Alkoxy- and hydroxycyclization of enynes catalyzed by Pd(II) and Pt(II) catalysts

The development of a novel reaction ideal in terms of atom economy was achieved. The scope of the reaction was evaluated in the presence of Pd and Pt catalysts. The first enantioselective Pt-promoted enyne carboalkoxycyclization was developed in up to 85 % stereoselectivity. This ideal atom-economical reaction afforded the corresponding functionalized five-membered carbo- and heterocycles in good to excellent yields. The use of silver salts combined with (R)-Ph-BINEPINE, a monophosphane atropisomeric ligand, was found to be the best-suited combination for moderate to high enantioselectivities on carbonated and nitrogenated substrates

Characterizing the Mechanics of Fracturing from Earthquake Source Parameter and Multiplet Analyses: Application to the Soultz-sous-Forêts Hot Dry Rock site

In 2000 and 2003, two massive hydraulic fracturing experiments were carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forêts, France. The objective was to create a dense network of enhanced permeability fractures, which would form the heat exchanger. The injection of water in the fractured rock generated a high level of microseismic activity: around 30,000 and 90,000 micro-earthquakes were triggered during the injection of 2000 and 2003 respectively. From this around 14,000 and 9,000 events were then located to characterize the extent of the stimulated zones and hence of the fracture network. Then, the source parameters of each event, like seismic moments and stress drops, were computed automatically to characterize the mechanics of the fracturing. We found for example that the total seismic moment released is proportional to the injected fluid volume. This suggests that the injection flow rate could be a means to control the earthquake strength released during the stimulation and perhaps also control the effectiveness of the stimulation. Finally, we performed a multiplet analysis of a subset of these data to identify microearthquakes having similar waveforms. Multiplets are considered to be microearthquakes that occur on the same fracture plane and therefore may represent either seismically activated structures and/or permeable fractures induced by hydraulic fracturing. We identified 350 multiplets among 1000 analyzed events. We relocated them precisely by cross-spectrum analysis and found that they belong to sub-horizontal structures, likely permeable fractures stimulated by the injection.Massachusetts Institute of Technology. Earth Resources Laborator

Simulation of cellular irradiation with the CENBG microbeam line using GEANT4

Light-ion microbeams provide a unique opportunity to irradiate biological samples at the cellular level and to investigate radiobiological effects at low doses of high LET ionising radiation. Since 1998 a single-ion irradiation facility has been developed on the focused horizontal microbeam line of the CENBG 3.5 MV Van de Graaff accelerator. This setup delivers in air single protons and alpha particles of a few MeV onto cultured cells, with a spatial resolution of a few microns, allowing subcellular targeting. In this paper, we present results from the use of the GEANT4 toolkit to simulate cellular irradiation with the CENBG microbeam line, from the entrance to the microprobe up to the cellular medium.Comment: 6 pages, 8 figures, presented at the 2003 IEEE-NSS conference, Portland, OR, USA, October 20-24, 200

Fracture Mapping in the Soultz-sous-Forets Geothermal Field from Microearthquake Relocation

In 2003, a massive hydraulic fracturing experiment was carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forêts, France. The two week injection of water generated a high level of microseismic activity. About 90,000 microearthquakes were triggered during and after this fluid injection. Of these, 21,000 events, detected at all stations, were located individually with a grid search algorithm to characterize the extent of the seismic zones and, ultimately, of the fracture network. The accuracy of these initial locations was around 70 meters, not sufficient to map detailed fracture patterns. We undertook a relocation effort using two different techniques: Joint Hypocenter Determination (JHD) and Multiplet analysis. The JHD technique allows for the simultaneous location of a group of events and the determination of a common set of station corrections. We added the “collapsing” method to the JHD results to further consolidate the hypocenters. This was followed by a multiplet analysis for identifying microearthquakes with similar waveforms. We found 7463 events whose seismograms correlated with a correlation coefficient of 0.8 or higher, most of which were doublets. For the relative location of the correlated events, we computed the delay in travel-time by wavelet analysis. We found that multiplets were located on small planes with lengths of a hundred to several hundred meters striking mostly along N150°E. Comparing the distribution of seismicity with fluid outflows during the fluid injection, we observed that majority of events were concentrated along the newly created fractures.Massachusetts Institute of Technology. Earth Resources Laborator

To set up pedagogical experiments in a virtual lab: methodology and first results

This paper concerns a methodology for setting up web based experiments by distinguishing two perspectives: the learning perspective (which tasks will be scheduled for pupils and tutors, how they are planned and what learning objectives they may attempt), and separately, the experiment perspective (how teachers or researchers may use trails of this experiment, the first to improve their teaching, the last to various research objectives). The both are described by computable “scenarios” expressed with an educational modeling language, Learning Design Language (LDL). Scenarios are then implemented on a platform (LearningLab platform) to be played by pupils and tutors and further analyzed by exploiting trails of each run

Une infrastructure logicielle pour instrumenter l'expérimentation des EIAH

International audienceCet article a pour objet de présenter une plate-forme logicielle développée dans le but de faciliter le travail des chercheurs dans la mise en place et la réalisation d'expérimentations dans le domaine des EIAH. Ce travail a été réalisé dans le cadre de l'action « Shared Virtual Lab » (SVL) du réseau d'excellence Kaleidoscope, et les outils ont été exploités pour la réalisation d'une expérimentation complexe mettant en oeuvre simultanément plusieurs EIAH développés au sein de l'équipe MeTAH du LIG. Le scénario décrivant l'activité des élèves et des enseignants impliqués dans l'expérimentation est décrit en langage LDL et interprété par la plate-forme. Les traces d'activité produites par les logiciels expérimentés et par la plate-forme sont centralisées dans une base de données XML. Elles ont été exploitées en temps réel par un outil de suivi destiné aux enseignants

Variabilità spazio-temporale della microalga <i>Chrysophaeum taylorii</i> Lewis &amp; Bryan lungo le coste nord-orientali della Sardegna = Spatio-temporal variabilty of the microalga <i>Chrysophaeum taylorii</i> Lewis &amp; Bryan along North-Eastern Sardinian coasts

In the summer months of 2010 the cell density of the alien benthic microalga Chrysophaeum taylorii Lewis &amp; Bryan (Pelagophyceae) was assessed on hard benthic substrates in sixteen study sites along the north-eastern coast of Sardinia in order to obtain useful information on spatial and temporal variations of the species in the area during summer

Esperimento di rimozione degli ammassi mucillaginosi della microalga alloctona <i>Chrysophaeum taylorii</i> Lewis &amp; Bryan = Experiment of removal of the mucilaginous aggregates by the alien microalga <i>Chrysophaeum taylorii</i> Lewis &amp; Bryan

A manipulative experiment was carried out in a small bay of Tavolara Punta Coda Cavallo Marine Protected Area in order to investigate the triggers for formation and storage of the macroscopic mucilaginous aggregates of the benthic microalga Chrisophaeum taylorii Lewis &amp; Bryan (Pelagophyceae) and to test the efficacy of mucillage removal