Artigos de revistas: "Various atmospheres"

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Kotobuki, Masashi, Binngong Yan, Li Lu, Emil Hanc e Joanna Molenda. "Study on stabilization of cubic Li7La3Zr2O12 by Ge substitution in various atmospheres". Functional Materials Letters 09, n.º 06 (dezembro de 2016): 1642005. http://dx.doi.org/10.1142/s1793604716420054.

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Stabilization of high Li ion conductive cubic Li7La3Zr2O[Formula: see text] (LLZ) by Ge substitution in air, N2/O2 and N2 atmospheres are studied by high temperature XRD (HT-XRD) of Ge-added tetragonal LLZ (Ge-LLZ). A formation of low temperature cubic phase caused by CO2 absorption during storage of the Ge-LLZ is observed at about 160[Formula: see text]C in all atmospheres. Additionally, impurity formation of La2Zr2O7 and La2O3 also occurs in all atmospheres. On the other hand, stabilization of cubic phase by substitution of Ge is largely influenced by the atmosphere. The cubic phase is observed at 40[Formula: see text]C after heating Ge-LLZ to 700[Formula: see text]C in air while only tetragonal phase appeared after heating in N2/O2. It is concluded that the heating atmosphere largely influences substitution of Ge, resulting in stabilization of the high Li ion conductive cubic phase.

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Hainich, R., V. Ramachandran, T. Shenar, A. A. C. Sander, H. Todt, D. Gruner, L. M. Oskinova e W. R. Hamann. "PoWR grids of non-LTE model atmospheres for OB-type stars of various metallicities". Astronomy & Astrophysics 621 (janeiro de 2019): A85. http://dx.doi.org/10.1051/0004-6361/201833787.

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The study of massive stars in different metallicity environments is a central topic of current stellar research. The spectral analysis of massive stars requires adequate model atmospheres. The computation of such models is difficult and time-consuming. Therefore, spectral analyses are greatly facilitated if they can refer to existing grids of models. Here we provide grids of model atmospheres for OB-type stars at metallicities corresponding to the Small and Large Magellanic Clouds, as well as to solar metallicity. In total, the grids comprise 785 individual models. The models were calculated using the state-of-the-art Potsdam Wolf-Rayet (PoWR) model atmosphere code. The parameter domain of the grids was set up using stellar evolution tracks. For all these models, we provide normalized and flux-calibrated spectra, spectral energy distributions, feedback parameters such as ionizing photons, Zanstra temperatures, and photometric magnitudes. The atmospheric structures (the density and temperature stratification) are available as well. All these data are publicly accessible through the PoWR website.

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Miller-Ricci, Eliza, Sara Seager e Dimitar Sasselov. "The Atmospheres of Extrasolar Super-Earths". Proceedings of the International Astronomical Union 4, S253 (maio de 2008): 263–71. http://dx.doi.org/10.1017/s1743921308026483.

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AbstractExtrasolar super-Earths (1-10 M⊕) are likely to exist with a wide range of atmospheres. While a number of these planets have already been discovered through radial velocities and microlensing, it will be the discovery of the firsttransitingsuper-Earths that will open the door to a variety of follow-up observations aimed at characterizing their atmospheres. Super-Earths may fill a large range of parameter space in terms of their atmospheric composition and mass. Specifically, some of these planets may have high enough surface gravities to be able to retain large hydrogen-rich atmosphseres, while others will have lost most of their hydrogen to space over the planet's lifetime, leaving behind an atmosphere more closely resembling that of Earth or Venus. The resulting composition of the super-Earth atmosphere will therefore depend strongly on factors such as atmospheric escape history, outgassing history, and the level of stellar irradiation that it receives. Here we present theoretical models of super-Earth emission and transmission spectra for a variety of possible outcomes of super-Earth atmospheric composition ranging from hydrogen-rich to hydrogen-poor. We focus on how observations can be used to differentiate between the various scenarios and constrain atmospheric composition.

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Adhami, Touraj, Reza Ebrahimi-Kahrizsangi, Hamid Reza Bakhsheshi-Rad, Somayeh Majidi, Milad Ghorbanzadeh e Filippo Berto. "Synthesis and Electrochemical Properties of TiNb2O7 and Ti2Nb10O29 Anodes under Various Annealing Atmospheres". Metals 11, n.º 6 (20 de junho de 2021): 983. http://dx.doi.org/10.3390/met11060983.

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In this study, two compounds of TiNb2O7 and Ti2Nb10O29 were successfully synthesized by mechanochemical method and post-annealing as an anode material for lithium-ion batteries. The effect of annealing atmosphere on the morphology, particle size, and electrochemical characteristics of two compounds was investigated. For these purposes, the reactive materials were milled under an argon atmosphere with a certain mole ratio. Subsequently, each sample was subjected to annealing treatment in two different atmospheres, namely argon and oxygen. Phase and morphology identifications were carried out by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) to identify the phases and evaluate the morphology of the synthesized samples. The charging and discharging tests were conducted using a battery-analyzing device to evaluate the electrochemical properties of the fabricated anodes. Annealing in different atmospheres resulted in variable discharge capacities so that the two compounds of TiNb2O7 and Ti2Nb10O29 annealed under the argon atmosphere showed a capacity of 60 and 66 mAh/g after 179 cycles, respectively, which had a lower capacity than their counterpart under the oxygen atmosphere. The final capacity of the annealed samples in the oxygen atmosphere is 72 and 74 mAh/g, respectively.

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Park, Sang Yeup, e Hee Gon Bang. "Effect of Sintering Atmospheres on the Microstructure Evolution of Alumina/Alumina:SiC Whisker Laminate Composites". Materials Science Forum 486-487 (junho de 2005): 237–40. http://dx.doi.org/10.4028/www.scientific.net/msf.486-487.237.

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Alumina/Alumina: SiC laminate composites were fabricated by the pressureless sintering method. Although the laminate defect, such as channel crack, was observed under the sintering of oxidation atmosphere, laminate defects were eliminated by the sintering of non-oxidation atmospheres. Among various atmospheres, the vacuum atmosphere was effective in the elimination of laminate defects and also for homogeneous microstructure.

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Abbas, Ahmed A., Naser Al Falahy e Abdullah Kh Ahmed. "The Effect of Tropospheric Scintillation on Microwave Frequencies for GSM System in The Iraqi Atmosphere". International Journal of Electrical and Electronics Research 10, n.º 3 (30 de setembro de 2022): 747–50. http://dx.doi.org/10.37391/ijeer.100355.

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Several papers have been published recently on the effects of scintillation on microwave propagation in standard atmospheres. Most of them have analyzed theoretically the influence of various parameters on the propagation, but barely a few researchers were able to extract the results from the model relying on microwave links in a nonstandard atmosphere. A method is proposed to predict the tropospheric scintillation on the space path of Earth for both standard and nonstandard atmospheres using the frequency range (20-38) GHz which is used in the Global System for Mobile (GSM). This method can be applied to the different atmospheric conditions in different regions. This work studied the effects of various parameters, such as antenna diameter, meteorological elements t (average temperature), H (relative humidity), and water vapor pressure and frequency, on the scintillation magnitude of GSM bands in Basrah and Baghdad.

