SO2 from volcanic eruptions is now operationally monitored from space in both the ultraviolet (UV) and thermal infrared (TIR) spectral range, but anthropogenic SO2 has almost solely been measured ...from UV sounders. Indeed, TIR instruments are well known to have a poor sensitivity to the planetary boundary layer (PBL), due to generally low thermal contrast (TC) between the ground and the air above it. Recent studies have demonstrated the capability of the Infrared Atmospheric Sounding Interferometer (IASI) to measure near-surface SO2 locally, for specific atmospheric conditions. In this work, we develop a retrieval method allowing the inference of SO2 near-surface concentrations from IASI measurements at a global scale. This method consists of two steps. Both are based on the computation of radiance indexes representing the strength of the SO2 ν3 band in IASI spectra. The first step allows the peak altitude of SO2 to be retrieved and near-surface SO2 to be selected. In the second step, 0–4 km columns of SO2 are inferred using a look-up table (LUT) approach. Using this new retrieval method, we obtain the first global distribution of near-surface SO2 from IASI-A, and identify the dominant anthropogenic hotspot sources and volcanic degassing. The 7-year daily time evolution of SO2 columns above two industrial source areas (Beijing in China and Sar Cheshmeh in Iran) is investigated and correlated to the seasonal variations of the parameters that drive the IASI sensitivity to the PBL composition. Apart from TC, we show that humidity is the most important parameter which determines IR sensitivity to near-surface SO2 in the ν3 band. As IASI provides global measurements twice daily, the differences between the retrieved columns for the morning and evening orbits are investigated. This paper finally presents a first intercomparison of the measured 0–4 km columns with an independent iterative retrieval method and with observations of the Ozone Monitoring Instrument (OMI).
Hydrophobic ionic liquids containing 1-butyl-2,3-dimethylpyridinium B2M3MPYR, 1-butyl-3,5-dimethylpyridinium B3M5MPYR, 1-butyl-2-methyl-5-ethylpyridinium B2M5EPYR, 1-butyl-2,3,5-trimethylpyridinium ...B2M3M5MPYR, 1-octyl-2,3-dimethylpyridinium O2M3MPYR, 1-octyl-3,5-dimethylpyridinium O3M5MPYR, 1-octyl-2-methyl-5-ethylpyridinium O2M5EPYR, or 1-octyl-2,3,5-trimethylpyridinium O2M3M5MPYR as the cation and bis(trifluoromethanesulfonyl)imide NTf2, trifluoromethanesulfonate TfO, dicyanamide N(CN)2, thiocyanate SCN or iodide as the anion have been synthesized, and their physicochemial properties have been studied. Thermal properties, solubilities in water and water contents, UV−vis spectra, densities, refractive indices, electrochemical windows, and toxicities on Vibrio fischeri have been measured. These ionic liquids, most of which are liquid at room temperature, exhibit high refractive indices and increased hydrophobicity. Despite high toxicity values toward V. fischeri, ionic liquids containing a dialkylpyridinium or trialkylpyridinium cation with an octyl chain represent good alternatives to extracting solvents.
Nosocomial case (NC) of COVID-19 infections is a challenge for hospitals. We report the results of a seven-month prospective cohort study investigating COVID-19 patients to assess unexpected cases ...(UC) (no COVID-19 precautionary measure application since admission) and NC.
Investigation by an infection control team of 844 patients with COVID-19 infection hospitalized for more than 24 hours (cases).
A total of 301 UC were identified (31% after contact tracing) with a total of 129 contact patients, and 27 secondary cases for 59 of them. In geriatric wards, 50% of cases were UC. NC represented 18% of cases (37% in geriatric wards), mainly identified after contact tracing of wandering cases.
A rapid infection control response is essential to contain nosocomial transmission, along with detailed contact tracing and screening policy. Dealing with wandering elderly patients remain challenging for HCWs.
