In order to mitigate the nitrate water pollution and nitrogenous gases emissions to the atmosphere, different types of highly swelling hydrogels based on acrylamide and itaconic acid have been ...prepared by using two different crosslinking agents: NMBA and EGDMA. Controlled release systems were evaluated by loading potassium nitrate into the hydrogels. The swelling and nitrate release kinetics were evaluated in Milli-Q water and saline medium, and various diffusion parameters were also calculated by applying the Ritger-Peppas equations, one of which modified by the authors for the diffusion process due to the innovative and non-described conical shape of the hydrogels used in this study. The hydrogels showed swelling and release characteristics highly dependent on their chemical composition and ionic strength of the medium, having the type of crosslinker the major impact on their behaviour, which can be related to the hydrophilic/hydrophobic characteristics of the crosslinkers. So, these hydrogels showed good potential applications for being used as soil conditioners and controlled release systems in agriculture.
Context.
Ultra-hot Jupiters are excellent laboratories for the study of exoplanetary atmospheres. WASP-121b is one of the most studied; many recent analyses of its atmosphere report interesting ...features at different wavelength ranges.
Aims.
In this paper we analyze one transit of WASP-121b acquired with the high-resolution spectrograph ESPRESSO at VLT in one-telescope mode, and one partial transit taken during the commissioning of the instrument in four-telescope mode.
Methods.
We take advantage of the very high S/N data and of the extreme stability of the spectrograph to investigate the anomalous in-transit radial velocity curve and study the transmission spectrum of the planet. We pay particular attention to the removal of instrumental effects, and stellar and telluric contamination. The transmission spectrum is investigated through single-line absorption and cross-correlation with theoretical model templates.
Results.
By analyzing the in-transit radial velocities we were able to infer the presence of the atmospheric Rossiter–McLaughlin effect. We measured the height of the planetary atmospheric layer that correlates with the stellar mask (mainly Fe) to be 1.052 ± 0.015
R
p
and we also confirmed the blueshift of the planetary atmosphere. By examining the planetary absorption signal on the stellar cross-correlation functions we confirmed the presence of a temporal variation of its blueshift during transit, which could be investigated spectrum-by-spectrum thanks to the quality of our ESPRESSO data. We detected significant absorption in the transmission spectrum for Na, H, K, Li, Ca
II
, and Mg, and we certified their planetary nature by using the 2D tomographic technique. Particularly remarkable is the detection of Li, with a line contrast of ~0.2% detected at the 6
σ
level. With the cross-correlation technique we confirmed the presence of Fe
I
, Fe
II
, Cr
I
, and V
I
. H
α
and Ca
II
are present up to very high altitudes in the atmosphere (~1.44
R
p
and ~2
R
p
, respectively), and also extend beyond the transit-equivalent Roche lobe radius of the planet. These layers of the atmosphere have a large line broadening that is not compatible with being caused by the tidally locked rotation of the planet alone, and could arise from vertical winds or high-altitude jets in the evaporating atmosphere.
Revisiting Proxima with ESPRESSO Suárez Mascareño, A.; Faria, J. P.; Figueira, P. ...
Astronomy & astrophysics,
07/2020, Letnik:
639
Journal Article
Recenzirano
Odprti dostop
Context.
The discovery of Proxima b marked one of the most important milestones in exoplanetary science in recent years. Yet the limited precision of the available radial velocity data and the ...difficulty in modelling the stellar activity calls for a confirmation of the Earth-mass planet.
Aims.
We aim to confirm the presence of Proxima b using independent measurements obtained with the new ESPRESSO spectrograph, and refine the planetary parameters taking advantage of its improved precision.
Methods.
We analysed 63 spectroscopic ESPRESSO observations of Proxima (Gl 551) taken during 2019. We obtained radial velocity measurements with a typical radial velocity photon noise of 26 cm s
−1
. We combined these data with archival spectroscopic observations and newly obtained photometric measurements to model the stellar activity signals and disentangle them from planetary signals in the radial velocity (RV) data. We ran a joint Markov chain Monte Carlo analysis on the time series of the RV and full width half maximum of the cross-correlation function to model the planetary and stellar signals present in the data, applying Gaussian process regression to deal with the stellar activity signals.
Results.
