The State of Cu Promoter Atoms in High-Temperature Shift Catalysts—An in Situ Fluorescence XAFS Study

2001 ◽  
Vol 198 (1) ◽  
pp. 56-65 ◽  
Author(s):  
Peter Kappen ◽  
Jan-Dierk Grunwaldt ◽  
Birgitte S Hammershøi ◽  
Larc Tröger ◽  
Bjerne S Clausen
Keyword(s):  
High Temperature ◽  
Temperature Shift ◽  
The State ◽  
Fluorescence Xafs

D-50 in Situ Characterization of High-Temperature Shift Catalysts

2007 ◽  
Vol 22 (2) ◽  
pp. 190-190
Author(s):  
A. M. Molenbroek ◽  
R. E. Johnsen ◽  
K. Sta˚hl
Keyword(s):  
High Temperature ◽  
Temperature Shift ◽  
In Situ Characterization

XRPD/TEM studies of model high-temperature shift catalysts

2006 ◽  
Vol 39 (4) ◽  
pp. 519-526 ◽  
Author(s):  
Rune E. Johnsen ◽  
Alfons M. Molenbroek ◽  
Kenny Ståhl
Keyword(s):  
High Temperature ◽  
Iron Oxide ◽  
Crystallite Size ◽  
Rietveld Method ◽  
Temperature Shift ◽  
Average Crystallite Size ◽  
Model Catalysts ◽  
Crystallite Sizes ◽  
Scherrer Equation

The combination of transmission electron microscopy (TEM) andin situX-ray powder diffraction (XRPD) for the investigation of four model high-temperature shift catalysts makes it possible to obtain and compare information concerning the crystallite and particle shapes and sizes before, during and after the reduction of the synthesized hematite-based model catalyst to the active magnetite-based catalyst. Two chromium-containing iron oxide model catalysts and two pure iron oxide model catalysts were synthesized from hydrated chloride or nitrate salts, resulting in particles with different shapes and sizes. The average crystallite sizes of four model catalysts were determined by XRPD using the Scherrer equation before and after the reduction. The crystallite sizes determined before the reduction were compared with particles sizes determined from TEM images of the same samples. These sizes were generally in good agreement. By using the Rietveld method combined with the Scherrer equation and the Lorentzian Scherrer broadening parameters, the development of the average crystallite size during thein situreduction was demonstrated. This showed that the average crystallite size of the remaining hematite increases when the reduction begins. Additionally, the average crystallite sizes of the reduced samples showed that the chromium-containing model catalysts have the smallest increase in the overall crystallite size.

The reaction of amorphous Ni-Nb films with Si in the presence of a native SiO2 layer

1990 ◽  
Vol 48 (4) ◽  
pp. 664-665
Author(s):  
N. Rozhanski ◽  
A. Barg
Keyword(s):  
High Temperature ◽  
Crystallization Temperature ◽  
Diffusion Barriers ◽  
Sio2 Layer ◽  
Si Substrate ◽  
Cross Sectional ◽  
Plan View ◽  
Temperature Range ◽  
Sputter Deposited

Amorphous Ni-Nb alloys are of potential interest as diffusion barriers for high temperature metallization for VLSI. In the present work amorphous Ni-Nb films were sputter deposited on Si(100) and their interaction with a substrate was studied in the temperature range (200-700)°C. The crystallization of films was observed on the plan-view specimens heated in-situ in Philips-400ST microscope. Cross-sectional objects were prepared to study the structure of interfaces.The crystallization temperature of Ni5 0 Ni5 0 and Ni8 0 Nb2 0 films was found to be equal to 675°C and 525°C correspondingly. The crystallization of Ni5 0 Ni5 0 films is followed by the formation of Ni6Nb7 and Ni3Nb nucleus. Ni8 0Nb2 0 films crystallise with the formation of Ni and Ni3Nb crystals. No interaction of both films with Si substrate was observed on plan-view specimens up to 700°C, that is due to the barrier action of the native SiO2 layer.

A Litreary Review of Vishama Jwara and its principle of treatment

2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Dr.Saurabh Parauha ◽  
Hullur M. A. ◽  
Prashanth A. S.
Keyword(s):  
High Temperature ◽  
Body Temperature ◽  
The State ◽  
The Body ◽  
Cardinal Symptoms

In Ayurveda, Jwara is not merely the concept of raised body temperature, but as is said in Charaka Samhita, 'Deha- Indriya- Manah- Santap' is the cardinal symptoms of Jwara. This can be defined as the state where the body, mind as well as sense oragans suffer due to the high temperature. Vishamajwara is a type of fever, which is described in all Ayurvedic texts. Charaka mentioned Vishamajwara and Chakrapani have commented on Vishamajwara as Bhutanubanda, Susruta affirmed that Aagantuchhanubhandohi praysho Vishamajware. Madhavakara has also recognised Vishamajwara as Bhutabhishangajanya (infected by microorganism). Vishamajwara is irregular (inconsistent) in it's Arambha (nature of onset commitment), Kriya (action production of symptoms) and Kala (time of appearance) and possesses Anushanga (persistence for long periods). The treatment of this disease depends upon Vegavastha and Avegavastha of Jwara. Various Shodhana and Shamana procedures are mentioned in classics to treat Visham Jwara.

In-situ reaction between arsenic/selenium and minerals in fly ash at high temperature during blended coal combustion

2020 ◽  
Vol 48 (11) ◽  
pp. 1356-1364
Author(s):  
Jun HAN ◽  
Yang-shuo LIANG ◽  
Bo ZHAO ◽  
Zi-jiang XIONG ◽  
Lin-bo QIN ◽  
...  
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Coal Combustion ◽  
In Situ Reaction ◽  
Blended Coal

scholarly journals Venus: key to understanding the evolution of terrestrial planets

2021 ◽  
Author(s):  
Colin F. Wilson ◽  
Thomas Widemann ◽  
Richard Ghail
Keyword(s):  
High Temperature ◽  
High Resolution ◽  
Radar Imaging ◽  
Space Science ◽  
Interior Surface ◽  
Extended Surface ◽  
Earth Like Planets ◽  
Orbital Mission

AbstractIn this paper, originally submitted in answer to ESA’s “Voyage 2050” call to shape the agency’s space science missions in the 2035–2050 timeframe, we emphasize the importance of a Venus exploration programme for the wider goal of understanding the diversity and evolution of habitable planets. Comparing the interior, surface, and atmosphere evolution of Earth, Mars, and Venus is essential to understanding what processes determined habitability of our own planet and Earth-like planets everywhere. This is particularly true in an era where we expect thousands, and then millions, of terrestrial exoplanets to be discovered. Earth and Mars have already dedicated exploration programmes, but our understanding of Venus, particularly of its geology and its history, lags behind. Multiple exploration vehicles will be needed to characterize Venus’ richly varied interior, surface, atmosphere and magnetosphere environments. Between now and 2050 we recommend that ESA launch at least two M-class missions to Venus (in order of priority): a geophysics-focussed orbiter (the currently proposed M5 EnVision orbiter – [1] – or equivalent); and an in situ atmospheric mission (such as the M3 EVE balloon mission – [2]). An in situ and orbital mission could be combined in a single L-class mission, as was argued in responses to the call for L2/L3 themes [3–5]. After these two missions, further priorities include a surface lander demonstrating the high-temperature technologies needed for extended surface missions; and/or a further orbiter with follow-up high-resolution surface radar imaging, and atmospheric and/or ionospheric investigations.

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