Emission of volcanic gas is thought to be the dominant process by which volatiles transit from the deep earth to the atmosphere. Volcanic gas emissions, remain poorly constrained, and volcanoes of ...Peru are entirely absent from the current global dataset. In Peru, Sabancaya and Ubinas volcanoes are by far the largest sources of volcanic gas. Here, we report the first measurements of the compositions and fluxes of volcanic gases emitted from these volcanoes. The measurements were acquired in November 2015. We determined an average SO2 flux of 15.3±2.3kgs−1 (1325-tonday−1) at Sabancaya and of 11.4±3.9kgs−1 (988-tonday−1) at Ubinas using scanning ultraviolet spectroscopy and dual UV camera systems. In-situ Multi-GAS analyses yield molar proportions of H2O, CO2, SO2, H2S and H2 gases of 73, 15, 10 1.15 and 0.15mol% at Sabancaya and of 96, 2.2, 1.2 and 0.05mol% for H2O, CO2, SO2 and H2S at Ubinas. Together, these data imply cumulative fluxes for both volcanoes of 282, 30, 27, 1.2 and 0.01kgs−1 of H2O, CO2, SO2, H2S and H2 respectively. Sabancaya and Ubinas volcanoes together contribute about 60% of the total CO2 emissions from the Central Volcanic zone, and dominate by far the total revised volatile budget of the entire Central Volcanic Zone of the Andes.
•First characterization of plume composition at Sabancaya and Ubinas volcanoes•Volatile flux from the CVZ is nearly three time higher than previously estimated.•Intense and periodic degassing activity at Sabancaya attested to probable magma convection at shallow depth.
We consider the class of surfactants called “extractants” since they specifically interact with some cations and are used in liquid-liquid separation processes. We review here features of water-poor ...reverse micelles in water/oil/ extractant systems as determined by combined structural studies including small angle scattering techniques on absolute scale. Origins of instabilities, liquid-liquid separation as well as emulsification failure are detected. Phase diagrams contain the same multi-phase domains as classical microemulsions, but special unusual features appear due to the high spontaneous curvature directed towards the polar cores of aggregates as well as rigidity of the film made by extracting molecules.
Cystic fibrosis (CF) patients are at particularly high risk of developing lung disease caused by Mycobacterium abscessus complex (MABSC). Over the last 10 years, changes in CF treatment, with ...increasing use of inhaled therapies and low-dose azithromycin, have been accompanied by an increase in the prevalence of MABSC infections in CF patients. There is therefore some concern about the role of new CF treatments in the emergence of MABSC infections. We addressed this issue by means of a case-control study including 30 MABSC-positive cases and 60 nontuberculous mycobacteria-negative CF controls matched for age, sex and centre. We also compared practices at the CF centres with the highest prevalence of MABSC with those at the other centres. No positive association was found between MABSC lung disease and the use of inhaled therapies or low-dose azithromycin in the 4 years preceding MABSC isolation. These treatments were not significantly more frequently used at the CF centres with the highest MABSC prevalence rates. In conclusion, there is no evidence for a link between M. abscessus complex lung disease and inhaled therapies or low-dose azithromycin in patients with CF.
It has been suggested that dust storms efficiently transport water vapor from the near‐surface to the middle atmosphere on Mars. Knowledge of the water vapor vertical profile during dust storms is ...important to understand water escape. During Martian Year 34, two dust storms occurred on Mars: a global dust storm (June to mid‐September 2018) and a regional storm (January 2019). Here we present water vapor vertical profiles in the periods of the two dust storms (Ls = 162–260° and Ls = 298–345°) from the solar occultation measurements by Nadir and Occultation for Mars Discovery (NOMAD) onboard ExoMars Trace Gas Orbiter (TGO). We show a significant increase of water vapor abundance in the middle atmosphere (40–100 km) during the global dust storm. The water enhancement rapidly occurs following the onset of the storm (Ls~190°) and has a peak at the most active period (Ls~200°). Water vapor reaches very high altitudes (up to 100 km) with a volume mixing ratio of ~50 ppm. The water vapor abundance in the middle atmosphere shows high values consistently at 60°S‐60°N at the growth phase of the dust storm (Ls = 195°–220°), and peaks at latitudes greater than 60°S at the decay phase (Ls = 220°–260°). This is explained by the seasonal change of meridional circulation: from equinoctial Hadley circulation (two cells) to the solstitial one (a single pole‐to‐pole cell). We also find a conspicuous increase of water vapor density in the middle atmosphere at the period of the regional dust storm (Ls = 322–327°), in particular at latitudes greater than 60°S.
