Search results for "620 Engineering"
showing 10 items of 12 documents
A giant exoplanet orbiting a very-low-mass star challenges planet formation models
2019
Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts con…
Design, characterization, and first field deployment of a novel aircraft-based aerosol mass spectrometer combining the laser ablation and flash vapor…
2021
In this paper, we present the design, development, and characteristics of the novel aerosol mass spectrometer ERICA (ERC Instrument for Chemical composition of Aerosols; ERC – European Research Council) and selected results from the first airborne field deployment. The instrument combines two well-established methods of real-time in situ measurements of fine particle chemical composition. The first method is the laser desorption and ionization technique, or laser ablation technique, for single-particle mass spectrometry (here with a frequency-quadrupled Nd:YAG laser at λ = 266 nm). The second method is a combination of thermal particle desorption, also called flash vaporization, and electro…
Sublimation of icy aggregates in the coma of comet 67P/Churyumov–Gerasimenko detected with the OSIRIS cameras on board Rosetta
2016
Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov¿Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analysed the dust monitoring observations shortly after the southern vernal equinox on 2015 May 30 and 31 with the WAC at the heliocentric distance Rh = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness a…
Reliability of genomic variants across different next-generation sequencing platforms and bioinformatic processing pipelines
2021
Abstract Background Next Generation Sequencing (NGS) is the fundament of various studies, providing insights into questions from biology and medicine. Nevertheless, integrating data from different experimental backgrounds can introduce strong biases. In order to methodically investigate the magnitude of systematic errors in single nucleotide variant calls, we performed a cross-sectional observational study on a genomic cohort of 99 subjects each sequenced via (i) Illumina HiSeq X, (ii) Illumina HiSeq, and (iii) Complete Genomics and processed with the respective bioinformatic pipeline. We also repeated variant calling for the Illumina cohorts with GATK, which allowed us to investigate the e…
The realization of autonomous, aircraft-based, real-time aerosol mass spectrometry in the upper troposphere and lower stratosphere
2022
Abstract. We report on the developments that enabled the field deployment of a fully-automated aerosol mass spectrometer, specially designed for high-altitude measurements on unpressurised aircraft. The merits of the two main categories of real-time aerosol mass spectrometry, i.e. (a) single particle laser desorption and ionization, and (b) continuous thermal desorption / electron impact ionization of aerosols, have been integrated into one compact apparatus with the aim to perform in-situ real-time analysis of aerosol chemical composition. The demonstrated instrument, named ERICA (European Research council Instrument for the Chemical composition of Aerosols), operated successfully aboard t…
Toward Three-Dimensional Chemical Imaging of Ternary Cu–Sn–Pb Alloys Using Femtosecond Laser Ablation/Ionization Mass Spectrometry
2017
Femtosecond laser ablation/ionization mass spectrometry (LIMS) has been applied to probe the spatial element composition of three ternary Cu-Sn-Pb model bronze alloys (lead bronzes: CuSn10Pb10, CuSn7Pb15, and CuSn5Pb20), which were recently identified as high-performance cathode materials in the context of electro-organic synthesis (dehalogenation, deoxygenation) of pharmaceutically relevant building blocks. The quantitative and spatially resolved element analysis of such cathode materials will help in understanding the observed profound differences in their electrochemical reactivity and stability. For that purpose, we developed a measurement procedure using the LIMS technique which allows…
Ultrafast spectroscopic investigation on fluorescent carbon nanodots: the role of passivation.
2019
Disentangling the respective roles of the surface and core structures in the photocycle of carbon nanodots is a critical open problem in carbon nanoscience. While the need of passivating carbon dot surfaces to obtain efficiently emitting nanoparticles is very well-known in the literature, it is unclear if passivation introduces entirely new surface emitting states, or if it stabilizes existing states making them fluorescent. In this multi-technique femtosecond spectroscopy study, the relaxation dynamics of non-luminescent (non-passivated) carbon dots are directly compared with their luminescent (passivated) counterparts. Non-passivated dots are found to host emissive states, albeit very sho…
The interaction of photoexcited carbon nanodots with metal ions disclosed down to the femtosecond scale
2017
Fluorescent carbon nanodots are a novel family of carbon-based nanoscale materials endowed with an outstanding combination of properties that make them very appealing for applications in nanosensing, photonics, solar energy harvesting and photocatalysis. One of the remarkable properties of carbon dots is their strong sensitivity to the local environment, especially to metal ions in solution. These interactions provide a testing ground for their marked photochemical properties, highlighted by many studies, and frequently driven by charge transfer events. Here we combine several optical techniques, down to femtosecond time resolution, to understand the interplay between carbon nanodots and aq…
Dual Luminescence, Interligand Decay, and Nonradiative Electronic Relaxation of Cyclometalated Iridium Complexes in Solution
2016
Femtosecond broadband photoluminescence studies are presented for Ir(ppy)3 (Ir1), Ir(ppy)2(pic) (Ir2), Ir(ppy)2(bpy)(PF6) (Ir3), Ir(ppz)3 (Ir4), and Ir(ppz)2dipy (Ir5) (where ppy = 2-phenylpyridine, pic = picolinate, bpy = 2,2′-bipyridine, ppz = 1-phenylpyrazole, and dipy = 5-phenyldipyrrinato) in solution. Upon 400-nm excitation of Ir1–Ir3, we observed a prompt population of the lowest MLCT states. The higher states decay on an ultrafast time scale (3MLCT state undergoes further vibrational relaxation on a 1-ps time scale. In Ir3, this relaxation is accompanied by an interligand decay from the ppy to the bpy ligand in ∼1.5 ps. For the ppy-containing complexes (Ir1 and Ir2), we found that, …
Disentangling size effects and spectral inhomogeneity in carbon nanodots by ultrafast dynamical hole-burning.
2018
Carbon nanodots (CDs) are a novel family of nanomaterials exhibiting unique optical properties. In particular, their bright and tunable fluorescence redefines the paradigm of carbon as a "black" material and is considered very appealing for many applications. While the field keeps growing, understanding CDs fundamental properties and relating them to their variable structures becomes more and more critical. Two crucial problems concern the effect of size on the electronic structure of CDs, and to what extent their optical properties are influenced by structural disorder. Furthermore, it remains largely unclear whether traditional concepts borrowed from the photo-physics of semiconductor qua…