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Kaźmierczak-Bałata, Anna, Jerzy Bodzenta, Piotr Szperlich, Marcin Jesionek, Anna Michalewicz, Alina Domanowska, Jeyanthinath Mayandi, Vishnukanthan Venkatachalapathy e Andrej Kuznetsov. "Impact of Annealing in Various Atmospheres on Characteristics of Tin-Doped Indium Oxide Layers towards Thermoelectric Applications". Materials 17, n.º 18 (20 de setembro de 2024): 4606. http://dx.doi.org/10.3390/ma17184606.

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The aim of this work was to investigate the possibility of modifying the physical properties of indium tin oxide (ITO) layers by annealing them in different atmospheres and temperatures. Samples were annealed in vacuum, air, oxygen, nitrogen, carbon dioxide and a mixture of nitrogen with hydrogen (NHM) at temperatures from 200 °C to 400 °C. Annealing impact on the crystal structure, optical, electrical, thermal and thermoelectric properties was examined. It has been found from XRD measurements that for samples annealed in air, nitrogen and NHM at 400 °C, the In2O3/In4Sn3O12 share ratio decreased, resulting in a significant increase of the In4Sn3O12 phase. The annealing at the highest temperature in air and nitrogen resulted in larger grains and the mean grain size increase, while vacuum, NHM and carbon dioxide atmospheres caused the decrease in the mean grain size. The post-processing in vacuum and oxidizing atmospheres effected in a drop in optical bandgap and poor electrical properties. The carbon dioxide seems to be an optimal atmosphere to obtain good TE generator parameters—high ZT. The general conclusion is that annealing in different atmospheres allows for controlled changes in the structure and physical properties of ITO layers.

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Madhusudhan, Nikku. "Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects". Annual Review of Astronomy and Astrophysics 57, n.º 1 (18 de agosto de 2019): 617–63. http://dx.doi.org/10.1146/annurev-astro-081817-051846.

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Exoplanetary science is on the verge of an unprecedented revolution. The thousands of exoplanets discovered over the past decade have most recently been supplemented by discoveries of potentially habitable planets around nearby low-mass stars. Currently, the field is rapidly progressing toward detailed spectroscopic observations to characterize the atmospheres of these planets. Various surveys from space and the ground are expected to detect numerous more exoplanets orbiting nearby stars that make the planets conducive for atmospheric characterization. The current state of this frontier of exoplanetary atmospheres may be summarized as follows. ▪ We have entered the era of comparative exoplanetology thanks to high-fidelity atmospheric observations now available for tens of exoplanets. ▪ Recent studies reveal a rich diversity of chemical compositions and atmospheric processes hitherto unseen in the Solar System. ▪ Elemental abundances of exoplanetary atmospheres place important constraints on exoplanetary formation and migration histories. ▪ Upcoming observational facilities promise to revolutionize exoplanetary spectroscopy down to rocky exoplanets. ▪ The detection of a biosignature in an exoplanetary atmosphere is conceivable over the next decade. In the present review, we discuss the modern and future landscape of this frontier area of exoplanetary atmospheres. We start with a brief review of the area, emphasising the key insights gained from different observationalmethods and theoretical studies. This is followed by an in-depth discussion of the state of the art, challenges, and future prospects in three forefront branches of the area.

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Kuzucan, Asena, Emeline Bolmont, Guillaume Chaverot, Jaqueline Quirino Ferreira, Bastiaan Willem Ibelings, Siddharth Bhatnagar e Daniel Frank McGinnis. "The Role of Atmospheric Composition in Defining the Habitable Zone Limits and Supporting E. coli Growth". Life 15, n.º 1 (10 de janeiro de 2025): 79. https://doi.org/10.3390/life15010079.

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Studying exoplanet atmospheres is essential for assessing their potential to host liquid water and their capacity to support life (their habitability). Each atmosphere uniquely influences the likelihood of surface liquid water, defining the habitable zone (HZ)—the region around a star where liquid water can exist. However, being within the HZ does not guarantee habitability, as life requires more than just liquid water. In this study, we adopted a two-pronged approach. First, we estimated the surface conditions of planets near the HZ’s inner edge under various atmospheric compositions. By utilizing a 3D climate model, we refined the inner boundaries of the HZ for planets with atmospheres dominated by H2 and CO2 for the first time. Second, we investigated microbial survival in these environments, conducting laboratory experiments on the growth and survival of E. coli K-12, focusing on the impact of different gas compositions. This innovative combination of climate modeling and biological experiments bridges theoretical climate predictions with biological outcomes. Our findings indicate that atmospheric composition significantly affects bacterial growth patterns, highlighting the importance of considering diverse atmospheres in evaluating exoplanet habitability and advancing the search for life beyond Earth.

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Turner, Jennifer, Dominique Moran e Yvonne Jewkes. "‘It's in the air here’: Atmosphere(s) of incarceration". Incarceration 3, n.º 3 (3 de agosto de 2022): 263266632211107. http://dx.doi.org/10.1177/26326663221110788.

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Contrary to descriptions of a desensitising situation – with restrictions on movement, monotonous regimes and sparse surroundings – much research highlights imprisonment as sensorially and emotionally powerful. Following work within the ‘turn to affect’ that focuses on non-verbal, non-conscious and, often, non-human embodied experiences, scholars have attended to how such elements cohere into ‘atmospheres’. Whilst the language of atmosphere is synonymous with the prison – a space that is widely anecdotally considered to conjure a particular ‘feeling’ – discussion of the mechanisms for and experiences of atmospheric production and consumption in this space has, thus far, evaded scholarly attention. Atmosphere is a word often used in prison literature, but it is rarely analytically unpacked. Accordingly, drawing on qualitative research data from individuals designing, and working and living in prisons, we focus on how various components – including aesthetics, olfaction, temperature, and the performances that arise from them – comprise sensory atmospheric affects in prison. In doing so, we find atmosphere(s) emerge – not simply from the materiality of the prison itself, but from cultural constructions of carceral and non-carceral landscapes and in conjunction with personal practice and preference. Accordingly, the prison is tied to particular constructions about what a prison should feel like and how people should (re)act to/in such spaces. In some cases, prison designers attempt to engineer particular atmospheres that cohere with wider political motivations around penal philosophies. However, despite the common reflection that prisons generate some kind of atmosphere, respondents are unable to offer a concrete description of what this may be, and much of our data highlights a definite precarity and changeability to atmospheric affect, which is likely to raise ambiguity around attempts to design carceral atmospheres.

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Rimmer, P. B., Ch Helling e C. Bilger. "The influence of galactic cosmic rays on ion–neutral hydrocarbon chemistry in the upper atmospheres of free-floating exoplanets". International Journal of Astrobiology 13, n.º 2 (abril de 2014): 173–81. http://dx.doi.org/10.1017/s1473550413000487.

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AbstractCosmic rays may be linked to the formation of volatiles necessary for prebiotic chemistry. We explore the effect of cosmic rays in a hydrogen-dominated atmosphere, as a proof-of-concept that ion–neutral chemistry may be important for modelling hydrogen-dominated atmospheres. In order to accomplish this, we utilize Monte Carlo cosmic ray transport models with particle energies of 106 eV<E<1012 eV in order to investigate the cosmic-ray enhancement of free electrons in substellar atmospheres. Ion–neutral chemistry is then applied to a Drift–Phoenix model of a free-floating giant gas planet. Our results suggest that the activation of ion–neutral chemistry in the upper atmosphere significantly enhances formation rates for various species, and we find that C2H2, C2H4, NH3, C6H6 and possibly C10H are enhanced in the upper atmospheres because of cosmic rays. Our results suggest a potential connection between cosmic-ray chemistry and the hazes observed in the upper atmospheres of various extrasolar planets. Chemi-ionization reactions are briefly discussed, as they may enhance the degree of ionization in the cloud layer.