Plain Language Summary
The most striking phenomenon on Mars is a planet‐encircling storm, “global dust storm.” Once it starts, the floating dust covers the whole atmosphere for more than several weeks. Recent studies suggest that dust storms effectively transport water vapor from the near‐surface to the middle atmosphere. In June to September 2018 and January 2019, a strong global dust storm and a regional storm occurred on Mars, respectively. This study investigates altitude profiles of water vapor in the Mars atmosphere measured during the dust storms, by using brand‐new measurements by Nadir and Occultation for Mars Discovery onboard the ExoMars Trace Gas Orbiter. We confirm that the water vapor expanded into the middle atmosphere, and we find that the water vapor reached very high altitudes (up to 100 km) during the dust storms. The dust storms intensify the atmospheric dynamics and heat the atmosphere. As a result, water vapor is lifted to higher altitudes and distributes along the meridional circulation.
Key Points
We present vertical profiles of water vapor in the Martian atmosphere during global and regional dust storms in 2018‐2019
We show a rapid and significant increase of water vapor in the middle atmosphere (40‐100 km) during both global and regional dust storms
Water vapor reaches very high altitudes, at least around 100 km, during the global dust storm
Because of their amphiphilic structure, surfactants adsorb at the water–air interface with their hydrophobic tails pointing out of the water and their polar heads plunging into the liquid phase. ...Unlike classical surfactants, metallabisdicarbollides (MCs) do not have a well-defined amphiphilic structure. They are nanometer-sized inorganic anions with an ellipsoidal shape composed of two carborane semicages sandwiching a metal ion. However, MCs have been shown to share many properties with surfactants, such as self-assembly in water (formation of micelles and vesicles), formation of lamellar lyotropic phases, and surface activity. By combining second harmonic generation and surface tension measurement, we show here that cobaltabis(dicarbollide) anion {(C2B9H11)2Co− also named COSAN−} with H+ as a counterion, the most representative metallacarborane, adsorbs vertically at the water surface with its long axis normal to the surface. This vertical molecular orientation facilitates the formation of intermolecular and nonconventional dihydrogen bonds such as the B–Hδ−···δ+H–C bond that has recently been proven to be at the origin of the self-assembly of MCs in water. Therefore, it appears here that lateral dihydrogen bonds are also involved in the surface activity of MCs.
Background In France about 32% of hospitalized patients have a vascular access placement. However, a common complication associated with these is catheter-related bloodstream infection (CRBI) due to ...the introduction of microorganisms from the skin during catheter insertion. There is no consensus on the best way to clean the skin prior to catheter insertion, which could be a key element of CRBI prevention. The two techniques most commonly used to apply antiseptic to the skin are the concentric circle and back-and-forth techniques, but these have not been compared in clinical trials. Hence, this study conducted this comparison. Methods This single-center, non-comparative, randomized, matched pilot study investigated the levels of cutaneous microorganisms before and after antiseptic application using both techniques in a population of healthy French volunteers. The two application methods were used on each participant's arms at the elbow fold, with randomization for the application side (right or left). Quantification of cutaneous microorganisms was performed in a blinded manner with regard to the technique used. Findings From April 8 to July 17, 2019, 132 healthy volunteers participated in the study. For the whole study population, the mean initial colonization level was 2.68 log10 colony forming units (CFU)/mL (SD 0.82) before the back-and-forth technique, and 2.66 log10 CFU/mL (SD 0.85) before the concentric circle technique. The mean differences in number of microorganisms between the initial sample and the final sample were 2.45 log10 CFU/mL (95% CI: 2.29 to 2.61) for the back-and-forth technique and 2.43 log10 CFU/mL (95% CI: 2.27 to 2.59) for the concentric circle technique. The mean difference in reduction in microorganisms between the back-and-forth technique and the concentric circle technique was 0.02 log10 CFU/mL (95% CI: –0.11 to 0.15). Interpretation There was no clinically difference in reduction of microorganisms between the concentric circle and back-and-forth techniques at the bend of the healthy volunteer's elbow, after the 30 s of drying of the antiseptic. These findings have a significant impact on time required to achieve antiseptic application before catheter insertion because there is yet no argument to justify application for 30 s, because a single concentric circle pass was much faster with similar results. Future studies should investigate the impact of skin application technique on the prevention of infectious risk associated with catheter insertion on admission to health care facilities (conventional, outpatient, or emergency) and throughout the period of stay in a health care facility.
PDF
