Compound-Specific δ^(34)S Analysis of Volatile Organics by Coupled GC/Multicollector-ICPMS

We have developed a highly sensitive and robust method for the analysis of δ^(34)S in individual organic compounds by coupled gas chromatography (GC) and multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The system requires minimal alteration of commercial hardware and is amenable to virtually all sample introduction methods. Isobaric interference from O_2^+ is minimized by employing dry plasma conditions and is cleanly resolved at all masses using medium resolution on the Thermo Neptune MC-ICPMS. Correction for mass bias is accomplished using standard−sample bracketing with peaks of SF6 reference gas. The precision of measured δ^(34)S values approaches 0.1‰ for analytes containing >40 pmol S and is better than 0.5‰ for those containing as little as 6 pmol S. This is within a factor of 2 of theoretical shot-noise limits. External accuracy is better than 0.3‰. Integrating only the center of chromatographic peaks, rather than the entire peak, offers significant gain in precision and chromatographic resolution with minimal effect on accuracy but requires further study for verification as a routine method. Coelution of organic compounds that do not contain S can cause degraded analytical precision. Analyses of crude oil samples show wide variability in δ^(34)S and demonstrate the robustness and precision of the method in complex environmental samples

Smooth critical points of planar harmonic mappings

In a work in 1992, Lyzzaik studies local properties of light harmonic mappings. More precisely, he classifies their critical points and accordingly studies their topological and geometrical behaviours. We will focus our study on smooth critical points of light harmonic maps. We will establish several relationships between miscellaneous local invariants, and show how to connect them to Lyzzaik's models. With a crucial use of Milnor fibration theory, we get a fundamental and yet quite unexpected relation between three of the numerical invariants, namely the complex multiplicity, the local order of the map and the Puiseux pair of the critical value curve. We also derive similar results for a real and complex analytic planar germ at a regular point of its Jacobian level-0 curve. Inspired by Whitney's work on cusps and folds, we develop an iterative algorithm computing the invariants. Examples are presented in order to compare the harmonic situation to the real analytic one.Comment: 36 pages, 5 figure

Prise en compte des interactions multi-domaines lors de l’évaluation de la fiabilité prévisionnelle des systèmes mécatroniques

The mechatronic systems are hybrid, dynamic, interactive and reconfigurable. Therefore their dysfunctional modeling is very difficult. Multi-physical interactions between components have impacts on the degradation or on system failures, leading thus to more uncertainty in reliability evaluation. The work presented in this paper aims to improve the integration of multi-domain interactions in the reliability assessment of mechatronic systems. After a presentation of the state of the art of mechatronic systems reliability estimation methods, we propose to represent multi domain interactions by influential factors in the dysfunctional model. We generally use proportional hazard models; in the case of an interaction represented by a temperature stress, Arrhenius model is used

Sulfur isotopic compositions of individual organosulfur compounds and their genetic links in the Lower Paleozoic petroleum pools of the Tarim Basin, NW China

During thermochemical sulfate reduction (TSR), H2S generated by reactions between hydrocarbons and aqueous sulfate back-reacts with remaining oil-phase compounds forming new organosulfur compounds (OSCs) that have similar δ34S values to the original sulfate. Using Compound Specific Sulfur Isotope Analysis (CSSIA) of alkylthiaadamantanes (TAs), alkyldibenzothiophenes (DBTs), alkylbenzothiophenes (BTs) and alkylthiolanes (TLs), we have here attempted to differentiate OSCs due to primary generation and those due to TSR in oils from the Tarim Basin, China. These oils were generated from Cambrian source rocks and accumulated in Cambrian and Ordovician reservoirs. Based on compound specific sulfur isotope and carbon isotope data, TAs concentrations and DBT/phenanthrene ratios, the oils fall into four groups, reflecting different extents of source rock signal, alteration by TSR, mixing events, and secondary generation of H2S. Thermally stable TAs, that were produced following TSR, rapidly dominate kerogen-derived TAs at low to moderate degrees of TSR. Less thermally stable TLs and BTs were created as soon as TSR commenced, rapidly adopted TSR-δ34S values, but they do not survive at high concentrations unless TSR is advanced and ongoing. The presence of TLs and BTs shows that TSR is still active. Secondary DBTs were produced in significant amounts, sufficient to dominate kerogen-derived DBTs, only when TSR was at an advanced extent. The difference in sulfur isotopes between (i) TLs and DBTs and (ii) BTs and DBTs and (iii) TAs and DBTs, represents the extent of TSR while the presence of TAs at greater than 20 μg/g represents the occurrence of TSR. The output of this study shows that compound specific sulfur isotopes of different organosulfur compounds, with different thermal stabilities and formation pathways, not only differentiate between oils of TSR and non-TSR origin, but can also reveal information about relative timing of secondary charge events and migration pathways