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GRIGORIADIS, SPYROS G., PAVLOS A. KOIDIS, KYRIAKOS P. VARELTZIS e CHRISTOS A. BATZIOS. "Survival of Campylobacter jejuni Inoculated in Fresh and Frozen Beef Hamburgers stored under Various Temperatures and Atmospheres". Journal of Food Protection 60, n.º 8 (1 de agosto de 1997): 903–7. http://dx.doi.org/10.4315/0362-028x-60.8.903.

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The viability of Campylobacter jejuni strains FRI-CF 401S and FRI-CF 25 inoculated in fresh and frozen beef hamburgers was investigated. Hamburgers were stored in the following conditions: 100% air at 4°C for 15 days, 100% CO2, and 100% N2 atmospheres at 4°C for 60 days and −18°C for 90 days. The data showed that 100% air was the most toxic atmosphere to C. jejuni strains. The C. jejuni populations decreased significantly faster (P ≤ 0.05) in the inoculated hamburgers in modified atmospheres than in those at −18°C. Fresh or frozen beef hamburgers contaminated by C. jejuni could always be a principal source of human campylobacteriosis.

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Katyal, Nisha, Gianluigi Ortenzi, John Lee Grenfell, Lena Noack, Frank Sohl, Mareike Godolt, Antonio García Muñoz, Franz Schreier, Fabian Wunderlich e Heike Rauer. "Effect of mantle oxidation state and escape upon the evolution of Earth’s magma ocean atmosphere". Astronomy & Astrophysics 643 (novembro de 2020): A81. http://dx.doi.org/10.1051/0004-6361/202038779.

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Context. The magma ocean period was a critical phase determining how Earth’s atmosphere developed into habitability. However, there are major uncertainties in the role of key processes such as outgassing from the planetary interior and escape of species to space that play a major role in determining the atmosphere of early Earth. Aims. We investigate the effect of outgassing of various species and escape of H2 for different mantle redox states upon the composition and evolution of the atmosphere for the magma ocean period. Methods. We included an important new atmosphere-interior coupling mechanism: the redox evolution of the mantle, which strongly affects the outgassing of species. We simulated the volatile outgassing and chemical speciation at the surface for various redox states of the mantle by employing a C-H-O based chemical speciation model combined with an interior outgassing model. We then applied a line-by-line radiative transfer model to study the remote appearance of the planet in terms of the infrared emission and transmission. Finally, we used a parameterized diffusion-limited and XUV energy-driven atmospheric escape model to calculate the loss of H2 to space. Results. We have simulated the thermal emission and transmission spectra for reduced and oxidized atmospheres present during the magma ocean period of Earth. Reduced/thin atmospheres consisting of H2 in abundance emit more radiation to space and have a larger effective height than oxidized/thick atmospheres, which are abundant in H2O and CO2. We obtain that the outgassing rates of H2 from the mantle into the atmosphere are a factor of ten times higher than the rates of diffusion-limited escape to space. We estimate the timescale of total mass loss of outgassed H2 via escape to be few tens of million years, which is comparable to other studies. Conclusions. Our work presents useful insight into the development of the terrestrial atmosphere during the magma ocean period and provides input to guide future studies that discuss exoplanetary interior compositions and their possible links with atmospheric compositions that might be estimated from observed infrared spectra by future missions.

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Ohno, Kazumasa. "Photochemical Hazes in Exoplanetary Skies with Diamonds: Microphysical Modeling of Haze Composition Evolution via Chemical Vapor Deposition". Astrophysical Journal 977, n.º 2 (1 de dezembro de 2024): 188. https://doi.org/10.3847/1538-4357/ad8e67.

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Abstract Observational efforts in the last decade suggest the prevalence of photochemical hazes in exoplanetary atmospheres. Recent JWST observations raise growing evidence that exoplanetary hazes tend to have reflective compositions, unlike the conventionally assumed haze analogs, such as tholin and soot. In this study, I propose a novel hypothesis: diamond formation through chemical vapor deposition (CVD) may be happening in exoplanetary atmospheres. Using an aerosol microphysical model combined with the theory of CVD diamond and soot formation established in the industry community, I study how the haze composition evolves in exoplanetary atmospheres for various planetary equilibrium temperatures, atmospheric metallicity, and C/O ratio. I find that CVD diamond growth dominates over soot growth in a wide range of planetary parameters. Diamond haze formation is most efficient at T eq ∼ 1000 K and low atmospheric metallicity ([M/H] ≤ 2.0), while soot could be the main haze component only if the atmosphere is hot (T eq ≳ 1200 K) and carbon rich (C/O > 1). I also compute transmission, emission, and reflected light spectra, thereby suggesting possible observational signatures of diamond hazes, including the 3.53 μm feature of hydrogenated diamonds, anomalously faint thermal emission due to thermal scattering, and a drastic increase in geometric albedo. This study suggests that warm exoplanetary atmospheres may be favorable sites for forming CVD diamonds, which would be testable by future observations by JWST and Ariel as well as haze synthesis experiments under hot hydrogen-rich conditions.

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Carpenter, Alan, Sandy Wright e Phillip Lash. "Response of adult New Zealand flower thrips,Thrips obscuratus(Thysanoptera: Thripidae) to high carbon dioxide and low oxygen atmospheres at various temperatures". Bulletin of Entomological Research 86, n.º 3 (junho de 1996): 217–21. http://dx.doi.org/10.1017/s0007485300052494.

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AbstractMortality responses of adult New Zealand flower thrips,Thrips obscuratus(Crawford) to controlled atmospheres were assessed. Temperature (0–48°C) and time (1–24 h) had major effects on mortality. There were approximately two-fold increases in thrips mortality between atmospheres with 40 and 60% CO2, when there was 0 or 2% O2present in treatments of 0°C for 4 h and 24 h; 12°C for all exposure times; 24°C for 1 h. Thrips mortality was significantly greater when there was no O2in the test atmosphere, than when there was 0.25, 8 or 12 or 20% O2. The results show that there are a variety of ways produce infested with New Zealand flower thrips could be treated with controlled atmospheres to achieve high mortality. These data can be used as the basis of potential quarantine treatments depending on the produce being exported.

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Ikegami, Takayasu, e Katsuya Eguchi. "Two kinds of roles of MgO in the densification and grain growth of alumina under various atmospheres: Sensitive and insensitive roles to the experimental procedures". Journal of Materials Research 14, n.º 2 (fevereiro de 1999): 509–17. http://dx.doi.org/10.1557/jmr.1999.0073.

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Two kinds of high-purity Al2O3 powder were studied with respect to the effects of not only MgO doping but also atmosphere on both densification and grain growth. Controversial results for MgO doping are explained in terms of two roles that MgO can play during these processes: sensitive and insensitive to the experimental procedures. Atmospheres, whether dry or wet, had little influence on densification or grain growth in the early stage. After closed pores appreciably formed, however, both N2 and Ar atmospheres quickly reduced the densification rate.

