potential hazard for biota.     

Assessment of elastic parameters of human skin using dynamic elastography

Sonoelastography and transient elastography are two ultrasound-based techniques that facilitate noninvasive characterization of the viscoelastic properties of soft tissues by investigating their response to shear mechanical excitation. Young's modulus is the principle assessment parameter. Because it defines local tissue stiffness, it is of major interest for the medical imaging and cosmetic industries as it could replace subjective palpation by yielding local, quantitative information. In this paper, we describe a new high-resolution device capable of measuring local Young's modulus in very thin layers (1-5 mm) and devoted to the in vivo evaluation of the elastic properties of human skin. It uses an ultrasonic probe (50 MHz) for tracking the displacements induced by a 300 Hz shear wave generated by a ring surrounding the transducer. The displacements are measured using a conventional cross-correlation technique between successive ultrasonic back-scattered echoes. First, this noninvasive technique has been experimentally proven to be accurate for investigating elasticity in different skin-mimicking phantoms. Second, data were acquired in vivo on human forearms. As expected, Young's modulus was found to be higher in the dermis than in the hypodermis and other soft tissues.     

Additive Composition of Supervised Self-Organizing Maps

The learning of complex relationships can be decomposed into several neural networks. The modular organization is determined by prior knowledge of the problem that permits to split the processing into tasks of small dimensionality. The sub-tasks can be implemented with neural networks, although the learning examples cannot be used anymore to supervise directly each of the networks. This article addresses the problem of learning in a modular context, developing in particular additive compositions. A simple rule allows defining efficient training, and combining, for example, several Supervised-SOM networks. This technique is important because it introduces interesting generalizations in many modular compositions, permitting data fusion or sequential combinations of neural networks. This revised version was published online in August 2006 with corrections to the Cover Date.