Academic literature on the topic 'Hydrogen termination'
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Journal articles on the topic "Hydrogen termination"
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MUBARAK, A. A. KARIM, and MAHMOUD ALELAIMI. "HYDROGEN ADSORPTION ON β-TiAl (001) AND Ni/TiAl (001) SURFACES." Surface Review and Letters 21, no. 03 (June 2014): 1450034. http://dx.doi.org/10.1142/s0218625x14500346.
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In this paper, we present first principles calculations of the energetic, electronic and magnetic properties of the variant termination of TiAl (001) and Ni / TiAl (001) surfaces with and without hydrogen atoms. The calculations have been performed within the density functional theory using full-potential linearized augmented plane wave method. The generalized gradient approximation (GGA) is utilized as the exchange-correlation energy. The octahedral site is the stable absorption site of H atom in the β- TiAl system. This absorption reduces the cohesive energy of β- TiAl system due to increase in the lattice constant. The surface energy for both TiAl (001) terminations is calculated. The stable adsorption site of H atoms on the variant termination of TiAl (001) surface is performed. The adsorption energy of hydrogen on Ti is more energetic than that on Al . The adsorption of H atom on both terminations of H / Ni / TiAl (001) is more preferable at the bridge site. The adsorption energies are enhanced on Ni atom due to the contraction between d- Ni bands and TiAl substrate band.
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Chyan, Oliver M. R., Junjun Wu, and Jin-Jian Chen. "Comparative Studies of Hydrogen Termination on Single-Crystal Silicon Surfaces by FT-IR and Contact-Angle Measurements." Applied Spectroscopy 51, no. 12 (December 1997): 1905–9. http://dx.doi.org/10.1366/0003702971939730.
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The hydrogen termination process on a Si(100) surface has been studied by multiple internal reflection infrared spectroscopy (MIR-IS) and contact-angle measurements. Three main silicon hydride absorption peaks at 2087, 2104, and 2114 cm−1 were found to gradually increase with the hydrofluoric (HF) acid etching. Eventually, a constant peak height was reached as an indication of complete hydrogen termination. Integration of all the surface hydrides absorption peaks (2000 to 2200 cm−1) provides direct quantitative evaluation of the hydrogen termination process. On the other hand, water contact-angle data were shown to consistently lag behind the IR measurement in determining the extent of hydrogen termination on the silicon surface. Analysis of the surface free energy of HF-etched silicon surfaces indicates that the degree of the hydrogen termination determined by water contact-angle measurements is subjected to inaccuracies due to the preferential hydrogen-bonding interaction between the water and silicon surface oxide.
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Hoffmann, René, Armin Kriele, Harald Obloh, Jakob Hees, Marco Wolfer, Waldemar Smirnov, Nianjun Yang, and Christoph E. Nebel. "Electrochemical hydrogen termination of boron-doped diamond." Applied Physics Letters 97, no. 5 (August 2, 2010): 052103. http://dx.doi.org/10.1063/1.3476346.
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Hirama, Kazuyuki, Yoshikatsu Jingu, Masaru Ichikawa, Hitoshi Umezawa, and Hiroshi Kawarada. "DC and RF Performance of Diamond MISFETs with Alumina Gate Insulator." Materials Science Forum 600-603 (September 2008): 1349–51. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.1349.
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We fabricated diamond MISFETs on polycrystalline films using alumina gate insulator. A hole accumulation layer has been utilized as hole current channel. The hydrogen-termination was achieved by remote hydrogen plasma. The sheet resistance strongly depends on the substrate temperature during hydrogen-termination process. The polycrystalline diamond MISFETs showed high drain current density of -650 mA/mm and cut-off frequency of 42 GHz. These values are higher than those of single crystal diamond FETs ever reported.
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Gruntman, Mike. "Ionization of Interstellar Hydrogen Beyond the Termination Shock." Journal of Physics: Conference Series 767 (November 2016): 012012. http://dx.doi.org/10.1088/1742-6596/767/1/012012.
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Mosińska, Lidia, Paweł Popielarski, Kazimierz Fabisiak, and Anna Dychalska. "Effects of hydrogen termination of CVD diamond layers." Optical Materials 101 (March 2020): 109676. http://dx.doi.org/10.1016/j.optmat.2020.109676.
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Seyller, Thomas. "Passivation of hexagonal SiC surfaces by hydrogen termination." Journal of Physics: Condensed Matter 16, no. 17 (April 17, 2004): S1755—S1782. http://dx.doi.org/10.1088/0953-8984/16/17/016.