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Maugeri, Emilio Andrea, Jörg Neuhausen, Borja Gonzalez Prieto, Alexander Aerts, Tania Melo Mendonça, Thierry Stora e Robert Eichler. "Adsorption of volatile polonium species on metals in various gas atmospheres: Part III – Adsorption of volatile polonium on stainless steel 316L". Radiochimica Acta 106, n.º 2 (26 de janeiro de 2018): 125–34. http://dx.doi.org/10.1515/ract-2017-2807.

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AbstractThis article summarizes the results obtained studying the interaction between polonium and stainless steel 316L in different atmospheres by the thermochromatography method. This issue is particularly important in terms of licensing of the MYRRHA prototype ADS reactor, where highly radiotoxic α-emitting polonium isotopes are produced in lead-bismuth eutectic used as both spallation target material and coolant, while stainless steel 316L is going to be the main structural material. The polonium adsorption enthalpy on stainless steel 316L in inert atmosphere was measured as −147±6 kJ mol−1. The findings obtained using reducing atmospheres show that the affinity of polonium for stainless steel 316L increases with the metallic character of the stainless steel surface. The presence of moisture in inert and reducing atmosphere does not significantly influence the polonium adsorption. Oxidizing atmospheres induce the formation of polonium dioxide which has a stronger interaction with the stainless steel 316L, with an adsorption enthalpy of −225±6 kJ mol−1. A prolonged exposure of the stainless steel to strong oxidants, such as pure oxygen, reduces the metallic character of the stainless steel surface and, consequently, its affinity to the polonium oxide. Furthermore, it was found that in all experiments at least 5 ppm of the total polonium present in the starting material were not retained on the stainless steel 316L surface at all.

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Hall, Sawyer, Joshua Krissansen-Totton, Tyler Robinson, Arnaud Salvador e Jonathan J. Fortney. "Constraining Background N₂ Inventories on Directly Imaged Terrestrial Exoplanets to Rule Out O₂ False Positives". Astronomical Journal 166, n.º 6 (20 de novembro de 2023): 254. http://dx.doi.org/10.3847/1538-3881/ad03e9.

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Abstract Direct imaging spectroscopy with future space-based telescopes will constrain terrestrial planet atmospheric composition and potentially detect biosignature gases. One promising indication of life is abundant atmospheric O2. However, various non-biological processes could also lead to O2 accumulation in the atmospheres of potentially habitable planets around Sun-like stars. In particular, the absence of non-condensible background gases such as N2 could result in appreciable H escape and abiotic O2 buildup, so identifying background atmosphere composition is crucial for contextualizing any O2 detections. Here, we perform retrievals on simulated directly imaged terrestrial planets using rfast, a new exoplanet atmospheric retrieval suite with direct imaging analysis capabilities. By simulating Earth-analog retrievals for varied atmospheric compositions, cloud properties, and surface pressures, we determine what wavelength range, spectral resolution, and signal-to-noise ratio (S/N) are necessary to constrain background gases’ identity and abundance. We find N2 backgrounds can be uniquely identified with S/N ∼ 20 observations, provided that wavelength coverage extends beyond ∼1.6 μm to rule out CO-dominated atmospheres. Additionally, there is a low probability of O2-dominated atmospheres due to an O2–N2 degeneracy that is only totally ruled out at S/N ∼ 40. If wavelength coverage is limited to 0.2–1.1 μm, then although all other cosmochemically plausible backgrounds can be readily excluded, N2 and CO backgrounds cannot be distinguished. Overall, our simulated retrievals and associated integration time calculations suggest that near-infrared coverage to at least 1.6 μm and apertures approaching 8 m are needed to confidently rule out O2 biosignature false positives within feasible integration times.

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Yan, F., R. A. E. Fosbury, M. G. Petr-Gotzens, G. Zhao, W. Wang, L. Wang, Y. Liu e E. Pallé. "High-resolution transmission spectrum of the Earth's atmosphere-seeing Earth as an exoplanet using a lunar eclipse". International Journal of Astrobiology 14, n.º 2 (12 de setembro de 2014): 255–66. http://dx.doi.org/10.1017/s1473550414000172.

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AbstractWith the rapid developments in the exoplanet field, more and more terrestrial exoplanets are being detected. Characterizing their atmospheres using transit observations will become a key datum in the quest for detecting an Earth-like exoplanet. The atmospheric transmission spectrum of our Earth will be an ideal template for comparison with future exo-Earth candidates. By observing a lunar eclipse, which offers a similar configuration to that of an exoplanet transit, we have obtained a high-resolution and high signal-to-noise ratio (SNR) transmission spectrum of the Earth's atmosphere. This observation was performed with the High Resolution Spectrograph at Xinglong Station, China during the total lunar eclipse in December 2011. We compare the observed transmission spectrum with our atmospheric model, and determine the characteristics of the various atmospheric species in detail. In the transmission spectrum, O2, O3, O2 · O2, NO2 and H2O are detected, and their column densities are measured and compared with the satellites data. The visible Chappuis band of ozone produces the most prominent absorption feature, which suggests that ozone is a promising molecule for the future exo-Earth characterization. Due to the high resolution and high SNR of our spectrum, several novel details of the Earth atmosphere's transmission spectrum are presented. The individual O2 lines are resolved and O2 isotopes are clearly detected. Our new observations do not confirm the absorption features of Ca II or Na I which have been reported in previous lunar eclipse observations. However, features in these and some other strong Fraunhofer line positions do occur in the observed spectrum. We propose that these are due to a Raman-scattered component in the forward-scattered sunlight appearing in the lunar umbral spectrum. Water vapour absorption is found to be rather weak in our spectrum because the atmosphere we probed is relatively dry, which prompts us to discuss the detectability of water vapour in Earth-like exoplanet atmospheres.

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TADA, HIROKAZU, HIROSHI TOUDA, MASAKI TAKADA e KAZUMI MATSUSHIGE. "Field Effect Mobility of F16PcCu Films in Various Gas Atmospheres". Journal of Porphyrins and Phthalocyanines 03, n.º 07 (outubro de 1999): 667–71. http://dx.doi.org/10.1002/(sici)1099-1409(199908/10)3:6/7<667::aid-jpp191>3.0.co;2-y.

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The electron mobility of hexadecafluorophthalocyaninato-copper ( F 16 PcCu ) films was evaluated based on field effect measurements in vacuum and in various gas atmospheres. An Arrhenius plot of the mobility showed that the carrier transport followed a thermally activated hopping mechanism with an activation energy of 0.28 eV. The mobility evaluated for freshly prepared films in ultrahigh vacuum was 2.0 × 10−3 cm 2 V −1 s −1 at room temperature. The electrical conductivity and carrier density were 4.4 × 10−5 S cm −1 and 1.4 × 1017 cm −3 respectively. The high carrier density indicated the existence of impurities acting as electron donors in the films. The field effect carrier mobility increased to 5.7 × 10−3 cm 2 V −1 s −1 in NH 3 atmosphere (100%, 1 atm) and decreased by 75% in the presence of O 2 gas (100%, 1 atm). A quick recovery of mobility was observed when the gas molecules were evacuated, indicating a low capability of gas adsorption.

