scholarly journals Infrared spectroscopy of exoplanets: observational constraints

Author(s):  
Thérèse Encrenaz

The exploration of transiting extrasolar planets is an exploding research area in astronomy. With more than 400 transiting exoplanets identified so far, these discoveries have made possible the development of a new research field, the spectroscopic characterization of exoplanets' atmospheres, using both primary and secondary transits. However, these observations have been so far limited to a small number of targets. In this paper, we first review the advantages and limitations of both primary and secondary transit methods. Then, we analyse what kind of infrared spectra can be expected for different types of planets and discuss how to optimize the spectral range and the resolving power of the observations. Finally, we propose a list of favourable targets for present and future ground-based observations.

Author(s):  
Bin Guo ◽  
Yunji Liang ◽  
Zhu Wang ◽  
Zhiwen Yu ◽  
Daqing Zhang ◽  
...  

In the past decades, numerous research efforts have been made to model and extract the contexts of users in pervasive computing environments. The recent explosion of sensor-equipped mobile phone market and the phenomenal growth of geo-tagged data (Twitter messages, Foursquare check-ins, etc.) have enabled the analysis of new dimensions of contexts that involve the social and urban context. The technology trend towards pervasive sensing and large-scale social and community computing is making “Social and Community Intelligence (SCI)” a new research area that aims at investigating individual/group behavior patterns, community and urban dynamics based on the “digital footprints.” It is believed that the SCI technology has the potential to revolutionize the field of context-aware computing. The aim of this chapter is to identify this emerging research area, present the research background, define the general system framework, characterize its unique properties, discuss the open research challenges, and present this emerging research field.


2020 ◽  
Author(s):  
Florian Debras ◽  
Gilles Chabrier

<p><span lang="en-US">Juno's observations of Jupiter's gravity field have revealed extremely low values for the gravitational moments that are difficult to reconcile with the high abundance of metals observed in the atmosphere by Galileo. Recent studies chose to arbitrarily get rid of one of these two constraints in order to build models of Jupiter.</span></p> <p><span lang="en-US">In this presentation, I will detail our new Jupiter structure models reconciling Juno and Galileo observational constraints. These models confirm the need to separate Jupiter into at least 4 layers: an outer convective shell, a non-convective zone of compositional change, an inner convective shell and a diluted core representing about 60 percent of the planet in radius. Compared to other studies, these models propose a new idea with important consequences: a decrease in the quantity of metals between the outer and inner convective shells. This would imply that the atmospheric composition is not representative of the internal composition of the planet, contrary to what is regularly admitted, and would strongly impact the Jupiter formation scenarios (localization, migration, accretion).</span></p> <p><span lang="en-US">In particular, the presence of an internal non-convective zone prevents mixing between the two convective envelopes. I will detail the physical processes of this semi-convective zone (layered convection or H-He immiscibility) and explain how they may persist during the evolution of the planet.</span></p> <p><span lang="en-US">These models also impose a limit mass on the compact core, which cannot be heavier than 5 Earth masses. Such a mass, lower than the runaway gas accretion minimum mass, needs to be explained in the light of our understanding of the formation and evolution of giant planets.</span></p> <p><span lang="en-US">Using these models of Jupiter, I will finally detail the application of our new understanding of the interior of this planet to giant exoplanets. At a time of direct imaging of extrasolar planets and atmospheric characterization of hot Jupiters, a good understanding of the internal processes of planets in the solar system is paramount to make the best use of all the observations.</span></p>


2017 ◽  
Vol 41 (14) ◽  
pp. 6742-6759 ◽  
Author(s):  
A. Borba ◽  
J. P. Vareda ◽  
L. Durães ◽  
A. Portugal ◽  
P. N. Simões

The structural and spectroscopic properties of silica aerogels were studied using complementary approaches, such as Fourier transform infrared spectroscopy and solid-state NMR spectroscopy.


