GRAVITY is a new instrument to coherently combine the light of the European Southern Observatory Very Large Telescope Interferometer to form a telescope with an equivalent 130 m diameter angular ...resolution and a collecting area of 200 m2. The instrument comprises fiber fed integrated optics beam combination, high resolution spectroscopy, built-in beam analysis and control, near-infrared wavefront sensing, phase-tracking, dual-beam operation, and laser metrology. GRAVITY opens up to optical/infrared interferometry the techniques of phase referenced imaging and narrow angle astrometry, in many aspects following the concepts of radio interferometry. This article gives an overview of GRAVITY and reports on the performance and the first astronomical observations during commissioning in 2015/16. We demonstrate phase-tracking on stars as faint as mK ≈ 10 mag, phase-referenced interferometry of objects fainter than mK ≈ 15 mag with a limiting magnitude of mK ≈ 17 mag, minute long coherent integrations, a visibility accuracy of better than 0.25%, and spectro-differential phase and closure phase accuracy better than 0.5°, corresponding to a differential astrometric precision of better than ten microarcseconds (μas). The dual-beam astrometry, measuring the phase difference of two objects with laser metrology, is still under commissioning. First observations show residuals as low as 50 μas when following objects over several months. We illustrate the instrument performance with the observations of archetypical objects for the different instrument modes. Examples include the Galactic center supermassive black hole and its fast orbiting star S2 for phase referenced dual-beam observations and infrared wavefront sensing, the high mass X-ray binary BP Cru and the active galactic nucleus of PDS 456 for a few μas spectro-differential astrometry, the T Tauri star S CrA for a spectro-differential visibility analysis, ξ Tel and 24 Cap for high accuracy visibility observations, and η Car for interferometric imaging with GRAVITY.
Context. The inner few au region of planet-forming disks is a complex environment. High angular resolution observations have a key role in understanding the disk structure and the dynamical processes ...at work. Aims. In this study we aim to characterize the mid-infrared brightness distribution of the inner disk of the young intermediate-mass star HD 163296, from VLTI/MATISSE observations. Methods. We use geometric models to fit the data. Our models include a smoothed ring, a flat disk with inner cavity, and a 2D Gaussian. The models can account for disk inclination and for azimuthal asymmetries as well. We also perform numerical hydro-dynamical simulations of the inner edge of the disk. Results. Our modeling reveals a significant brightness asymmetry in the L-band disk emission. The brightness maximum of the asymmetry is located at the NW part of the disk image, nearly at the position angle of the semimajor axis. The surface brightness ratio in the azimuthal variation is \(3.5 \pm 0.2\). Comparing our result on the location of the asymmetry with other interferometric measurements, we confirm that the morphology of the \(r<0.3\) au disk region is time-variable. We propose that this asymmetric structure, located in or near the inner rim of the dusty disk, orbits the star. For the physical origin of the asymmetry, we tested a hypothesis where a vortex is created by Rossby wave instability, and we find that a unique large scale vortex may be compatible with our data. The half-light radius of the L-band emitting region is \(0.33\pm 0.01\) au, the inclination is \({52^\circ}^{+5^\circ}_{-7^\circ}\), and the position angle is \(143^\circ \pm 3^\circ\). Our models predict that a non-negligible fraction of the L-band disk emission originates inside the dust sublimation radius for \(\mu\)m-sized grains. Refractory grains or large (\(\gtrsim 10\ \mu\)m-sized) grains could be the origin for this emission.
Eta Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models at different wavelengths suggest a central binary with a 5.54 yr period residing in its core. 2D ...and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary's wind penetrates the primary's wind creating a low-density cavity in it, with dense walls where the two winds interact. We aim to trace the inner ~5-50 au structure of Eta Car's wind-wind interaction, as seen through BrG and, for the first time, through the He I 2s-2p line. We have used spectro-interferometric observations with GRAVITY at the VLTI. Our modeling of the continuum allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio of 1.06 +/- 0.05 over a PA = 130 +/- 20 deg. Our CMFGEN modeling helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed BrG and He I lines. Chromatic images across BrG reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of He I 2s-2p served to constrain the 20 mas structure of the line-emitting region. The observed morphology of He I suggests that the secondary is responsible for the ionized material that produces the line profile. Both the BrG and the He I 2s-2p maps are consistent with previous hydrodynamical models of the colliding wind scenario. Future dedicated simulations together with an extensive interferometric campaign are necessary to refine our constraints on the wind and stellar parameters of the binary, which finally will help us predict the evolutionary path of Eta Car.