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Kupka, F. "New models for the convective flux in stellar atmospheres". Symposium - International Astronomical Union 176 (1996): 557–64. http://dx.doi.org/10.1017/s0074180900083583.

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Over the past decades various forms of the mixing length theory (MLT) have been used to describe convection in stellar atmospheres. Recent advances in turbulence theory now allow for major improvements in modelling thermal convection. We review several models for convection which have been derived from turbulence theory, and describe one of them, the “CM model”, in detail. The CM model has been used in several stellar evolution and helioseismology codes during the last four years and has now been applied to model atmospheres. An overwiew comparing stellar atmosphere models based on the CM formulation with its MLT predecessors indicates improvements on model atmospheres for A and F stars.

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Li, Jie, Zhigang Li, Dandan Wang e Linqiang Mao. "Volatilization Characteristic of Chloride Salts During the Production of Fired Brick Under Different Atmospheres". Sustainability 17, n.º 3 (29 de janeiro de 2025): 1110. https://doi.org/10.3390/su17031110.

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The behavior of chloride (Cl) salts in high-temperature environments is critical for various industrial processes, including waste treatment and material synthesis. However, the influence of different atmospheric conditions on the volatilization and interaction of Cl salts with clay minerals remains poorly understood. Previous studies have primarily focused on individual salt types under limited conditions, leaving a gap in the comprehensive understanding of how atmosphere composition affects Cl salt volatilization at high temperatures. This work addresses this gap by systematically investigating the volatilization behaviors of NaCl, KCl, and CaCl2 in different atmospheres (air, N2(g), NH3(g), and H2O(g)) across temperatures from 750 to 1050 °C. The results revealed significant differences in volatilization rates, with H2O(g) atmosphere significantly enhancing Cl volatilization, especially for NaCl and KCl, while CaCl2 showed notably lower volatilization. N2(g) and NH3(g) atmospheres exhibit a similar, moderate effect on Cl volatilization, while the air atmosphere suppressed Cl volatilization due to the formation of stable oxide structures. Thermodynamic simulations confirmed the formation of HCl(g) as the primary volatile species, with metal cations forming stable silicates and feldspar compounds with clay minerals. DFT calculations highlighted that H2O(g) lowers the energy barrier for chloride salt decomposition, accelerating volatilization by weakening the bond between metal cations and Cl ions. These findings provide valuable insights into the impact of atmospheric conditions on the volatilization of Cl salts in high-temperature environments.

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Grant, David, Nikole K. Lewis, Hannah R. Wakeford, Natasha E. Batalha, Ana Glidden, Jayesh Goyal, Elijah Mullens et al. "JWST-TST DREAMS: Quartz Clouds in the Atmosphere of WASP-17b". Astrophysical Journal Letters 956, n.º 2 (1 de outubro de 2023): L29. http://dx.doi.org/10.3847/2041-8213/acfc3b.

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Abstract Clouds are prevalent in many of the exoplanet atmospheres that have been observed to date. For transiting exoplanets, we know if clouds are present because they mute spectral features and cause wavelength-dependent scattering. While the exact composition of these clouds is largely unknown, this information is vital to understanding the chemistry and energy budget of planetary atmospheres. In this work, we observe one transit of the hot Jupiter WASP-17b with JWST’s Mid-Infrared Instrument Low Resolution Spectrometer and generate a transmission spectrum from 5 to 12 μm. These wavelengths allow us to probe absorption due to the vibrational modes of various predicted cloud species. Our transmission spectrum shows additional opacity centered at 8.6 μm, and detailed atmospheric modeling and retrievals identify this feature as SiO2(s) (quartz) clouds. The SiO2(s) clouds model is preferred at 3.5–4.2σ versus a cloud-free model and at 2.6σ versus a generic aerosol prescription. We find the SiO2(s) clouds are composed of small ∼0.01 μm particles, which extend to high altitudes in the atmosphere. The atmosphere also shows a depletion of H2O, a finding consistent with the formation of high-temperature aerosols from oxygen-rich species. This work is part of a series of studies by our JWST Telescope Scientist Team (JWST-TST), in which we will use Guaranteed Time Observations to perform Deep Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy (DREAMS).

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Ih, Jegug, Eliza M. R. Kempton, Emily A. Whittaker e Madeline Lessard. "Constraining the Thickness of TRAPPIST-1 b’s Atmosphere from Its JWST Secondary Eclipse Observation at 15 μm". Astrophysical Journal Letters 952, n.º 1 (1 de julho de 2023): L4. http://dx.doi.org/10.3847/2041-8213/ace03b.

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Abstract Recently, the first JWST measurement of thermal emission from a rocky exoplanet was reported. The inferred dayside brightness temperature of TRAPPIST-1 b at 15 μm is consistent with the planet having no atmosphere and therefore no mechanism by which to circulate heat to its nightside. In this Letter, we compare TRAPPIST-1 b's measured secondary eclipse depth to predictions from a suite of self-consistent radiative-convective equilibrium models in order to quantify the maximum atmospheric thickness consistent with the observation. We find that plausible atmospheres (i.e., those that contain at least 100 ppm CO2) with surface pressures greater than 0.3 bar are ruled out at 3σ, regardless of the choice of background atmosphere, and a Mars-like thin atmosphere with surface pressure 6.5 mbar composed entirely of CO2 is also ruled out at 3σ. Thicker atmospheres of up to 10 bar (100 bar) are consistent with the data at 1σ (3σ) only if the atmosphere lacks any strong absorbers across the mid-IR wavelength range—a scenario that we deem unlikely. We additionally model the emission spectra for bare-rock planets of various compositions. We find that a basaltic, metal-rich, and Fe-oxidized surface best matches the measured eclipse depth to within 1σ, and the best-fit gray albedo is 0.02 ± 0.11. We conclude that planned secondary eclipse observations at 12.8 μm will serve to validate TRAPPIST-1 b's high observed brightness temperature, but are unlikely to further distinguish among the consistent atmospheric and bare-rock scenarios.

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Yang, Li Xiang, e Evan Matthews. "Sintering Reactions of Magnetite Concentrates under Various Atmospheres." ISIJ International 37, n.º 11 (1997): 1057–65. http://dx.doi.org/10.2355/isijinternational.37.1057.

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Arakawa, Tsuyoshi, Nobuya Suezawa, Gin‐ya Adachi e Jiro Shiokawa. "Observation of electroluminescence of ZnS:TbF3under various gaseous atmospheres". Applied Physics Letters 51, n.º 26 (28 de dezembro de 1987): 2181–82. http://dx.doi.org/10.1063/1.98932.

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Milicevic, Dejan, e Edin Suljovrujic. "Properties of isotactic polypropylene irradiated in various atmospheres". Chemical Industry 64, n.º 3 (2010): 201–8. http://dx.doi.org/10.2298/hemind091221029m.

