Trace element geochemistry of ordinary chondrite chondrules: the type I/type II chondrule dichotomy

We report trace element concentrations of silicate phases in chondrules from LL3 ordinary chondrites Bishunpur and Semarkona. Results are similar to previously reported data for carbonaceous chondrites, with rare earth element (REE) concentrations increasing in the sequence olivine < pyroxene < mesostasis, and heavy REE (HREE) being enriched by 1-2 orders of magnitude (CI-normalized) relative to light REE (LREE) in ferromagnesian silicates, although no single olivine with very large LREE/HREE fractionation has been found. On average, olivine in type II chondrules is poorer in refractory lithophile incompatible elements (such as REE) than its type I counterpart by a factor of ~2. This suggests that olivine in type I and II chondrules formed by batch and fractional crystallization, respectively, implying that type II chondrules formed under faster cooling rates (> ~ 10 K/h) than type I chondrules. Appreciable Na concentrations (3-221 ppm) are measured in olivine from both chondrule types; type II chondrules seem to have behaved as closed systems, which may require chondrule formation in the vicinity of protoplanets or planetesimals. At any rate, higher solid concentrations in type II chondrule forming regions may explain the higher oxygen fugacities they record compared to type I chondrules. Type I and type II chondrules formed in different environments and the correlation between high solid concentrations and/or oxygen fugacities with rapid cooling rates is a key constraint that chondrule formation models must account for.Comment: 46 pages, 7 figure

Appropriation et identification des territoires du vin : la lutte entre grands et petits propriétaires du « Corton »

A partir d’une analyse de cas, les conflits autour de la délimitation de l’appellation du vin Corton en Bourgogne dans l’entre-deux-guerres, le texte distingue deux modes de construction du territoire : l’identification, processus de désignation par l’Etat et l’appropriation, processus de revendication par les intéressés eux-mêmes. Face à l’impossible identification légitime des territoires viticoles par l’Etat, la loi de 1919 sur les appellations d’origine impose le recours à la voie judiciaire pour régler les différends. Les acteurs en conflit s’affrontent alors sur des appropriations et définitions divergentes du territoire. Chacun revendique des registres de justification différents pour tenter d’imposer son territoire. Le territoire n’est nullement un héritage naturel, mais le fruit d’un affrontement social. Si les grands propriétaires jouent d’arguments économiques et historiques pour fonder leur revendication à une zone d’appellation restrictive, les petits propriétaires, nouveaux entrants de l’appellation et de l’économie viticole de luxe, avancent eux des arguments politiques, républicains, pour séduire les tribunaux de la IIIe République. La définition du territoire et les règles du marché dépendent d’un jeu qui dépasse largement la lutte strictement économique variant selon les contextes politiques et les rapports de forces sociaux.“appellation d’origine”, wine, territory, process of identification, membership, Burgundy

The formation conditions of enstatite chondrites: Insights from trace element geochemistry of olivine-bearing chondrules in Sahara 97096 (EH3)

We report in situ LA-ICP-MS trace element analyses of silicate phases in olivine-bearing chondrules in the Sahara 97096 (EH3) enstatite chondrite. Most olivine and enstatite present rare earth element (REE) patterns comparable to their counterparts in type I chondrules in ordinary chondrites. They thus likely share a similar igneous origin, likely under similar redox conditions. The mesostasis however frequently shows negative Eu and/or Yb (and more rarely Sm) anomalies, evidently out of equilibrium with olivine and enstatite. We suggest that this reflects crystallization of oldhamite during a sulfidation event, already inferred by others, during which the mesostasis was molten, where the complementary positive Eu and Yb anomalies exhibited by oldhamite would have possibly arisen due to a divalent state of these elements. Much of this igneous oldhamite would have been expelled from the chondrules, presumably by inertial acceleration or surface tension effects, and would have contributed to the high abundance of opaque nodules found outside them in EH chondrites. In two chondrules, olivine and enstatite exhibit negatively sloped REE patterns, which may be an extreme manifestation of a general phenomenon (possibly linked to near-liquidus partitioning) underlying the overabundance of light REE observed in most chondrule silicates relative to equilibrium predictions. The silicate phases in one of these two chondrules show complementary Eu, Yb and Sm anomalies providing direct evidence for the postulated occurrence of the divalent state for these elements at some stage in the formation reservoir of enstatite chondrites. Our work supports the idea that the peculiarities of enstatite chondrites may not require a condensation sequence at high C/O ratios as has long been believed.Comment: 30 pages, 7 figure