We confirm the presence of Proxima b independently in the ESPRESSO data and in the combined ESPRESSO+ HARPS+UVES dataset. The ESPRESSO data on its own shows Proxima b at a period of 11.218 ± 0.029 days, with a minimum mass of 1.29 ± 0.13
M
⊕
. In the combined dataset we measure a period of 11.18427 ± 0.00070 days with a minimum mass of 1.173 ± 0.086
M
⊕
. We get a clear measurement of the stellar rotation period (87 ± 12 d) and its induced RV signal, but no evidence of stellar activity as a potential cause for the 11.2 days signal. We find some evidence for the presence of a second short-period signal, at 5.15 days with a semi-amplitude of only 40 cm s
−1
. If caused by a planetary companion, it would correspond to a minimum mass of 0.29 ± 0.08
M
⊕
. We find that forthe case of Proxima, the full width half maximum of the cross-correlation function can be used as a proxy for the brightness changes and that its gradient with time can be used to successfully detrend the RV data from part of the influence of stellar activity. The activity-induced RV signal in the ESPRESSO data shows a trend in amplitude towards redder wavelengths. Velocities measured using the red end of the spectrograph are less affected by activity, suggesting that the stellar activity is spot dominated. This could be used to create differential RVs that are activity dominated and can be used to disentangle activity-induced and planetary-induced signals. The data collected excludes the presence of extra companions with masses above 0.6
M
⊕
at periods shorter than 50 days.
Summary Systematic review of adherence to bisphosphonates for the treatment of osteoporosis finds suboptimal levels of persistence and compliance. Poor bisphosphonate compliance increases fracture ...risk. Introduction The objectives of the study were to measure the persistence and compliance with bisphosphonates for the treatment of osteoporotic patients, and to estimate the influence of compliance on fracture risk. Methods A systematic review of bisphosphonate adherence in clinical practise provided new evidence to perform a meta-analysis of the means of bisphosphonate persistence and compliance, with a subsequent meta-analysis of fracture risk comparing poorly versus highly compliant patients. Results Fifteen articles, totalling 704,134 patients, met our inclusion criteria. Most of the patients were postmenopausal women treated with bisphosphonates. The 3.95% of the patients received hormone replacement therapy, but the rest received bisphosphonates. The meta-analysis of five articles totalling 236,540 patients, who were followed for 1 year, provided a pooled persistence mean of 184.09 days. The meta-analysis of five articles, totalling 234,737 patients, who were also followed for 1 year, provided a pooled medication possession ratio mean of 66.93%. The meta-analysis of six articles, totalling 171,063 patients, who were followed for varying periods of time between 1 and 2.5 years, provided a pooled 46% increased fracture risk in non-compliant patients versus compliant patients. The increased fracture risk was lower for non-vertebral (16%) and hip (28%) than for clinical vertebral fractures (43%). Conclusions Persistence and compliance are suboptimal for postmenopausal women undergoing bisphosphonate therapy for osteoporosis. The clinical consequence of this low compliance is an increased risk of fracture, which is lower for non-vertebral than for clinical vertebral fractures.
Context.
The study of exoplanet atmospheres is essential for understanding the formation, evolution, and composition of exoplanets. The transmission spectroscopy technique is playing a significant ...role in this domain. In particular, the combination of state-of-the-art spectrographs at low- and high-spectral resolution is key to our understanding of atmospheric structure and composition.
Aims.
We observed two transits of the close-in sub-Saturn-mass planet, WASP-127b, with ESPRESSO in the frame of the Guaranteed Time Observations Consortium. We aim to use these transit observations to study the system architecture and the exoplanet atmosphere simultaneously.
Methods.
We used the Reloaded Rossiter-McLaughlin technique to measure the projected obliquity
λ
and the projected rotational velocity
v
eq
⋅sin(
i
*
). We extracted the high-resolution transmission spectrum of the planet to study atomic lines. We also proposed a new cross-correlation framework to search for molecular species and we applied it to water vapor.
Results.