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Higashi, G. S., Y. J. Chabal, G. W. Trucks, and Krishnan Raghavachari. "Ideal hydrogen termination of the Si (111) surface." Applied Physics Letters 56, no. 7 (February 12, 1990): 656–58. http://dx.doi.org/10.1063/1.102728.
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Wongprasert, Y., and S. B. Pongsai. "Characteristics of Synthesized Diamond Films by Using CACVD Techniques at High Temperatures." Key Engineering Materials 421-422 (December 2009): 131–34. http://dx.doi.org/10.4028/www.scientific.net/kem.421-422.131.
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This paper presents synthesized diamond films by using combustion activated chemical vapor deposition (CACVD) techniques. The characteristics of diamond films have been studied at wide ranges of temperature (30-400°C). The resistance of diamond films has been determined for hydrogen termination times of 5, 10, 15, and 20 minutes, and at the operation temperatures of 500, 600, and 700°C. The investigation found that, at 30°C a synthesized diamond film has a high resistance (1010 ), whereas at high temperatures (100-400°C) the resistance has decreased from 4.04 M to 2.42 M. The result obtained from the hydrogen termination showed that the resistance has decreased by 105-106 (at 30°C). Summarily, it can be stated that the higher the hydrogen termination times and operation temperatures, the lower the resistance of diamond films.
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Kasper, S., M. T. J. van der Meer, A. Mets, R. Zahn, J. S. Sinninghe Damsté, and S. Schouten. "Salinity changes in the Agulhas leakage area recorded by stable hydrogen isotopes of C<sub>37</sub> alkenones during Termination I and II." Climate of the Past 10, no. 1 (February 5, 2014): 251–60. http://dx.doi.org/10.5194/cp-10-251-2014.
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Abstract. At the southern tip of Africa, the Agulhas Current reflects back into the Indian Ocean causing so-called "Agulhas rings" to spin off and release relatively warm and saline water into the South Atlantic Ocean. Previous reconstructions of the dynamics of the Agulhas Current, based on paleo-sea surface temperature and sea surface salinity proxies, inferred that Agulhas leakage from the Indian Ocean to the South Atlantic was reduced during glacial stages as a consequence of shifted wind fields and a northwards migration of the subtropical front. Subsequently, this might have led to a buildup of warm saline water in the southern Indian Ocean. To investigate this latter hypothesis, we reconstructed sea surface salinity changes using alkenone δD, and paleo-sea surface temperature using TEXH86 and UK'37, from two sediment cores (MD02-2594, MD96-2080) located in the Agulhas leakage area during Termination I and II. Both UK'37 and TEXH86 temperature reconstructions indicate an abrupt warming during the glacial terminations, while a shift to more negative δDalkenone values of approximately 14‰ during glacial Termination I and II is also observed. Approximately half of the isotopic shift can be attributed to the change in global ice volume, while the residual isotopic shift is attributed to changes in salinity, suggesting relatively high salinities at the core sites during glacials, with subsequent freshening during glacial terminations. Approximate estimations suggest that δDalkenone represents a salinity change of ca. 1.7–1.9 during Termination I and Termination II. These estimations are in good agreement with the proposed changes in salinity derived from previously reported combined planktonic Foraminifera δ18O values and Mg/Ca-based temperature reconstructions. Our results confirm that the δD of alkenones is a potentially suitable tool to reconstruct salinity changes independent of planktonic Foraminifera δ18O.
Dissertations / Theses on the topic "Hydrogen termination"
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Ponnuswamy, Thomas Anand. "Hydrogen terminated silicon surfaces: Development of sensors to detect metallic contaminants and stability studies under different environments." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3222/.
