8 resultados para 17B
Resumo:
We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses, but 1.5-2 Jupiter radii, giving a density of 6%-14% that of Jupiter. WASP-17b is in a 3.7 day orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a retrograde orbit (? ˜ -150°), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularization of an eccentric orbit, such as the highly eccentric orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.
Resumo:
Suitable ester prodrugs of 17b-estradiol are identified, thus permitting effective sustained and controlled estrogen replacement therapy (ERT) from an elastomeric, silicone intravaginal ring (IVR). IVR devices of reservoir design were prepared by blending silicone elastomer base with n-propylorthosilicate (cross-linker) and 10% w/w of 17b-estradiol or an ester prodrug, the mix being activated with 0.5% w/w stannous octoate and cured at 808C for 2 min. A rate-controlling membrane was similarly prepared, without the active agent. IVR devices were of cross-sectional diameter 9 mm, outer diameter 54 mm, with core cross-sectional diameter of 2 mm and core length varied as required. Sink conditions were evident for the 17b-estradiol esters in 1.0% aqueous benzalkonium chloride solution. The low release rates into 0.9% w/v saline of the lipophilic valerate and benzoate esters were due to their intrinsically low aqueous solubilities. In vivo, these esters failed to raise plasma estradiol above baseline levels in postmenopausal human volunteers, despite good in vitro release characteristics under sink conditions. The best release rates under sink conditions, in combination with substantial aqueous solubilities as indicated by the release rates into saline, were observed for the acetate and propionate esters. A
combination of drug release characteristics, short plasma half-life and a toxicologically acceptable hydrolysis product indicated that 17b-estradiol-3-acetate was the prodrug of choice for IVR delivery of ERT. In vivo, an IVR device releasing
100 mg/day of estradiol as its 3-acetate ester maintained over 84 days a circulating plasma concentration in the region of 300 pmol l , within the clinically desirable range for ERT.
Resumo:
Context. Several competing scenarios for planetary-system formation and evolution seek to explain how hot Jupiters came to be so close to their parent stars. Most planetary parameters evolve with time, making it hard to distinguish between models. The obliquity of an orbit with respect to the stellar rotation axis is thought to be more stable than other parameters such as eccentricity. Most planets, to date, appear aligned with the stellar rotation axis; the few misaligned planets so far detected are massive (> 2 MJ). Aims: Our goal is to measure the degree of alignment between planetary orbits and stellar spin axes, to search for potential correlations with eccentricity or other planetary parameters and to measure long term radial velocity variability indicating the presence of other bodies in the system. Methods: For transiting planets, the Rossiter-McLaughlin effect allows the measurement of the sky-projected angle ß between the stellar rotation axis and a planet's orbital axis. Using the HARPS spectrograph, we observed the Rossiter-McLaughlin effect for six transiting hot Jupiters found by the WASP consortium. We combine these with long term radial velocity measurements obtained with CORALIE. We used a combined analysis of photometry and radial velocities, fitting model parameters with the Markov Chain Monte Carlo method. After obtaining ß we attempt to statistically determine the distribution of the real spin-orbit angle ?. Results: We found that three of our targets have ß above 90°: WASP-2b: ß = 153°+11-15, WASP-15b: ß = 139.6°+5.2-4.3 and WASP-17b: ß = 148.5°+5.1-4.2; the other three (WASP-4b, WASP-5b and WASP-18b) have angles compatible with 0°. We find no dependence between the misaligned angle and planet mass nor with any other planetary parameter. All six orbits are close to circular, with only one firm detection of eccentricity e = 0.00848+0.00085-0.00095 in WASP-18b. No long-term radial acceleration was detected for any of the targets. Combining all previous 20 measurements of ß and our six and transforming them into a distribution of ? we find that between about 45 and 85% of hot Jupiters have ? > 30°. Conclusions: Most hot Jupiters are misaligned, with a large variety of spin-orbit angles. We find observations and predictions using the Kozai mechanism match well. If these observational facts are confirmed in the future, we may then conclude that most hot Jupiters are formed from a dynamical and tidal origin without the necessity to use type I or II migration. At present, standard disc migration cannot explain the observations without invoking at least another additional process.
Resumo:
Zearalenone (ZEN) is a mycotoxin with endocrine disrupting effects having vast economic implications in e.g. pig farming. Structurally, ZEN resembles 17b-estradiol, and thus is able to bind to estrogen receptors (ER) in target cells. Because of this, it is also classified as a non-steroidal estrogen, a phytoestrogen, a mycoestrogen, and a growth promoter. Quantitative proteomic analysis was undertaken using stable-isotope labeling by amino acids in cell culture (SILAC) upon exposure of the steroidogenesis cell model H295R with ZEN to elucidate its effect on protein regulation. ZEN significantly regulated 21 proteins, including proteins with known endocrine disrupting effects and several oncogenes. In addition, network analysis using Ingenuity Pathway Analysis showed that ZEN affected the oxidative phosphorylation pathway and the mitochondrial dysfunction pathway, both previously reported to be involved in endocrine dysfunction.
