Lixiviation of argillaceous rocks: Impact of oxidation degree states on organic compound mobilization

This work aims to study the influence of oxidation degree state which reached by organic matter included in argillaceous rocks on lixiviation and mobilization of compounds. Experimental lixiviation was carried out on two argillaceous rocks sampled in the surface deposit of the Andra laboratory (Bure, France). Molecular and spectroscopic characterizations of the organic matter extracts reveal two different oxidation levels reached by these samples: (i) a well preserved and (ii) an oxidized samples. Dissolved organic matter content and molecular investigation of sediment bitumen show that hydrophobic molecules (hydrocarbons) remain stable during lixiviation whereas specific polar compounds (alkanoic acids) are progressively removed by water. Moreover, occurrence of secondary alkanols with a molecular distribution similar to initial n-alkanes suggests that even in the well preserved sample, oxidation already occurs and that secondary alkanols can be used as specific markers for low intensity oxidation.     

Revisiting micro hot-embossing with moulds in non-conventional materials

Manufacturing moulds in non-metallic tooling materials using non-conventional structuring techniques is explored for rapid and/or alternative tooling for hot-embossing of polymers. Some challenges and advantages of producing embossing tools by deep reactive ion etching in silicon and/or replica-casting in poly(dimethylsiloxane) and utilizing them in the replication process are highlighted.     

Bismuth-induced effects on optical,lattice vibrational,and structural properties of bulk GaAsBi alloys

Bulk GaAs_{1 - x}Bi_x/GaAs alloys with various bismuth compositions are studied using power- and temperature-dependent photoluminescence (PL), Raman scattering, and atomic force microscopy (AFM). PL measurements exhibit that the bandgap of the alloy decreases with increasing bismuth composition. Moreover, PL peak energy and PL characteristic are found to be excitation intensity dependent. The PL signal is detectable below 150 K at low excitation intensities, but quenches at higher temperatures. As excitation intensity is increased, PL can be observable at room temperature and PL peak energy blueshifts. The quenching temperature of the PL signal tends to shift to higher temperatures with increasing bismuth composition, giving rise to an increase in Bi-related localization energy of disorders. The composition dependence of the PL is also found to be power dependent, changing from about 63 to 87 meV/Bi% as excitation intensity is increased. In addition, S-shaped temperature dependence at low excitation intensities is observed, a well-known signature of localized levels above valence band. Applying Varshni’s law to the temperature dependence of the PL peak energy, the concentration dependence of Debye temperature (β) and thermal expansion coefficient (α) are determined. AFM observations show that bismuth islands are randomly distributed on the surface and the diameter of the islands tends to increase with increasing bismuth composition. Raman scattering spectra show that incorporation of Bi into GaAs causes a new feature at around 185 cm^-1 with slightly increasing Raman intensity as the Bi concentration increases. A broad feature located between 210 and 250 cm^-1 is also observed and its intensity increases with increasing Bi content. Furthermore, the forbidden transverse optical (TO) mode becomes more pronounced for the samples with higher bismuth composition, which can be attributed to the effect of Bi-induced disorders on crystal symmetry.

PACS

78.55Cr 78.55-m 78.20-e 78.30-j     

Training Concept for Environmental Emergency Measures: Structuring Knowledge

During an environmental emergency, intervenors must make rapid decisions to the best of their knowledge regarding the environment and the event itself. To insure optimal decision-making, intervenors must acquire the necessary reflexes through numerous and realistic training sessions. It is, therefore, necessary to provide economical training methods. Advances in computer science in the area of data-bases and expert systems allow one to envisage the development of computer tools to further emergency response training. This article is an overview of the work carried out in this area. The authors have developed a computer method for training in environmental emergency response in the context of an oil spill in the St. Laurence River. Knowledge structuring and management methods are presented, following an overview of the study context. Lastly, ongoing computer developments are summarized in order to validate the methodology that has been developed. The work carried out opens the door to applications for other types of emergency response and serves to illustrate the usefulness of such a computerized approach.     

Applications of LIGA technology to precision manufacturing of high-aspect-ratio micro-components and -systems: a review

The by far leading technology for manufacturing MEMS devices is Si-micromachining with its various derivatives. However, many applications of microsystems have requirements on materials basis, geometry, aspect ratio, dimensions, shape, accuracy of microstructures, and number of parts that cannot be fulfilled easily by mainstream silicon-based micromachining technologies. LIGA, an alternative microfabrication process combining deep X-ray lithography, plating-through-mask and molding, enables the highly precise manufacture of high-aspect-ratio microstructures with large structural height ranging from hundreds to thousands of micrometers thick. These tall microstructures can be produced in a variety of materials with well-defined geometry and dimensions, very straight and smooth sidewalls, and tight tolerances. LIGA technology is also well suited for mass fabrication of parts, particularly in polymer.Many microsystems benefit from unique characteristics and advantages of the LIGA process in terms of product performance. The LIGA technology is briefly reviewed. The strengths of the manufacturing method and its main fields of application are emphasized with examples taken from various groups worldwide, especially in micromechanics and microoptics.     

The DNA sequence analysis of the HAP4–LAP4 region on chromosome XI of Saccharomyces cerevisiae suggests the presence of a second aspartate aminotransferase gene in yeast

The nucleotide sequence of a 19 000 base pair region from the left arm of chromosome XI of Saccharomyces cerevisiae has been determined and analysed. It covers the HAP4–GFA1–LAP4 loci already described. As expected HAP4, GFA1 and LAP4 genes have been found and six new open reading frames (ORFs) with a coding capacity of more than 100 amino acid residues have been identified. One of them (YKL461) shows a high degree of identity with an aspartate aminotransferase gene. This raises the question of a second aspartate aminotransferase gene in yeast. A second ORF (YKL462) shows features compatible with a membranous localization. The other ORFs do not show a similarity with any known gene. A member of the highly repetitive ‘CAT’ DNA sequence is present.     

Rutting of bituminous mixtures: wheel tracking tests campaign analysis

Rutting is one of the main failure modes in pavement structures subjected to mechanical loading. Wheel Tracking Testers (WTT) devices used to evaluate the rutting performance of bituminous mixtures were investigated by Working Group 3 (WG3) “Mechanical Tests for Bituminous Materials”, of the RILEM ATB Technical Committee 206. Three different bituminous layer systems (A, B and C) currently used in road construction were compared to evaluate the abilities of “small” and “large” WTT devices to quantify road materials rutting performance. The tested specimens were cut from large slabs extracted from the onsite pavement structures. Seven laboratories located in seven different countries, were involved in the testing program. Results show that the mean rate of rutting for “small” WTT devices is faster than for “large” WTT devices. Systems A and C show equivalent performance and can be considered good in terms of the European Standard’s requirement. Results from system B indicate poor performance and it does not comply with the specifications of the standard. Nevertheless, a visual evaluation of the rutting showed a very good performance on the road for systems A and B and no apparent difference could be noted between these two systems.