The planet is orbiting its slowly rotating host star (
v
eq
⋅sin(
i
*
) = 0.53
−0.05
+0.07
km s
−1
) on a retrograde misaligned orbit (
λ
= −128.41
−5.46
+5.60
°). We detected the sodium line core at the 9-
σ
confidence level with an excess absorption of 0.34 ± 0.04%, a blueshift of 2.74 ± 0.79 km s
−1
, and a full width at half maximum of 15.18 ± 1.75 km s
−1
. However, we did not detect the presence of other atomic species but set upper limits of only a few scale heights. Finally, we put a 3-
σ
upper limit on the average depth of the 1600 strongest water lines at equilibrium temperature in the visible band of 38 ppm. This constrains the cloud-deck pressure between 0.3 and 0.5 mbar by combining our data with low-resolution data in the near-infrared and models computed for this planet.
Conclusions.
WASP-127b, with an age of about 10 Gyr, is an unexpected exoplanet by its orbital architecture but also by the small extension of its sodium atmosphere (~7 scale heights). ESPRESSO allows us to take a step forward in the detection of weak signals, thus bringing strong constraints on the presence of clouds in exoplanet atmospheres. The framework proposed in this work can be applied to search for molecular species and study cloud-decks in other exoplanets.
Context.
The bright star
π
Men was chosen as the first target for a radial velocity follow-up to test the performance of ESPRESSO, the new high-resolution spectrograph at the European Southern ...Observatory’s Very Large Telescope. The star hosts a multi-planet system (a transiting 4
M
⊕
planet at ~0.07 au and a sub-stellar companion on a ~2100-day eccentric orbit), which is particularly suitable for a precise multi-technique characterization.
Aims.
With the new ESPRESSO observations, which cover a time span of 200 days, we aim to improve the precision and accuracy of the planet parameters and search for additional low-mass companions. We also take advantage of the new photometric transits of
π
Men c observed by TESS over a time span that overlaps with that of the ESPRESSO follow-up campaign.
Methods.
We analysed the enlarged spectroscopic and photometric datasets and compared the results to those in the literature. We further characterized the system by means of absolute astrometry with H
IPPARCOS
and
Gaia
. We used the high-resolution spectra of ESPRESSO for an independent determination of the stellar fundamental parameters.
Results.
We present a precise characterization of the planetary system around
π
Men. The ESPRESSO radial velocities alone (37 nightly binned data with typical uncertainty of 10 cm s
−1
) allow for a precise retrieval of the Doppler signal induced by
π
Men c. The residuals show a root mean square of 1.2 m s
−1
, which is half that of the HARPS data; based on the residuals, we put limits on the presence of additional low-mass planets (e.g. we can exclude companions with a minimum mass less than ~2
M
⊕
within the orbit of
π
Men c). We improve the ephemeris of
π
Men c using 18 additional TESS transits, and, in combination with the astrometric measurements, we determine the inclination of the orbital plane of
π
Men b with high precision (
i
b
=45.8
−1.1
+1.4
deg). This leads to the precise measurement of its absolute mass
m
b
=14.1
−0.4
+0.5
M
Jup
, indicating that
π
Men b can be classified as a brown dwarf.
Conclusions.
The
π
Men system represents a nice example of the extreme precision radial velocities that can be obtained with ESPRESSO for bright targets. Our determination of the 3D architecture of the
π
Men planetary system and the high relative misalignment of the planetary orbital planes put constraints on and challenge the theories of the formation and dynamical evolution of planetary systems. The accurate measurement of the mass of
π
Men b contributes to make the brown dwarf desert a bit greener.
This study examined the time-course effects (2, 7, 14 and 30 days) of acute chlorpyrifos (CPF) intoxication (250
mg/kg, s.c.) on monoamine systems and acetylcholinesterase (AChE) activity in the ...striatum and nucleus accumbens of adult male rats. We show that CPF produced significant long-term inhibition of AChE activity in the striatum and nucleus accumbens. In the striatum, CPF intoxication resulted in changes in dopamine (DA) metabolism after 2 days and changes in serotonin (5-HT) turnover after 7 and 15 days. Significant decreases in monoamine content including norepinephrine (NE), DA, 5-HT and their metabolites were found in the nucleus accumbens 30 days after CPF intoxication. These results suggest that acute exposure to CPF induces long-term changes in the monoamine systems (NE, DA and 5-HT) in adult animals. The lack of correlation between regional AChE activity and neurochemical outcomes points to independent mechanisms.