Iron-catalyzed hydrosilylation of CO2: CO2 conversion to formamides and methylamines

International audienceno abstrac

Les syndicats viti-vinicoles en Bourgogne de 1884 à la mise en place des AOC

Méthode d’approche du sujet Retracer l’historique de ce travail de thèse me semble tout d’abord nécessaire et ce, afin d’exposer d’une part, l’évolution de ma méthode de travail et d’autre part, la construction étape par étape du sujet. Ce travail a débuté avec un mémoire de DEA portant déjà sur le syndicalisme viti-vinicole en Bourgogne, sur la période allant de la loi Waldeck Rousseau du 21 mars 1884 à la Seconde Guerre mondiale . Cette étude mettait en exergue l’action des professionnels d..

Les syndicats viti-vinicoles en Bourgogne de 1884 à la mise en place des AOC

Méthode d’approche du sujet Retracer l’historique de ce travail de thèse me semble tout d’abord nécessaire et ce, afin d’exposer d’une part, l’évolution de ma méthode de travail et d’autre part, la construction étape par étape du sujet. Ce travail a débuté avec un mémoire de DEA portant déjà sur le syndicalisme viti-vinicole en Bourgogne, sur la période allant de la loi Waldeck Rousseau du 21 mars 1884 à la Seconde Guerre mondiale . Cette étude mettait en exergue l’action des professionnels d..

Catalytic hydrosilylation of oxalic acid: chemoselective formation of functionalizedC2-products

International audienceOxalic acid is an attractive entry to functionalized C2-products because it can be formed by C–C coupling of two CO2 molecules under electrocatalytic reduction. Herein, we describe the first attempts to reduce oxalic acid by catalytic hydrosilylation. Using B(C6F5)3 as a Lewis acidic catalyst, oxalic acid can be converted to reduced C2-molecules, with high chemoselectivity, under mild reaction conditions

Phytalgic®, a food supplement, vs placebo in patients with osteoarthritis of the knee or hip: a randomised double-blind placebo-controlled clinical trial

International audienceINTRODUCTION: The medicinal treatment of osteoarthritis (OA) is mostly symptomatic to relieve pain and incapacity with analgesics and non-steroidal anti-inflammatory drugs (NSAIDs), drugs with well-known risks. Complementary medicines might reduce the symptoms of OA and decrease the need for NSAIDs. This study tested the effects of a food supplement, Phytalgic, on pain and function in patients with osteoarthritis and their use of analgesic and NSAIDs. METHODS: A randomized double-blind parallel-groups clinical trial compared Phytalgic (fish-oil, vitamin E, Urtica dioica) to a placebo for three months, in 81 patients with OA of the knee or hip using NSAIDs and/or analgesics regularly. The main outcome measures were use of NSAIDs (in Defined Daily Doses per day - DDD/day) or analgesics (in 500 mg paracetamol-equivalent tablets per week (PET/week) measured each month, and Western Ontario-McMaster University Osteo-Arthritis Index (WOMAC) function scales. RESULTS: After three months of treatment, the mean use of analgesics in the active arm (6.5 PET/week) vs. the placebo arm (16.5) was significantly different (P < 0.001) with a group mean difference of -10.0 (95% CI: -4.9 to -15.1). That of NSAIDs in the active arm (0.4 DDD/day) vs the placebo arm (1.0 DDD/day) was significantly different (P = 0.02) with a group mean difference of - 0.7 DDD/day (95% CI: -0.2 to -1.2). Mean WOMAC scores for pain, stiffness and function in the active arm (respectively 86.5, 41.4 and 301.6) vs the placebo arm (resp. 235.3, 96.3 and 746.5) were significantly different (P < 0.001) with group mean differences respectively of -148.8 (95% CI: -97.7 to -199.9), -54.9 (95% CI: -27.9 to -81.9) and -444.8 (95% CI: -269.1 to -620.4). CONCLUSIONS: The food supplement tested appeared to decrease the need for analgesics and NSAIDs and improve the symptoms of osteoarthritis. TRIAL REGISTRATION: Clinicaltrials.gov NCT00666523