In this paper, we report on the design, fabrication, and characterization of a photonic circuit for biosensing applications. Silicon oxynitride with a bulk refractive index of 1.66 is the core-layer ...material. The photonic circuit is optimized for a wavelength of ∼850 nm, which allows on-chip integration of the light source via cost effective vertical-cavity surface-emitting lasers and of the detector by using standard silicon photodetectors. Design as well as fabrication processes are explained in details. The best characteristics for the single optical components in the photonic circuit are: for single-mode channel waveguides with dimensions of 350 nm × 950 nm; propagation losses of 0.8 dB/cm; bending losses of 0.1 dB/90°-bend (radius of curvature 100 μm); 49/51 splitting ratio for 3-dB power splitters (directional couplers); quality factors up to 1.3 × 10 5 for microring resonators. Volumetric sensing yields a bulk sensitivity of 80 nm/RIU and a limit of detection of 3 × 10 −6 RIU. Therefore, SiON-based photonic circuits represent a reliable material platform for biosensing in the short-wave near infrared region.
Abstract
We present the mid-infrared (5–12
μ
m) phase curve of GJ 367b observed by the Mid-Infrared Instrument on the James Webb Space Telescope (JWST). GJ 367b is a hot (
T
eq
= 1370 K), extremely ...dense (10.2 ± 1.3 g cm
−3
) sub-Earth orbiting an M dwarf on a 0.32 day orbit. We measure an eclipse depth of 79 ± 4 ppm, a nightside planet-to-star flux ratio of 4 ± 8 ppm, and a relative phase amplitude of 0.97 ± 0.10, all fully consistent with a zero-albedo planet with no heat recirculation. Such a scenario is also consistent with the phase offset of 11°E ± 5° to within 2.2
σ
. The emission spectrum is likewise consistent with a blackbody with no heat redistribution and a low albedo of
A
B
≈ 0.1, with the exception of one anomalous wavelength bin that we attribute to unexplained systematics. The emission spectrum puts few constraints on the surface composition but rules out a CO
2
atmosphere ≳1 bar, an outgassed atmosphere ≳10 mbar (under heavily reducing conditions), or an outgassed atmosphere ≳0.01 mbar (under heavily oxidizing conditions). The lack of day–night heat recirculation implies that 1 bar atmospheres are ruled out for a wide range of compositions, while 0.1 bar atmospheres are consistent with the data. Taken together with the fact that most of the dayside should be molten, our JWST observations suggest that the planet must have lost the vast majority of its initial inventory of volatiles.
In this article, we designed and studied silicon oxynitride (SiON) microring-based photonic structures for biosensing applications. We designed waveguides, directional couplers, and racetrack ...resonators in order to measure refractive index changes smaller than 10-6 refractive index units (RIU). We tested various samples with different SiON refractive indexes as well as the waveguide dimensions for selecting the sensor with the best performance. Propagation losses and bending losses have been measured on test structures, along with a complete characterization of the resonator's performances. Sensitivities and limit of detection (LOD) were also measured using glucose-water solutions and compared with expected results from simulations. Finally, we functionalized the resonator and performed sensing experiments with Aflatoxin M1 (AFM1). We were able to detect the binding of aflatoxin for concentrations as low as 12.5 nm. The results open up the path for designing cost-effective biosensors for a fast and reliable sensitive analysis of AFM1 in milk.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted)We report on the discovery and characterization of the transiting planet K2-39b (EPIC 206247743b). With an orbital period of 4.6 days, ...it is the shortest-period planet orbiting a subgiant star known to date. Such planets are rare, with only a handful of known cases. The reason for this is poorly understood but may reflect differences in planet occurrence around the relatively high-mass stars that have been surveyed, or may be the result of tidal destruction of such planets. K2-39 (EPIC 206247743) is an evolved star with a spectroscopically derived stellar radius and mass of ... and ... , respectively, and a very close-in transiting planet, with a/Rlow * = 3.4. Radial velocity (RV) follow-up using the HARPS, FIES, and PFS instruments leads to a planetary mass of ... In combination with a radius measurement of 8.3 + or - 1.1 R+ in circle, this results in a mean planetary density of ... g cm super(-3). We furthermore discover a long-term RV trend, which may be caused by a long-period planet or stellar companion. Because K2-39b has a short orbital period, its existence makes it seem unlikely that tidal destruction is wholly responsible for the differences in planet populations around subgiant and main-sequence stars. Future monitoring of the transits of this system may enable the detection of period decay and constrain the tidal dissipation rates of subgiant stars.