GRAVITY is a new instrument to coherently combine the light of the European Southern Observatory Very Large Telescope Interferometer to form a telescope with an equivalent 130 m diameter angular ...resolution and a collecting area of 200 m\(^2\). The instrument comprises fiber fed integrated optics beam combination, high resolution spectroscopy, built-in beam analysis and control, near-infrared wavefront sensing, phase-tracking, dual beam operation and laser metrology .... This article gives an overview of GRAVITY and reports on the performance and the first astronomical observations during commissioning in 2015/16. We demonstrate phase tracking on stars as faint as m\(_K\) ~ 10 mag, phase-referenced interferometry of objects fainter than m\(_K\) ~ 15 mag with a limiting magnitude of m\(_K\) ~ 17 mag, minute long coherent integrations, a visibility accuracy of better than 0.25 %, and spectro-differential phase and closure phase accuracy better than 0.5{\deg}, corresponding to a differential astrometric precision of better than 10 microarcseconds ({\mu}as). The dual-beam astrometry, measuring the phase difference of two objects with laser metrology, is still under commissioning. First observations show residuals as low as 50 {\mu}as when following objects over several months. We illustrate the instrument performance with the observations of archetypical objects for the different instrument modes. Examples include the Galactic Center supermassive black hole and its fast orbiting star S2 for phase referenced dual beam observations and infrared wavefront sensing, the High Mass X-Ray Binary BP Cru and the Active Galactic Nucleus of PDS 456 for few {\mu}as spectro-differential astrometry, the T Tauri star S CrA for a spectro-differential visibility analysis, {\xi} Tel and 24 Cap for high accuracy visibility observations, and {\eta} Car for interferometric imaging with GRAVITY.
MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant ...advances by opening new avenues in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 um, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R ~ 30 to R ~ 5000. Here, we present one of the main science objectives, the study of protoplanetary disks, that has driven the instrument design and motivated several VLTI upgrades (GRA4MAT and NAOMI). We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performances. We also discuss the current status of the MATISSE instrument, which is entering its testing phase, and the foreseen schedule for the next two years that will lead to the first light at Paranal.
Previously we have shown that supercritical carbon dioxide can be used to extract organics from ionic liquids (ILs). Subsequently, ionic liquids/carbon dioxide biphasic solutions have been used for a ...variety of homogeneously catalyzed reactions. Therefore, an understanding of the phase behavior of carbon dioxide with ionic liquids is needed to design extraction and reaction processes necessary for these applications. We present measurements of the solubility of carbon dioxide in 10 different imidazolium-based ionic liquids at 25, 40, and 60 °C and pressures to 150 bar. As expected, the solubility increases with increasing pressure and decreases with increasing temperature for all the ILs investigated. To investigate the influence of the anion, seven of the ILs studied have 1-butyl-3-methylimidazolium (bmim) as the cation. The anions are dicyanamide (DCA), nitrate (NO3), tetrafluoroborate (BF4), hexafluorophosphate (PF6), trifuoromethanesulfonate (TfO), bis(trifluoromethylsulfonyl)imide (Tf2N), and tris(trifluoromethylsulfonyl)methide (methide). The other ILs considered in the study, chosen to investigate the influence of varying number and length of alkyl chains on the cation, include 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (hmimTf2N), 2,3-dimethyl-1-hexylimidazolium bis(trifluoromethylsulfonyl)imide (hmmimTf2N), and 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (omimTf2N). Results show that the solubility of carbon dioxide is strongly dependent on the choice of anion. In particular, CO2 solubility is greater in ILs with anions, such as Tf2N and methide, which contain fluoroalkyl groups. Also, we observe that an increase in the alkyl chain length on the cation increases the CO2 solubility marginally.