Resumo:
Constructed wetland systems (CWS) have been used as a low cost bio-filtration system to treat farm wastewater. While studies have shown that CWS are efficient in removing organic compounds and pathogens, there is limited data on the presence of hormones in this type of treatment system. The objective of this study was to evaluate the ability of the CWS to reduce estrogenic and androgenic hormone concentration in dairy wastewater. This was achieved through a year long study on dairy wastewater samples obtained froma surface flow CWS. Analysis of hormonal levels was performed using a solid phase extraction (SPE) sample clean-up method, combined with reporter gene assays (RGAs) which incorporate relevant receptors capable of measuring total estrogenic or androgenic concentrations as low as 0.24 ng L1 and 6.9 ng L1 respectively. Monthly analysis showed a mean removal efficiency for estrogens of 95.2%, corresponding to an average residual concentration of 3.2 ng L1 17b-estradiol equivalent (EEQ), below the proposed lowest observable effect concentration (LOEC) of 10 ng L1. However, for one month a peak EEQ concentration of 115 ng L1 was only reduced to 18.8 ng L1. The mean androgenic activity peaked at 360 ng L1 and a removal efficiency of 92.1% left an average residual concentration of 32.3 ng L1 testosterone equivalent (TEQ). The results obtained demonstrate that this type of CWS is an efficient system for the treatment of hormones in dairy wastewater. However, additional design improvements may be required to further enhance removal efficiency of peak hormone concentrations.
Resumo:
We present the discovery of WASP-39b, a highly inflated transiting Saturn-mass planet orbiting a late G-type dwarf star with a period of 4.055259 +/- 0.000008 d, Transit Epoch T-0 = 2 455 342.9688 +/- 0.0002 (HJD), of duration 0.1168 +/- 0.0008 d. A combined analysis of the WASP photometry, high-precision follow-up transit photometry, and radial velocities yield a planetary mass of M-pl = 0.28 +/- 0.03 M-J and a radius of R-pl = 1.27 +/- 0.04 R-J, resulting in a mean density of 0.14 +/- 0.02 rho(J). The stellar parameters are mass M-star = 0.93 +/- 0.03 M-circle dot, radius R-star = 0.895 +/- 0.23 R-circle dot, and age 9(-4)(+3) Gyr. Only WASP-17b and WASP-31b have lower densities than WASP-39b, although they are slightly more massive and highly irradiated planets. From our spectral analysis, the metallicity of WASP-39 is measured to be [Fe/H] = -0.12 +/- 0.1 dex, and we find the planet to have an equilibrium temperature of 1116(-32)(+33) K. Both values strengthen the observed empirical correlation between these parameters and the planetary radius for the known transiting Saturn-mass planets.
Resumo:
We report the discovery of the low-density, transiting giant planet WASP-31b. The planet is 0.48 Jupiter masses and 1.55 Jupiter radii. It is in a 3.4-day orbit around a metal-poor, late-F-type, V = 11.7 dwarf star, which is a member of a common proper motion pair. In terms of its low density, WASP-31b is second only to WASP-17b, which is a more highly irradiated planet of similar mass. Based in part on observations made with the HARPS spectrograph on the 3.6-m ESO telescope (proposal 085.C-0393) and with the CORALIE spectrograph and the Euler camera on the 1.2-m Euler Swiss telescope, both at the ESO La Silla Observatory, Chile.The photometric time-series and radial-velocity data used in this work are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A60
Resumo:
Zearalenone (ZEN) is a mycotoxin produced by Fusarium fungi. Once ingested, ZEN may be absorbed andmetabolised to a- and b-zearalenol (a-ZOL, b-ZOL), and to a lesser extent a- and b-zearalanol (a-ZAL,b-ZAL). Further biotransformation to glucuronide conjugates also occurs to facilitate the elimination ofthese toxins from the body. Unlike ZEN and its metabolites, information regarding the estrogenic activityof these glucuronide conjugates in various tissues is lacking. ZEN-14-O-glucuronide, a-ZOL-14-O-glucuronide,a-ZOL-7-O-glucuronide, b-ZOL-14-O-glucuronide and b-ZOL-16-O-glucuronide, previouslyobtained as the major products from preparative enzymatic synthesis, were investigated for their potentialto cause endocrine disruption through interference with estrogen receptor transcriptional activity.All five glucuronide conjugates showed a very weak agonist response in an estrogen responsive reportergene assay (RGA), with activity ranging from 0.0001% to 0.01% of that of 17b-estradiol, and also lessthan that of ZEN, a-ZOL and b-ZOL which have previously shown estrogenic potencies of the order 17bestradiol> a-ZOL > ZEN > b-ZOL. Confirmatory mass spectrometry revealed that any activity observedwas likely a result of minor deconjugation of the glucuronide moiety. This study confirms that formationof ZEN and ZOL glucuronides is a detoxification reaction with regard to estrogenicity, serving as a potentialhost defence mechanism against ZEN-induced estrogenic activity.