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Hydrogen terminated silicon surfaces have been utilized to develop sensors for semiconductor and environmental applications. The interaction of these surfaces with different environments has also been studied in detail. The sensor assembly relevant to the semiconductor industry utilizes a silicon-based sensor to detect trace levels of metallic contaminants in hydrofluoric acid. The sensor performance with respect to two non-contaminating reference electrode systems was evaluated. In the first case, conductive diamond was used as a reference electrode. In the second case, a dual silicon electrode system was used with one of the silicon-based electrodes protected with an anion permeable membrane behaving as the quasi reference electrode. Though both systems could function well as a suitable reference system, the dual silicon electrode design showed greater compatibility for the on-line detection of metallic impurities in HF etching baths. The silicon-based sensor assembly was able to detect parts- per-trillion to parts-per-billion levels of metal ion impurities in HF. The sensor assembly developed for the environmental application makes use of a novel method for the detection of Ni2+using attenuated total reflection (ATR) technique. The nickel infrared sensor was prepared on a silicon ATR crystal uniformly coated by a 1.5 micron Nafion film embedded with dimethylglyoxime (DMG) probe molecules. The detection of Ni2+ was based on the appearance of a unique infrared absorption peak at 1572 cm-1 that corresponds to the C=N stretching mode in the nickel dimethylglyoximate, Ni(DMG)2, complex. The suitable operational pH range for the nickel infrared sensor is between 6-8. The detection limit of the nickel infrared sensor is 1 ppm in the sample solution of pH=8. ATR - FTIR spectroscopy was used to study the changes that the hydride mode underwent when subjected to different environments. The presence of trace amounts of Cu2+ in HF solutions was found to roughen the silicon surface as observed ATR-IR spectroscopy. The initial stages of oxidation in UPW and Cu2+ / UPW was studied. Trace amounts of Cu2+ were found to drastically increase the rate of oxidation, while the rate of oxidation was found to be retarded on removing dissolved oxygen that was present in UPW.
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Luo, Zhi-Zhong, and 羅志忠. "A kinetic study of a major termination reaction in hydrogen/oxygen combustion process." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/55630900293529633276.
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Botas, Alexandre Manuel Pedroso. "Photoluminescence of crystalline silicon nanoparticle systems." Doctoral thesis, 2019. http://hdl.handle.net/10773/27720.
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The understanding of the luminescence properties of silicon at nanoscale is a relevant subject for the development of new light emitting devices.
In this work, the emission features of crystalline silicon nanoparticles is studied. To reveal the role of the surface termination on the photoluminescence properties of silicon nanoparticles with several terminations (hydrogen, silicon oxide or organic molecules) photoluminescence in steady-state and time-resolved modes and measurements of the emission quantum yield were performed. At room temperature, the emission spectra of silicon nanoparticles terminated with hydrogen and functionalized with organic molecules, with average mean diameter of ≈3.4 and ≈2.4 nm present an emission component peaking at ≈800 and ≈750 nm, respectively. This emission component is ascribed to recombination of photogenerated excitons in the silicon core of the nanoparticles. An additional emission component peaking at higher energy, ascribed to the donor-acceptor recombination within states associated with the oxide shell is also present in the spectra of the nanoparticles with an oxide shell. The emission lifetime and quantum yield values depend on the surface termination and are discussed the role of the surface termination int the inter- and intra-nanoparticle exciton transfer. The higher room temperature emission quantum yield was measured for silicon nanoparticles with organic functionalization processed as films (0.23±0.02).
Another aspect studied was the homogeneous infilling of films of silicon nanoparticles with Al2O3 using atomic layer deposition. The infilling allows to protect the films against oxidation and also impacts on the photoluminescence emission spectrum of the nanoparticles. This work opens new questions about the role of the surface termination and separation between nanoparticles on the emission properties.
Taking advantage from the dependence of the nanoparticles emission on temperature, an innovative primary thermometer was developed. It is shown that luminescent thermometers based on silicon nanoparticles films and solutions can operate in distinct environments with the thermometric parameter (emission peak position) described by a well-established equation. The thermometer has a reversibility and repeatability higher than 99.98% and the maximum relative thermal sensitivity is 0.04 %.K−1.O entendimento das propriedades de luminescência do silício à escala nanométrica é uma questão relevante para o desenvolvimento de novos dispositivos emissores de luz. Neste âmbito, esta tese foca o estudo das propriedades de emissão de nanopartículas cristalinas de silício, com diferentes terminações da superfície (hidrogénio, óxido de silício ou moléculas orgânicas), utilizando espectroscopia de fotoluminescência em modo estacionário e resolvido no tempo e medidas de rendimento quântico de emissão. À temperatura ambiente, os espectros de emissão das nanopartículas terminadas com hidrogénio e funcionalizadas com moléculas orgânicas, com tamanhos médios de ≈3.4 e ≈2.4 nm, apresentam uma componente centrada, respetivamente em ≈800 e ≈750 nm. Esta componente é atribuída à recombinação de excitões fotogerados no núcleo de silício da nanopartícula. Uma componente adicional, a maiores energias, está presente no espectro de nanopartículas com óxido de silício à superfície, sendo atribuída à recombinação de pares dados-aceitador de estados associados ao óxido. Os valores medidos para os tempos de vida de emissão e para o rendimento quântico de emissão dependem da terminação da superfície e são discutidos, através da transferência de excitões intra- e inter-nanopartículas. O valor mais alto de rendimento quântico de emissão à temperatura ambiente para amostras em filme foi medido para nanopartículas com funcionalização orgânica (0.23±0.02). Uma outra vertente do trabalho, envolveu filmes de nanopartículas de silício infiltrados com Al2O3, utilizando deposição em camadas atómica. A camada depositada permite proteger os filmes contra a oxidação e observa-se uma alteração do espectro de emissão das nanopartículas, relativamente a nanopartículas análogas sem infiltração. Este trabalho abre novas questões sobre o papel da terminação e separação entre nanopartículas no que respeita às propriedades de emissão. Tirando partido da dependência da emissão com a temperatura foi desenvolvido um termómetro primário inovador. Em particular, é mostrado que termómetros luminescentes baseados em nanopartículas de silício processadas em filme e em solução podem operar em diversos ambientes com um parâmetro termométrico (energia do pico de emissão) descrito por uma equação de estado bem estabelecida. O termómetro apresenta uma reversibilidade e repetibilidade superior a 99.98%, e um valor máximo para a sensibilidade térmica relativa de 0.04 %.K−1.