Cyclo-oxygenase 2 (COX2)-selective inhibitors should reduce ulcer complications compared with non-selective non-steroidal anti-inflammatory drugs, but evidence is limited, and the possibility that ...these inhibitors increase cardiovascular events has been raised. The Therapeutic Arthritis Research and Gastrointestinal Event Trial (TARGET) aimed to assess gastrointestinal and cardiovascular safety of the COX2 inhibitor lumiracoxib compared with two non-steroidal anti-inflammatory drugs, naproxen and ibuprofen.
18 325 patients age 50 years or older with osteoarthritis were randomised to lumiracoxib 400 mg once daily (n=9156), naproxen 500 mg twice daily (4754), or ibuprofen 800 mg three times daily (4415) for 52 weeks, in two substudies of identical design (lumiracoxib
vs ibuprofen or naproxen). Randomisation was stratified for low-dose aspirin use and age. The primary endpoint was the difference in time-to-event distribution of upper gastrointestinal ulcer complications (bleeding, perforation, or obstruction); analysis was by modified intention to treat. The principle measure of adverse cardiovascular events was the Antiplatelet Trialists' Collaboration endpoint (myocardial infarction, stroke, or cardiovascular death); this analysis was intention to treat.
81 (0·44%) patients did not start treatment and 7120 (39%) did not complete the study. In patients not taking aspirin, the cumulative 1-year incidence of ulcer complications was 1·09% (95% CI 0·82–1·36) with non-steroidal anti-inflammatory drugs (64 events) versus 0·25% (95% CI 0·12–0·39) with lumiracoxib (14 events; hazard ratio 0·21 95% CI 0·12–0·37, p<0·0001). Reductions in ulcer complications were also significant in the overall population (0·34 0·22–0·52, p<0·0001) but not in those taking aspirin (0·79 0·40–1·55, p=0·4876). In the overall population, 0·55% (50/9127) of those on non-steroidal anti-inflammatory drugs and 0·65% (59/9117) of those on lumiracoxib reached the cardiovascular endpoint (1·14 0·78–1·66, p=0·5074).
Lumiracoxib showed a three to four-fold reduction in ulcer complications compared with non-steroidal anti-inflammatory drugs without an increase in the rate of serious cardiovascular events, suggesting that lumiracoxib is an appropriate treatment for patients with osteoarthritis.
The potential for cyclo-oxygenase 2 (COX2)-selective inhibitors to increase the risk for myocardial infarction is controversial. The Therapeutic Arthritis Research and Gastrointestinal Event Trial ...(TARGET) aimed to assess gastrointestinal and cardiovascular safety of the COX2 inhibitor lumiracoxib compared with two non-steroidal anti-inflammatory drugs, naproxen and ibuprofen.
18 325 patients age 50 years or older with osteoarthritis were randomised to lumiracoxib 400 mg once daily (n=9156), naproxen 500 mg twice daily (4754), or ibuprofen 800 mg three times daily (4415) in two substudies of identical design. Randomisation was stratified for low-dose aspirin use and age. The primary cardiovascular endpoint was the Antiplatelet Trialists' Collaboration endpoint of non-fatal and silent myocardial infarction, stroke, or cardiovascular death. Analysis was by intention to treat.