The sorption–desorption of the cationic pesticide 1,1′-dimethyl-4,4′-bipyridinium dichloride (paraquat) on a bentonite from Maghnia (Algeria) desiccated at 110°C (M), and calcined at 400°C (M400) and ...600°C (M600) from aqueous solution at 25°C has been studied using batch experiments. A complete characterization of the natural and heat activated bentonite samples has been carried out through the following techniques: X-ray fluorescence spectroscopy, FTIR, X-ray diffraction, thermogravimetric and differential thermogravimetric analysis and surface analysis. In order to have a better understanding of the variables affecting the sorption of this herbicide, factors such as the working temperature or the ionic strength of the solution have been investigated. The sorption experimental data have been fitted to the Langmuir equation in order to calculate the maximum sorption capacities (Xm) of the samples. The results show that the sorption capacity of the calcined samples greatly decreased with heat treatment. On the other hand, the sorption process is hardly affected by the working temperature, whereas the higher electrolyte concentration, the lower sorption of this pesticide. In addition to batch experiments, a decontamination continuous process (DCP) was designed by the authors using the natural clay to evaluate the potential application of this adsorbent for removing paraquat from water.
•Natural Algerian clay is most effective in removing paraquat than heat-treated sample.•Paraquat sorption is not affected by work temperature.•The presence of KCl in the medium decreases the amount of paraquat retained.•A novel decontamination continuous process for the purification of contaminated water
The adsorption of chloridazon on heat treated sepiolite samples at 110
°C (S-110), 200
°C (S-200), 400
°C (S-400), 600
°C (S-600) and acid treated samples with H
2SO
4 solutions of two different ...concentrations (0.25 and 1.0
M) (S-0.25 and S-1.0, respectively) from pure water at 25
°C has been studied by using batch experiments. In addition, column experiments were carried out with the natural (S-110) and 600
°C (S-600) heat treated samples, using a 10.30
mg
l
−1 aqueous solution of chloridazon. The adsorption experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (
K
f) of the samples;
K
f values range from 2.89
mg
kg
−1 for the S-1.0 sample up to 164
mg
kg
−1 for the S-600 sample; so, the heat treatment given to the sepiolite greatly increases its adsorption capacity for the herbicide chloridazon whereas the acid treatment produces a clear decrease in the amount of chloridazon adsorbed. The removal efficiency (
R) has also been calculated;
R values ranging from 5.08% for S-1.0 up to 60.9% for S-600. The batch experiments showed that the strongest heat treatment is more effective than the natural and acid treated sepiolite in relation to adsorption of chloridazon. The column experiments also showed that 600
°C heat treated sepiolite might be reasonably used in removing chloridazon from water. Thus, as this type of clay is relatively plentiful, these activated samples might be reasonably used in order to remove chloridazon from water.
Chlorpyrifos (CPF) is a common organophosphate (OP) insecticide that has been widely used in agriculture as a pesticide. The primary mechanism of acute toxic action of OPs is initiated by ...acetylcholinesterase (AChE) inhibition. However, non-AChE targets have also been proposed as alternative that contributes to the acute lethal action and side effects of short or long-term exposure. Recently, we have found that a single dose of 250 mg/kg CPF produces acceleration in acquisition on schedule-induced polydipsia (SIP) procedure 6 months after its administration. Moreover, CPF animals show a higher level of impulsivity in a delay-discounting task 1 year after acute administration, and these effects are potentiated when animals are divided into high (HD) and low (LD) drinkers in SIP. In the present study, rats were injected with a subcutaneous (sc) dose of 250 mg/kg of CPF, and 10 weeks later its effect on delay-discounting task was evaluated. Consequently, these animals were evaluated based on SIP, and divided into two populations (HD and LD) according to their rates of drinking in this task. One year after OP administration, these animals were re-evaluated in a delay-discounting task. Results revealed that the CPF-administered rats prefer immediate reward and show a more impulsive choice, 10 weeks after CPF administration. Furthermore, 1 year after it administration, only animals treated with CPF that are high drinkers on SIP are more impulsive than the rest of the groups Therefore, these data suggest that some individuals are more sensitive to OP intoxication than the others, at least in terms of durability of sequelae.