Ca-signaling in airway smooth muscle cells is altered in T-bet knock-out mice

Background: Airway smooth muscle cells (ASMC) play a key role in bronchial hyperresponsiveness (BHR). A major component of the signaling cascade leading to ASMC contraction is calcium. So far, agonist-induced Ca2+-signaling in asthma has been studied by comparing innate properties of inbred rat or mouse strains, or by using selected mediators known to be involved in asthma. T-bet knock-out (KO) mice show key features of allergic asthma such as a shift towards T(H)2-lymphocytes and display a broad spectrum of asthma-like histological and functional characteristics. In this study, we aimed at investigating whether Ca2+-homeostasis of ASMC is altered in T-bet KO-mice as an experimental model of asthma. Methods: Lung slices of 100 to 200 mu m thickness were obtained from T-bet KO- and wild-type mice. Airway contraction in response to acetylcholine (ACH) was measured by video-microscopy and Ca2+-signaling in single ASMC of lung slices was assessed using two-photon-microscopy. Results: Airways from T-bet KO-mice showed increased baseline airway tone (BAT) and BHR compared to wild-type mice. This could be mimicked by incubation of lung slices from wild-type mice with IL-13. The increased BAT was correlated with an increased incidence of spontaneous changes in intracellular Ca2+-concentrations, whereas BHR correlated with higher ACH-induced Ca2+-transients and an increased proportion of ASMC showing Ca2+-oscillations. Emptying intracellular Ca2+-stores using caffeine or cyclopiazonic acid induced higher Ca2+-elevations in ASMC from T-bet KO- compared to wild-type mice. Conclusion: Altered Ca2+-homeostasis of ASMC contributes to increased BAT and BHR in lung slices from T-bet KO-mice as a murine asthma model. We propose that a higher Ca2+-content of the intracellular Ca2+-stores is involved in the pathophysiology of these changes

Lichenological exploration of Algeria: historical overview and annotated bibliography, 1799-2013

yesDespite more than two centuries of almost uninterrupted surveys and studies of Algerian lichenology, the history and lichen diversity of Algeria are still poorly understood. During the preparation of a forthcoming checklist of Algerian lichens it was considered necessary to provide the present historical overview of lichenological exploration of the country from 1799 to 2013, supported by a reasonably comprehensive annotated bibliography of 171 titles

Physical Fruit Traits in Moroccan Almond Seedlings: Quality Aspects and Post-Harvest Uses

The physical traits of local almond populations from Morocco were studied to characterize their genetic resources and to evaluate the possibility of their commercial valorization. Nut weight ranged between 1.15 and 7.39 g, and kernel weight between 0.54 and 1.85 g, but most accessions were characterized by small kernels, pronounced wrinkles, and double kernels. Although the physical quality of the kernels of these populations was low, they show the possibility of some specialized uses, which could improve their marketable value. The genotypes with favorable values could be incorporated into an almond breeding program as parents to increase the kernel quality.Publishe

Dynamic changes in eIF4F-mRNA interactions revealed by global analyses of environmental stress responses

BACKGROUND: Translation factors eIF4E and eIF4G form eIF4F, which interacts with the messenger RNA (mRNA) 5' cap to promote ribosome recruitment and translation initiation. Variations in the association of eIF4F with individual mRNAs likely contribute to differences in translation initiation frequencies between mRNAs. As translation initiation is globally reprogrammed by environmental stresses, we were interested in determining whether eIF4F interactions with individual mRNAs are reprogrammed and how this may contribute to global environmental stress responses. RESULTS: Using a tagged-factor protein capture and RNA-sequencing (RNA-seq) approach, we have assessed how mRNA associations with eIF4E, eIF4G1 and eIF4G2 change globally in response to three defined stresses that each cause a rapid attenuation of protein synthesis: oxidative stress induced by hydrogen peroxide and nutrient stresses caused by amino acid or glucose withdrawal. We find that acute stress leads to dynamic and unexpected changes in eIF4F-mRNA interactions that are shared among each factor and across the stresses imposed. eIF4F-mRNA interactions stabilised by stress are predominantly associated with translational repression, while more actively initiating mRNAs become relatively depleted for eIF4F. Simultaneously, other mRNAs are insulated from these stress-induced changes in eIF4F association. CONCLUSION: Dynamic eIF4F-mRNA interaction changes are part of a coordinated early translational control response shared across environmental stresses. Our data are compatible with a model where multiple mRNA closed-loop complexes form with differing stability. Hence, unexpectedly, in the absence of other stabilising factors, rapid translation initiation on mRNAs correlates with less stable eIF4F interactions

Cross-tolerance to abiotic stresses in halophytes: Application for phytoremediation of organic pollutants

International audienceHalopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes

LA PH- IMPEDANCEMETRIE ŒSOPHAGIENNE: NOUVELLE EXPLORATION DU RGO EN 2006

L’exploration fonctionnelle oesophagienne en matière de reflux gastro-oesophagien (RGO) a connu ces dernières années de nombreux progrès aussi bien en ce qui concerne la physiopathologie que le diagnostic de cette pathologie. Si la pH-métrie standard de 24 heures représente la technique de référence pour évaluer quantitativement le reflux acide et analyser la concordance épisode de reflux par rapport au symptôme, elle a néanmoins des limites en ce qui concerne le reflux non acide. La mesure de l’impédance électrique endo-luminale oesophagienne (MII-pH) est une nouvelle technique qui a révolutionnée actuellement la prise en charge du RGO, ouvrant de nouvelles perspectives diagnostiques et thérapeutiques