81 (0·44%) patients did not start treatment and 7120 (39%) did not complete the study. At 1-year follow-up, incidence of the primary endpoint was low, both with lumiracoxib (59 events 0·65%) and the non-steroidal anti-inflammatory drugs (50 events 0·55%; hazard ratio 1·14 95% CI 0·78–1·66, p=0·5074). Incidence of myocardial infarction (clinical and silent) in the overall population in the individual substudies was 0·38% with lumiracoxib (18 events) versus 0·21% with naproxen (ten) and 0·11% with lumiracoxib (five) versus 0·16% with ibuprofen (seven). In the naproxen substudy, rates of myocardial infarction (clinical and silent) did not differ significantly compared with lumiracoxib in the population not taking low-dose aspirin (hazard ratio 2·37 95% CI 0·74–7·55, p=0·1454), overall (1·77 0·82–3·84, p=0·1471), and in patients taking aspirin (1·36 0·47–3·93, p=0·5658). In the ibuprofen substudy, these rates did not differ between lumiracoxib and ibuprofen in the population not taking low-dose aspirin (0·75 0·20–2·79, p=0·6669), overall (0·66 0·21–2·09, p=0·4833), and in patients taking aspirin (0·47 0·04–5·14, p=0·5328).
The primary endpoint, including incidence of myocardial infarction, did not differ between lumiracoxib and either ibuprofen or naproxen, irrespective of aspirin use. This finding suggests that lumiracoxib is an appropriate treatment for patients with osteoarthritis, who are often at high cardiovascular risk and taking low-dose aspirin.
Gas solubility in ionic liquids Mellein, Berlyn R.; Scurto, Aaron M.; Shiflett, Mark B.
Current opinion in green and sustainable chemistry,
April 2021, 2021-04-00, Letnik:
28
Journal Article
Recenzirano
This update to the previous perspective summarizes recent work in the area of gas solubilities in ionic liquids over the last four years (2017–2020). As research into applications of ionic liquids, ...especially for gas separations, continues to gain momentum, the importance of understanding the gas + ionic liquid global phase behavior is paramount. The majority of experimental gas solubility studies tend to focus on classic methods like the gravimetric microbalance method and the stoichiometric pressure drop method. There continues to be a significant amount of work on modeling ionic liquids using correlative equation of state to simply model the thermodynamic behavior or purely predictive modeling such as molecular dynamics. The combination of these techniques can be a powerful tool for further understanding of the global phase behavior of gas + ionic liquid systems as well as the screening and/or task-specific design of ionic liquids for specific purposes.
Background: Evidence suggests that both selective cyclooxygenase (COX)-2 inhibitors and non-selective non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of cardiovascular events. ...However, evidence from prospective studies of currently available COX-2 inhibitors and non-selective NSAIDs is lacking in patients at high cardiovascular risk who are taking aspirin. Objective: To determine the cardiovascular outcomes in high risk patients with osteoarthritis treated with ibuprofen, naproxen or lumiracoxib. Methods: The Therapeutic Arthritis Research and Gastrointestinal Event Trial (TARGET) of 18 325 patients with osteoarthritis comprised two parallel substudies, comparing lumiracoxib (COX-2 inhibitor) with either ibuprofen or naproxen. A post hoc analysis by baseline cardiovascular risk, treatment assignment, and low-dose aspirin use was performed. The primary composite end point was cardiovascular mortality, non-fatal myocardial infarction, and stroke at 1 year; a secondary end point was the development of congestive heart failure (CHF). Results: In high risk patients among aspirin users, patients in the ibuprofen substudy had more primary events with ibuprofen than lumiracoxib (2.14% vs 0.25%, p = 0.038), whereas in the naproxen substudy rates were similar for naproxen and lumiracoxib (1.58% vs 1.48%, p = 0.899). High risk patients not taking aspirin had fewer primary events with naproxen than with lumiracoxib (0% vs 1.57%, p = 0.027), but not for ibuprofen versus lumiracoxib (0.92% vs 0.80%, p = 0.920). Overall, CHF developed more often with ibuprofen than lumiracoxib (1.28% vs 0.14%; p = 0.031), whereas no difference existed between naproxen and lumiracoxib. Conclusions: These data suggest that ibuprofen may confer an increased risk of thrombotic and CHF events relative to lumiracoxib among aspirin users at high cardiovascular risk. The study indicates that naproxen may be associated with lower risk relative to lumiracoxib among non-aspirin users. This study is subject to inherent limitations, and therefore should be interpreted as a hypothesis-generating study.
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