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In this paper, changes in structure and physical properties of stabilized isotactic polypropylene (iPP) were created by gamma irradiation, up to a dose of 700 kGy, in different media: air, deionized distilled (DD) water and acetylene. Two main effects occur when polyolefins, such as iPP, are subjected to ionizing radiation: crosslinking and scission of macromolecules. The domination of one or the other of these competitive processes is determined by both the structural peculiarities of the polymers and the experimental irradiation conditions. Gel and infrared (IR) spectroscopy measurements were used to determine the changes in the degree of network formation and oxidative degradation, respectively. Sol-gel analysis was studied in detail using the Charlesby-Pinner (C-P) equation. The radiation-induced changes in the structure and evolution of oxygen-containing species were also studied through dielectric loss (tan ?) analysis in a wide temperature and/or frequency range. Evolution of low temperature dielectric relaxations with gamma irradiation was investigated. The results showed that degradation was the major reaction in the initial step of irradiation, no matter what the atmosphere was. The C-P equation seemed applicable when stabilized iPP was irradiated within a certain dose range in various atmospheres. The iPP irradiated in acetylene/air had the lowest/highest values for oxidation level, dielectric losses, Dg and G(s)/G(x) values. The calculated Dg values are 1.5 and 5 times larger for the irradiation in DD water and air than for the acetylene. Furthermore, our data confirm that oxidation strongly affects the gel point but has a much lower effect on the G(S)/G(X) ratio. In the case of dielectric relaxation measurements, the connection between the oxidative degradation and dielectric properties is well established and is in good agreement with IR spectroscopy measurements. The amount of carbonyl, hydroperoxide and other polar groups is much higher for the irradiation in air than in other media, leading to higher dielectric losses. Disappearance of low temperature (? and ?) relaxations with gamma radiation confirmed great sensitivity of iPP structure to radiation-induced changes. Complete ?vanishing? of the ? relaxation in iPP samples irradiated in air is connected with a large radiation-induced oxidative degradation in this medium. Similar crosslinking, oxidation and dielectric behaviour was observed for the samples irradiated in water and acetylene, indicating DD water as a good crosslinking medium.

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Lee, M. S., e H. K. Lee. "Superconducting transitions of LuBa2Cu3O7-zheated under various atmospheres". Progress in Superconductivity and Cryogenics 16, n.º 1 (31 de março de 2014): 6–8. http://dx.doi.org/10.9714/psac.2014.16.1.006.

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Sata, T. "Coloration of molten aluminium surface in various atmospheres". Journal of Materials Science 29, n.º 1 (1994): 129–35. http://dx.doi.org/10.1007/bf00356583.

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Shinozaki, Kazuo, Toshiyuki Kurosawa, Atushi Nanjyo, Nobuyasu Miztani e Masanori Kato. "Chemical stability of YBa2Cu3O7-x to various atmospheres". Thermochimica Acta 136 (dezembro de 1988): 297–306. http://dx.doi.org/10.1016/0040-6031(88)87448-3.

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Zhang, Yujuan, Kazuo Shinozaki, Nobuyasu Mizutani e Masanori Kato. "Chemical stability of BaCuO2 in various humid atmospheres". Thermochimica Acta 153 (novembro de 1989): 63–76. http://dx.doi.org/10.1016/0040-6031(89)85422-x.

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Saquet, Adriano Arriel. "Storability of ‘Conference’ Pear Under Various Controlled Atmospheres". Erwerbs-Obstbau 60, n.º 4 (7 de fevereiro de 2018): 275–80. http://dx.doi.org/10.1007/s10341-018-0369-7.

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Gloor, S., S. M. Pimenov, E. D. Obraztsova, W. Lüthy e H. P. Weber. "Laser ablation of diamond films in various atmospheres". Diamond and Related Materials 7, n.º 2-5 (fevereiro de 1998): 607–11. http://dx.doi.org/10.1016/s0925-9635(97)00288-4.

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Zong, Yan Bing, Zhao Bo Liu, Jun Jie Hou e Hong Xu Li. "Investigation of Glass-Ceramics Based on Steel Slag under Various Sintering Atmospheres". Advanced Materials Research 1065-1069 (dezembro de 2014): 1784–90. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.1784.

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Slag glass-ceramics were successfully prepared by cold pressing sintering method in different atmospheres from metallurgical solid wastes. The evolution of crystal microstructure and crystalline phase transition of slag glass-ceramics was investigated by thermo-gravimetric analysis (TG-DTA), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) coupled with Energy Dispersive X-ray spectrometer (EDX). The results indicate that the Na2O composition plays the role of decreasing the crystallization temperature to some extent. Iron oxides make the glass frits have a high driving force to crystallize. This oxidation of ferrum will postpone the process of densification and deteriorate the mechanical properties of product. On the other hand, the slag glass-ceramic products can obtain novel mechanical performance when the samples were sintered under nitrogen atmosphere.

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35

Scardaci, Vittorio, Luca Fichera, Maria E. Fragalà, Nunzio Tuccitto, Giovanni Marletta e Giuseppe Compagnini. "Reduction of Graphene Oxide by Laser Scribing in Different Atmospheres and Application in Humidity Sensing". Journal of Nanomaterials 2020 (5 de outubro de 2020): 1–7. http://dx.doi.org/10.1155/2020/4946954.

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Laser scribing, by far proposed as a method for efficiently transforming graphene oxide into reduced graphene, has been employed, using a CW laser beam, to study the modifications of graphene oxide scribed under different controlled atmospheres, including air, N2, Ar, and a 95 : 5 (v/v) Ar/H2 mixture. We have found that laser scribing effects, including chemical composition, order degree, and electrical properties, strongly depend upon the atmosphere during the irradiation. The electrical properties of the various materials, obtained in different atmospheres, have been evaluated with respect to the sensing properties towards humidity, the materials produced in pure Argon yielding the highest sensitivity and the fastest response, while related Raman microspectroscopy measurements showed that both Ar and Ar-H2 mixture produce the highest order among the various samples. The results stress the importance and the potentialities of controlling the irradiation atmosphere in order to tune the composition and electrical properties of the laser-scribed graphene oxide materials.

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36

Rajpurohit, A. S., F. Allard, D. Homeier, O. Mousis e S. Rajpurohit. "Dayside thermal inversion in the atmosphere of WASP-19b". Astronomy & Astrophysics 642 (outubro de 2020): A39. http://dx.doi.org/10.1051/0004-6361/202038302.

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Context. Observations of ultra-hot Jupiters indicate the existence of thermal inversion in their atmospheres, with dayside temperatures greater than 2200 K. Various physical mechanisms such as non-local thermal equilibrium, cloud formation, disequilibrium chemistry, ionisation, hydrodynamic waves, and associated energy have been omitted in previous spectral retrievals, while they play an important role in the thermal structure of their upper atmospheres. Aims. We aim to explore the atmospheric properties of WASP-19b to understand its largely featureless thermal spectra using a state-of-the-art atmosphere code that includes a detailed treatment of the most important physical and chemical processes at play in such atmospheres. Methods. We used the one-dimensional line-by-line radiative transfer code PHOENIX in its spherical symmetry configuration including the BT-Settl cloud model and C/O disequilibrium chemistry to analyse the observed thermal spectrum of WASP-19b. Results. We find evidence for a thermal inversion in the dayside atmosphere of the highly irradiated ultra-hot Jupiter WASP-19b, with Teq ~ 2700 K. At these high temperatures we find that H2O dissociates thermally at pressures below 10−2 bar. The inverted temperature-pressure profiles of WASP-19b show evidence of CO emission features at 4.5 μm in its secondary eclipse spectra. Conclusions. We find that the atmosphere of WASP-19b is thermally inverted. We infer that the thermal inversion is due to the strong impinging radiation. We show that H2O is partially dissociated in the upper atmosphere above about τ = 10−2, but is still a significant contributor to the infrared opacity, dominated by CO. The high-temperature and low-density conditions cause H2O to have a flatter opacity profile than in non-irradiated brown dwarfs. Altogether these factors make H2O more difficult to identify in WASP-19b. We suggest that the state-of-the-art PHOENIX model atmosphere code is well suited to the study of this new class of extrasolar planets, ultra-hot Jupiters.