ABSTRACT We report the discovery of K2-31b, the first confirmed transiting hot Jupiter detected by the K2 space mission. We combined K2 photometry with FastCam lucky imaging and FIES and HARPS ...high-resolution spectroscopy to confirm the planetary nature of the transiting object and derived the system parameters. K2-31b is a 1.8-Jupiter-mass planet on a 1.26-day orbit around a G7 V star ( M , R ). The planetary radius is poorly constrained (0.7 < Rp < 1.4 RJup),15 owing to the grazing transit and the low sampling rate of the K2 photometry.16
ABSTRACT We report the discovery of K2-98b (EPIC 211391664b), a transiting Neptune-size planet monitored by the K2 mission during its Campaign 5. We combine the K2 time-series data with ground-based ...photometric and spectroscopic follow-up observations to confirm the planetary nature of the object and derive its mass, radius, and orbital parameters. K2-98b is a warm Neptune-like planet in a 10 day orbit around a V = 12.2 mag F-type star with M = 1.074 0.042 M , R = R , and age of . We derive a planetary mass and radius of Mp = 32.2 8.1 M⊕ and Rp = R⊕. K2-98b joins the relatively small group of Neptune-size planets whose mass and radius have been derived with a precision better than 25%. We estimate that the planet will be engulfed by its host star in ∼3 Gyr, due to the evolution of the latter toward the red giant branch.
TWO HOT JUPITERS FROM K2 CAMPAIGN 4 Johnson, Marshall C.; Gandolfi, Davide; Fridlund, Malcolm ...
The Astronomical journal,
06/2016, Letnik:
151, Številka:
6
Journal Article
Recenzirano
Odprti dostop
ABSTRACT We confirm the planetary nature of two transiting hot Jupiters discovered by the Kepler spacecraft's K2 extended mission in its Campaign 4, using precise radial velocity measurements from ...FIES@NOT, HARPS-N@TNG, and the coudé spectrograph on the McDonald Observatory 2.7 m telescope. K2-29 b (EPIC 211089792b) transits a K1V star with a period of 3.2589263 0.0000015 days; its orbit is slightly eccentric ( e = 0.084 − 0.023 + 0.032 ). It has a radius of R P = 1.000 − 0.067 + 0.071 RJ and a mass of M P = 0.613 − 0.026 + 0.027 MJ. Its host star exhibits significant rotational variability, and we measure a rotation period of P rot = 10.777 0.031 days. K2-30 b (EPIC 210957318 b) transits a G6V star with a period of 4.098503 0.000011 days. It has a radius of R P = 1.039 − 0.051 + 0.050 RJ and a mass of M P = 0.579 − 0.027 + 0.028 MJ. The star has a low metallicity for a hot Jupiter host, Fe / H = − 0.15 0.05 .
We report the characterization and independent detection of K2-60b, as well as the detection and characterization of K2-107b, two transiting hot gaseous planets from the K2 space mission. We confirm ...the planetary nature of the two systems and determine their fundamental parameters combining the K2 time-series data with FIES@NOT and HARPS-N@TNG spectroscopic observations. K2-60b has a radius of 0.683 0.037 RJup and a mass of 0.426 0.037 MJup and orbits a G4 V star with an orbital period of 3.00267 0.00006 days. K2-107b has a radius of 1.44 0.15 RJup and a mass of 0.84 0.08 MJup and orbits an F9 IV star every 3.31392 0.00002 days. K2-60b is among the few planets at the edge of the so-called "desert" of short-period sub-Jovian planets. K2-107b is a highly inflated Jovian planet orbiting an evolved star about to leave the main sequence.
We study the Kepler object Kepler-432, an evolved star ascending the red giant branch. By deriving precise radial velocities from multi-epoch high-resolution spectra of Kepler-432 taken with the CAFE ...spectrograph at the 2.2 m telescope of Calar Alto Observatory and the FIES spectrograph at the Nordic Optical Telescope of Roque de Los Muchachos Observatory, we confirm the planetary nature of the object Kepler-432 b, which has a transit period of 52 days. We find a planetary mass of Mp = 5.84 ± 0.05MJup and a high eccentricity of e = 0.478 ± 0.004. With a semi-major axis of a = 0.303 ± 0.007 AU, Kepler-432 b is the first bona fide warm Jupiter detected to transit a giant star. We also find a radial velocity linear trend of γ̇ = 0.44 ± 0.04 m s-1 d-1, which suggests the presence of a third object in the system. Current models of planetary evolution in the post-main-sequence phase predict that Kepler-432 b will be most likely engulfed by its host star before the latter reaches the tip of the red giant branch.
In this work, we present a study of the Sensitivity (S) and Limit of Detection (LOD) of microring based photonic biosensors as a function of the waveguide composition and dimensions. The target is ...Aflatoxin, which is a toxin of major concern for south Europe dairy industry. The sensing device is based on an array of multiple SiON microring resonators, fiber-coupled to both an 850 nm VCSEL and a silicon photodetectors, packaged with a microfluidic circuit. Volumetric sensing with glucose–water solutions of various concentrations yields a best sensitivity of 112 nm/RIU. To link these results to the Limit of Detection of the sensors, we also measured the noise of our experimental readout system and then calculated the LOD of our sensors. We found a best value of LOD of 1.6 × 10−6 RIU (referred to volumetric sensing). Finally, we detected Aflatoxin in solutions of various concentrations (down to 1.58 nM) by functionalized sensors. The functionalization is based on a wet silanization and specific DNA-aptamer binding on the chip. Reproducibility and re-usability of the sensor are investigated by several chemical treatments. Optimum procedure allows multiple sequential measurements with a good endurance. This work was supported by the FP7 EU project “Symphony” (Grant agreement no.: 610580). Keywords: Biosensor, Whispering Gallery Mode, Ring resonator, Aflatoxin, Limit of Detection, Sensitivity
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