SUB-OCEAN: subsea dissolved methane measurements using an embedded laser spectrometer technology

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Environmental Science and Technology, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.est.7b06171.We present a novel instrument, the Sub-Ocean probe, allowing in situ and continuous measurements of dissolved methane in seawater. It relies on an optical feedback cavity enhanced absorption technique designed for trace gas measurements and coupled to a patent-pending sample extraction method. The considerable advantage of the instrument compared with existing ones lies in its fast response time of the order of 30 s, that makes this probe ideal for fast and continuous 3D-mapping of dissolved methane in water. It could work up to 40 MPa of external pressure and it provides a large dynamic range, from subnmol of CH4 per liter of seawater to mmol L-1. In this work, we present laboratory calibration of the instrument, intercomparison with standard method and field results on methane detection. The good agreement with the headspace equilibration technique followed by gas-chromatography analysis supports the utility and accuracy of the instrument. A continuous 620-m depth vertical profile in the Mediterranean Sea was obtained within only 10 min and it indicates background dissolved CH4 values between 1 and 2 nmol L-1 below the pycnocline, similar to previous observations conducted in different ocean settings. It also reveals a methane maximum at around 6 m of depth that may reflect local production from bacterial transformation of dissolved organic matter

Simultaneous cavity-enhanced and cavity ringdown absorption spectroscopy using optical feedback

International audienceWe present a scheme of optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) including a fast optical switch to produce cavity ringdown spectra (OF-CRDS) simultaneously. This also works as a dynamically adjustable variable attenuator allowing to compensate for reduced signal levels in correspondence with absorption lines. For this, an acousto-optic deflector is used in a double-pass configuration to eliminate the single-pass frequency shift, which is incompatible with optical feedback. This is probably the most effective device providing the required fast response and the high extinction ratio necessary to perform clean ringdown measurements. The resulting direct comparison of OF-CEAS and OF-CRDS shows that these produce almost equivalent spectral data, with 0.3 % maximal difference at the top of an absorption line having a signal-to-noise ratio (S/N) of 3,300. OF-CEAS is largely winning on the short-term noise level while OF-CRDS appears to be more immune from interference fringes, delivering cleaner spectra after longer averaging

Molecular Laser Spectroscopy as a Tool for Gas Analysis Applications

We have used the traceable infrared laser spectrometric amount fraction measurement (TILSAM) method to perform absolute concentration measurements of molecular species using three laser spectroscopic techniques. We report results performed by tunable diode laser absorption spectroscopy (TDLAS), quantum cascade laser absorption spectroscopy (QCLAS), and cavity ring down spectroscopy (CRDS), all based on the TILSAM methodology. The measured results of the different spectroscopic techniques are in agreement with respective gravimetric values, showing that the TILSAM method is feasible with all different techniques. We emphasize the data quality objectives given by traceability issues and uncertainty analyses

SPECIES: a versatile spectrometer based on optical-feedback cavity-enhanced absorption for in situ balloon-borne and airborne measurements

International audienceOver the last twenty years, thanks to significant technological advances in measurement techniques, our understanding of the chemistry and dynamics of the upper troposphere and stratosphere has progressed significantly. However some key questions remain unsolved, and new ones arise in the changing climate context. The full recovery of the ozone layer and the delay of recovery, the impact of the climate change on the stratosphere and the role of this one as a feedback are almost unknown. To address these challenges, one needs instruments able to measure a wide variety of trace gas species simultaneously with a wide vertical range. In this context, LPC2E and LIPHY are developing a new balloon-borne and airborne instrument: SPECIES (SPECtromètre Infrarouge à lasErs in Situ, i.e. in-Situ Infrared lasEr SPECtrometer). Based on the Optical Feedback Cavity Enhanced Spec-troscopy technique, combined with mid-infrared quantum cascade lasers, this instrument will offer unprecedented performances in terms of the vertical extent of the measurements, from ground to the middle stratosphere, and the number of molecular species simultaneously measured with sub-ppb detection limits (among others: NO, N2O, HNO 3 , H 2 O 2 , HCl, HOCl, CH3Cl, COF2, HCHO, HCOOH, O 3 , NH3 NO 2 , H 2 O, OCS, SO 2). Due to high frequency measurement (>0.5 Hz) it shall offer very high spatial resolution (a few meters)

Lower Relapses Rate With Infliximab Versus Adalimumab in Sight-Threatening Uveitis: A Multicenter Study of 330 Patients

International audiencePurpose: To compare the relapse rate of sight-threatening noninfectious uveitis (NIU) in patients treated with infliximab (IFX) or adalimumab (ADA).Design: Observational retrospective multicenter study.Methods: A total of 330 patients (median age, 36 years; interquartile range, 27-54), 45.2% men) with sight-threatening NIU (ie, retinal vasculitis and/or macular edema) treated with anti-tumor necrosis factor [TNF]-α agents (IFX intravenously at 5 mg/kg at weeks 0, 2, 6, and every 4 to 6 weeks or ADA subcutaneously at 80 mg, then 40 mg every 2 weeks). Data were obtained retrospectively from patients' medical records. Main outcome measures were relapse rate, complete response of NIU, corticosteroid sparing effect, and safety.Results: Main etiologies of uveitis included Behçet disease (27%), idiopathic juvenile arthritis (5.8%), and sarcoidosis (5.5%). The estimated relapse rate at 6 months after introduction of biological agents was 13% (95% CI = 0.009-0.16). IFX was associated with less relapse risk than ADA (hazard ratio [HR] = 0.52, 95% CI = 0.36- 0.77, P = .001). ADA and IFX were comparable in terms of complete response rate of NIU as well as corticosteroid-sparing effect. Behçet disease was associated with higher odds of complete response (HR = 2.04, 95% CI = 1.16 -3.60, P = .01] and lower relapse rate (HR = 0.53, 95% CI = 0.33-0.85, P = .009) than other causes of NIU with anti-TNF-α agents.Conclusions: In sight-threatening NIU, IFX seems to be associated with a lower relapse rate than ADA

A leader in an emerging new international market: the determinants of French wine exports, 1848–1938

The objective of this article is to provide an in-depth study of France''s performance in the new international wine market that began to take shape from the middle of the nineteenth century. We analyse the main determinants of its success in exporting ordinary and high-quality wine using a gravity model for both types of wine. The article shows how France lost foreign markets in the ordinary wine sector, due to difficulties in maintaining its exports, which resulted from the decrease in production caused by the phylloxera plague and increasing competition from growing numbers of producers who were more efficient at producing these types of wines. However, in the high-quality wine market, French exporters enjoyed considerable success, increasing their exports thanks to their efforts to offer a product that was highly valued abroad and the use of modern marketing and sales techniques. The exports benefited from the fall in transport costs and French colonial expansion. However, exports of both products were severely affected by a series of major events, including the First World War, the Russian Revolution, Prohibition in the US, and the Great Depression. This case study of the wine market shows that the collapse of the first globalization was not the same for all products