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Moritz, Philipp, Lienhard Wegewitz e Wolfgang Maus-Friedrichs. "Dependence of the Molecular Interactions Between Cyanoacrylate and Native Copper Surfaces on the Process Atmosphere". Adhesives 1, n.º 1 (24 de dezembro de 2024): 1. https://doi.org/10.3390/adhesives1010001.

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Cyanoacrylates, known for their rapid polymerization and strong bonding capabilities, are widely used in industrial and medical applications. This study investigates the impacts of different process atmospheres with varying water and oxygen contents—air, argon, and argon/silane—on the curing and adhesion mechanisms of cyanoacrylate adhesives on oxidized copper substrates. Raman spectroscopy indicated that the curing process in argon and argon/silane atmospheres was slower compared to ambient air, likely due to the reduced moisture content of the atmosphere. However, the degree of curing and the inter- and intramolecular interactions within the adhesive volume showed no significant differences across atmospheres. X-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy (IRRAS) revealed that strong ionic interactions between cyanoacrylate and the copper surface oxide were absent in the low-moisture argon atmosphere. The introduction of silane resulted in the formation of silicon oxides and other silane-derived compounds, which probably contributed to the formation of these ionic interactions, similar to those observed in air. This study highlights the critical influence of the surrounding atmosphere on the adhesive properties of cyanoacrylates, with implications for optimizing bonding processes in various environments.

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Michels, Christoph, e Chris Steyaert. "By accident and by design: Composing affective atmospheres in an urban art intervention". Organization 24, n.º 1 (janeiro de 2017): 79–104. http://dx.doi.org/10.1177/1350508416668190.

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This article argues that the notion of affective atmosphere provides a privileged access to the study of organizational affect as it relates to a spatial ontology of ‘being-together-in-a-sphere’. Drawing on the study of affective atmospheres in philosophy and cultural geography, we develop a conceptual positioning from which to analyze a musical intervention in the streets and squares of Berlin. The study traces the preparation and enactment of a 2-day music event that breaks with the emotional experience of a ‘mainstream’ classical concert, and instead intervenes in urban atmospheres by mingling music performances with everyday urban life in an attempt to affect chance spectators. Tracing how the concert’s atmospheres emerged through a series of encounters between various bodies and their specific affective capacities, the analysis emphasizes the tension between the possibility of designing and crafting atmospheres and its emergence in erratic, ephemeral, and excessive ways. Therefore, we propose that affective atmospheres make perceptible the potentialities of organizational space and give scope to our feelings as we experience their spatial recomposition. In the conclusion, we emphasize affective atmospheres as a key concept for the critical study of affect, as it advances a politics that attends to new possibilities of feeling and acting collectively in spaces of organizing.

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Shulyak, D., L. M. Lara, M. Rengel e N. E. Nèmec. "Stellar impact on disequilibrium chemistry and observed spectra of hot Jupiter atmospheres". Astronomy & Astrophysics 639 (julho de 2020): A48. http://dx.doi.org/10.1051/0004-6361/201937210.

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Aims. We study the effect of disequilibrium processes (photochemistry and vertical transport) on mixing ratio profiles of neutral species and on the simulated spectra of a hot Jupiter exoplanet that orbits stars of various spectral types. We additionally address the impact of stellar activity that should be present, to various degrees, in all stars with convective envelopes. Methods. We used the VULCAN chemical kinetic code to compute number densities of species in irradiated planetary atmospheres. The temperature-pressure profile of the atmosphere was computed with the HELIOS code. We also utilized the τ-REx forward model to predict the spectra of planets in primary and secondary eclipses. In order to account for the stellar activity, we made use of the observed solar extreme ultraviolet (XUV) spectrum taken from Virtual Planetary Laboratory as a proxy for an active sun-like star. Results. We find large changes in the mixing ratios of most chemical species in planets orbiting A-type stars, which radiate strong XUV flux thereby inducing a very effective photodissociation. For some species, these changes can propagate very deep into the planetary atmosphere to pressures of around 1 bar. To observe disequilibrium chemistry we favor hot Jupiters with temperatures Teq = 1000 K and ultra-hot Jupiters, with Teq ≈ 3000 K,which also have temperature inversion in their atmospheres. On the other hand, disequilibrium calculations predict no noticeable changes in spectra of planets with intermediate temperatures. We also show that stellar activity similar to that of the modern Sun drives important changes in mixing ratio profiles of atmospheric species. However, these changes take place at very high atmospheric altitudes and thus do not affect predicted spectra. Finally, we estimate that the effect of disequilibrium chemistry in planets orbiting nearby bright stars could be robustly detected and studied with future missions with spectroscopic capabilities in infrared such as James Webb Space Telescope and ARIEL.

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Păun, Florin Adrian, e Dan Gabor. "Application of flammability testing methods for conveyor belts intended for use in potentially explosive atmospheres in order to select suitable types for field application". MATEC Web of Conferences 354 (2022): 00045. http://dx.doi.org/10.1051/matecconf/202235400045.

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The conveyor belts are widely used and can be found, for example, in the underground and surface mining industry as well as in other industries involving the transport of various products, materials, etc. The need to ensure the transport of various products, materials, involves the use of conveyor belts in normal environments as well as in environments with a potentially explosive atmosphere. When used in potentially explosive atmospheres, conveyor belts shall not be sources of ignition for the explosive atmospheres generated by gases, vapors, flammable mists and/or combustible dusts in the mixture with the air. This involves the use of conveyor belts in a particular construction, compliance with the applicable essential safety and health requirements as well as granting a special attention to the identification/selection of types suitable for the specific field application. The purpose of the paper is to highlight the importance of testing by accredited laboratory tests, the flammability properties of conveyor belts intended for use in potentially explosive atmospheres, in order to easily identify/select, by end users, the types of conveyor belts adequate for specific application.

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Bisikalo, Dmitry V., e Valery I. Shematovich. "Neutral atmospheric escape in the Solar and extrasolar planetary systems". Proceedings of the International Astronomical Union 14, S345 (agosto de 2018): 168–71. http://dx.doi.org/10.1017/s174392131800858x.

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AbstractNew data obtained by space missions to various objects in the Solar system and observations of the outer Solar system and exoplanets by space and ground-based telescopes allowed us to conclude that the atmospheric escape plays an important role in the evolution of the terrestrial planets in the Solar system. We present the recent results of application of the kinetic approach to the problem of neutral escape from planetary atmospheres. As an example, the recent measurements by Mars Express and MAVEN spacecraft are compared with the calculations of neutral escape with the aim to understand the atmospheric loss at Mars. Also the recent calculations of the mass-loss rates of the hot Neptune and Jupiter atmospheres are presented.