2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Kyle Gipson ◽  
Kathryn Stevens ◽  
Phil Brown ◽  
John Ballato

Organicallycoated inorganic nanoparticles were synthesized to produce photoluminescent nanocomposites based on a polymethyl methacrylate (PMMA) matrix. The nanoparticles comprised organic ligands (acetylsalicylic acid, ASA, and 2-picolinic acid, PA) attached to the lanthanum trifluoride (LaF3) host crystals that were doped with optically active terbium III (Tb3+) and synthesized using solution-based methods. The ligands were employed to functionalize the surface of Tb3+:LaF3nanocrystals to aid in dispersing the nanoparticles. In order to confirm the presence of the constituents within the inorganic-organic system, the nanoparticles were characterized by infrared spectroscopy and energy-dispersive X-ray spectroscopy. Absorption peaks observed from infrared spectroscopy for all the polymer nanocomposites loaded with organic surface treated nanocrystals exhibited peaks that were not present in undoped PMMA but were characteristic of the dopant and the ligand.


Author(s):  
Per Andersson ◽  
Susanne Sweet ◽  
Christopher Rosenqvist

This chapter puts focus on and relates to three central concepts “sustainability”, “mobility”, and “customer value”. The results from two long-term lines of research and two research programs are combined in the chapter. The first focuses on the effects of the use of new wireless communication and information on organizations in terms of changed “mobility” of people and artifacts within and between organizations. The second research area addressed is that of social and environmental enterprise and business. The chapter has the aim and ambition to contribute to a conceptual discussion on sustainability, mobility, and value. Based on the discussion, the chapter presents a set of propositions to help advance research in this relatively new research field. Short empirical examples are presented, followed by a concluding discussion and a set of propositions for further research.


2012 ◽  
pp. 1909-1926
Author(s):  
Per Andersson ◽  
Susanne Sweet ◽  
Christopher Rosenqvist

This chapter puts focus on and relates to three central concepts “sustainability”, “mobility”, and “customer value”. The results from two long-term lines of research and two research programs are combined in the chapter. The first focuses on the effects of the use of new wireless communication and information on organizations in terms of changed “mobility” of people and artifacts within and between organizations. The second research area addressed is that of social and environmental enterprise and business. The chapter has the aim and ambition to contribute to a conceptual discussion on sustainability, mobility, and value. Based on the discussion, the chapter presents a set of propositions to help advance research in this relatively new research field. Short empirical examples are presented, followed by a concluding discussion and a set of propositions for further research.


Clay Minerals ◽  
1996 ◽  
Vol 31 (2) ◽  
pp. 233-241 ◽  
Author(s):  
J. Madejová ◽  
J. Bujdák ◽  
W. P. Gates ◽  
P. Komadel

AbstractA series of reduced-charge montmorillonites (RCMs) was prepared from Li-montmorillonite from Jelšový Potok (Slovakia) by heating at various temperatures (105–210°C for 24 h. The amount of fixed Li, 0.09–0.67 per O20(OH)4, increased with increasing temperature, confirming preparation of a set of samples of variable layer charge from the same parent Li-montmorillonite by varying only the preparation temperature. Infrared spectroscopy revealed that Li was trapped in the hexagonal cavities of the tetrahedral sheet at all temperatures. Partial deprotonation of the samples, reflected in the decrease of the intensities of the OH-bending bands, was observed after treatments above 120°C. Analysis of the OH-stretching region showed Li in the previously vacant octahedra in the samples heated above 150°C. Weak inflections near 660 and 720 cm−1 confirmed development of local trioctahedral character of octahedral cations coordinated with OH groups in the sample heated at 210°C. Gradual decrease of the layer charge due to Li fixation led to a shift of the Si-O stretching band to higher frequencies and to the appearance of new, pyrophyllite-like bands at 1120 and 419 cm−1.


Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 92
Author(s):  
Alina Năstaca Coman ◽  
Anca Mare ◽  
Corneliu Tanase ◽  
Eugen Bud ◽  
Aura Rusu

The main disadvantage of the implants is the associated infections. Therefore, in the long term, the possibility of improving the antibacterial capacity of different types of implants (dental, orthopedic) is being researched. The severity of the problem lies in the increasing bacterial resistance and finding appropriate alternative treatments for infectious diseases, which is an important research field nowadays. The purpose of this review is to draw a parallel between different studies analyzing the antibacterial activity and mechanism of silver nanoparticles (NP Ag) deposited on the titanium nanotubes (NTT), as well as the analysis of the NP Ag toxicity. This review also provides an overview of the synthesis and characterization of TiO2-derived nanotubes (NT). Thus, the analysis aims to present the existing knowledge to better understand the NP Ag implants benefits and their antibacterial activity.


Sign in / Sign up

Export Citation Format

Share Document