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Jamaludin, Siti Nur Sakinah, Shahnor Basri, Faizal Mustapha, Dewan Muhammad Nuruzzaman, Muhammad Ihsan Abdul Latiff e Noor Mazni Ismail. "Phase Contamination Characterization of Stepwise-Built Functionally Graded Hydroxyapatite/Titanium (HA/Ti) Sintered under Various Atmospheres". Materials Science Forum 889 (março de 2017): 90–95. http://dx.doi.org/10.4028/www.scientific.net/msf.889.90.

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Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) test were utilized to detect the phase transformation of a HA/Ti Functionally Graded Material (FGM) prepared via Powder Metallurgy (PM) technique. The effects of oxygen (O2), nitrogen (N2), forming (N2+H2) and Argon (Ar) sintering atmospheres on the FGM specimens were examined by considering the gas flowing duration. It was found that the original metallurgical profile of pure Ti in HA/Ti FGM sintered under N2 atmosphere was almost preserved. However the carburization of the pure Ti was observed on the specimen. Medium alkyl halides (C-Br) and alkenes (-C=C-) stretches were detected, producing the dominant elements in the pure Ti layer of the specimen. The almost stable constituent element remains in the specimen sintered under flowing N2+H2 atmosphere as detected by XRD result. This proved the significance of controlling the sintering atmosphere during the entire sintering process. The results achieved reveal the high tendency of Ti and HA elements to react with the sintering environment, thus very precise furnace with controllable atmosphere is crucial for the fabrication of the HA/Ti FGM.

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Kanari, Ndue, Nour-Eddine Menad, Etleva Ostrosi, Seit Shallari, Frederic Diot, Eric Allain e Jacques Yvon. "Thermal Behavior of Hydrated Iron Sulfate in Various Atmospheres". Metals 8, n.º 12 (19 de dezembro de 2018): 1084. http://dx.doi.org/10.3390/met8121084.

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Iron sulfate, in particular FeSO4·7H2O, is derived from titanium dioxide production and the steel pickling process. Regarding TiO2 manufacturing, the amount of the resultant FeSO4·7H2O can be as high as 6 tons per ton of produced TiO2, leading to a huge amount of ferrous sulfate heptahydrate, which is considered an environmental and economic concern for the titanium dioxide industry in European countries. The present paper focuses on the thermal treatment of ferrous sulfate (heptahydrate and monohydrate) samples under different conditions. Nonisothermal thermogravimetric (TG) analysis was used to study the behavior of iron sulfate samples at temperatures of up to 1000 °C in Cl2 + O2, O2, and N2 atmospheres. Results showed that the dehydration of iron sulfate heptahydrate in nitrogen started at room temperature and resulted in iron sulfate tetrahydrate (FeSO4·4H2O). The ferrous sulfate monohydrate (FeSO4·H2O) was formed at temperatures close to 150 °C, while the anhydrous ferrous sulfate (FeSO4) was obtained when the samples were heated in nitrogen at over 225 °C. The kinetic features of FeSO4 decomposition into Fe2O3 were revealed under isothermal conditions at temperatures ranging from 500 to 575 °C. The decomposition of iron sulfate was characterized by an apparent activation energy of around 250 kJ/mol, indicating a significant temperature effect on the decomposition process. The obtained powder iron oxide could be directed to the agglomeration unit of iron and the steelmaking process.

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Suljovrujic, E. "Post-irradiation effects in polyethylenes irradiated under various atmospheres". Radiation Physics and Chemistry 89 (agosto de 2013): 43–50. http://dx.doi.org/10.1016/j.radphyschem.2013.04.003.

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Guo, Hongyu, Zhixiang Gao, Daping Xia, Xiangju Yin, Jianbo Jia e Yunlong Dou. "Biological methanation of coal in various atmospheres containing CO2". Fuel 242 (abril de 2019): 334–42. http://dx.doi.org/10.1016/j.fuel.2019.01.036.

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OYA, Asao, Yoshiaki KAWAI e Sugio OTANI. "Carbothermal Reduction of Saponite/Acriflavine Complex under Various Atmospheres". Journal of the Ceramic Association, Japan 95, n.º 1100 (1987): 369–73. http://dx.doi.org/10.2109/jcersj1950.95.1100_369.

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Muraishi, Kazuo, e Yukihiko Suzuki. "The thermal behaviour of dicarboxylic acids in various atmospheres". Thermochimica Acta 232, n.º 2 (fevereiro de 1994): 195–203. http://dx.doi.org/10.1016/0040-6031(94)80059-6.

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Sata, Toshiyuki. "High-temperature vaporizations from eucryptite ceramics in various atmospheres". Ceramics International 16, n.º 5 (janeiro de 1990): 263–72. http://dx.doi.org/10.1016/0272-8842(90)90038-h.

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Bowen, G. H. "Model Atmospheres with Periodic Shocks". International Astronomical Union Colloquium 106 (1989): 269–83. http://dx.doi.org/10.1017/s0252921100063090.

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AbstractThe pulsation of a long-period variable star generates shock waves which dramatically affect the structure of the star's atmosphere and produce conditions that lead to rapid mass loss. Numerical modeling of atmospheres with periodic shocks is being pursued to increase our understanding of the processes involved and of the evolutionary consequences for the stars. It is characteristic of these complex dynamical systems that most effects result from the interaction of various time-dependent processes. For example, rapid mass loss in the models is a joint consequence of the enormous extension of the atmosphere caused by shocks, and of radiation pressure on grains formed in the cool outer region; it is also affected by thermal relaxation processes, which determine the temperature distribution. The progress and significance of these modeling calculations will be reviewed.

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Luo, J., H. Q. He, G. S. Tong e Jiao Li. "Quantifying the Key Factors Affecting the Escape of Planetary Atmospheres". Astrophysical Journal 951, n.º 2 (1 de julho de 2023): 136. http://dx.doi.org/10.3847/1538-4357/acd330.

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Abstract The habitability of Earth-like planets is an increasingly important subject in astrophysics and in planetary sciences. Atmospheric escape plays a vital role in the evolution of the habitability of Earth-like planets. By systematically analyzing the numerical simulation results of the interactions between the planetary atmospheres and the stellar winds, in this work, we evaluate various factors related to the atmospheric nonthermal ion escape rates, including planetary parameters (e.g., mass, density, radius, semimajor axis, etc.) and stellar wind parameters (e.g., density, velocity, and interplanetary magnetic field (IMF) strength). Furthermore, we determine and quantify the key factors affecting the planetary atmospheric nonthermal ion escape rates. Our results show that the correlation coefficients between planetary atmospheric nonthermal ion escape rates and stellar wind density, IMF strength, and the ratio of the planetary radius to the planetary semimajor axis are 0.98 (0.88), 0.95 (0.81), and 0.87 (0.59), respectively, in the scenario of maximum (minimum) dynamic wind pressure. This means that the planetary atmospheric nonthermal ion escape rates increase with the increasing stellar wind density, the increasing IMF strength, and the increasing ratio of the planetary radius to the planetary semimajor axis. Generally, the nonthermal ion escape rates of planetary atmospheres are more sensitive to stellar wind parameters than to others. In addition, we determine the functional relations of the above three significant parameters for evaluating and quantifying the effects of such key physical factors on the nonthermal ion escape rates of the planetary atmospheres. Our findings will be very useful for better understanding the key factors that influence the escapes of planetary atmospheres.

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