Programa Doutoral em Física
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Lin, Cheng-Chi, and 林正吉. "Metabolomics Study of hydrogen peroxide induced diapause terminationin brine shrimp." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/y7v5y2.
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碩士國立高雄海洋科技大學
水產養殖研究所
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Brine shrimp is one of the most important feed organisms in aquaculture, it diapause has been extensively studied in embryonic biology for a long time. In the state of dispause, embryo will develop again when they are in suitable environment. we already know use H2O2 with artemia in environmental that hatch rate was increase. Due to entire physiological regulation and environmental factors are still uncertain. This study is based on NMR metabolomics method to find out physiological regulation how H2O2 effects to terminate the diapauses. This experiment were divided into two parts, the first part have three teams with 10 repeat by different concentration, every team access 0.1 g cysts in to ten tube. a, control (0 hr); b, control (5 hrs); c, H2O2 (180 μM) (5 hrs); after 5 days hatching, the second part start with another three sets picked from the rest of cysts spawns ,everyset access 0.1 g cysts into ten tube, A, control; B, H2O2 (180 μM); C, H2O2 (1800 μM). The experiment time was separated in zero and five hours. In first part, the results show that the controls found that arginine and proline metabolism occurred after five hours. Now the cell ware into the cell transcription stage; H2O2 team found valine, leucine and isoleucine biosynthesis, showing the cells have the ability to metabolize. In second part, the results showed that the controls we can found that arginine and proline metabolism; H2O2 (180 μM)group showed alanine, aspartate and glutamate metabolism, glutamate can maintain cell function rining and avtivate MAPK further to effect the gene performances; H2O2 (1800 μM)group showed arginine and proline metabolism. And we found that control and H2O2 (1800 μM)have the similar results obtained in the first part. Those results prove H2O2 could effectively catalysis cell transcription and translation in brine shrimp cells. Furthermore, it improves the speed of cell growth or pushes the cells to grow again.
Book chapters on the topic "Hydrogen termination"
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Izumi, Hiroto. "Hydrogen Termination: The Ideally Finished Silicon Surface." In Ultraclean Surface Processing of Silicon Wafers, 559–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-662-03535-1_43.
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Kumar, Rajesh, Yasuo Kitoh, Koichi Shigematsu, and Kunihiko Hara. "Effect of Surface Termination of Si-Cluster on the Visible Luminescence of Porous-Si: A Correlation with Hydrogen, Fluorine, and Oxygen Atoms." In Control of Semiconductor Interfaces, 417–22. Elsevier, 1994. http://dx.doi.org/10.1016/b978-0-444-81889-8.50077-8.
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Fawcett, W. Ronald. "Liquids and Solutions at Interfaces." In Liquids, Solutions, and Interfaces. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195094329.003.0012.
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When the properties of liquids and solutions are considered, attention is normally focused on the bulk of the phase, and the properties of the system at its boundaries are ignored. Significant effects are associated with the region near the surface of a liquid phase and an understanding of these is an important part of solution chemistry. As a simple example, consider a beaker of pure water at room temperature in a closed inert environment. As has been seen in the consideration of liquid structure, the properties of water are strongly influenced by hydrogen bonding between neighboring molecules, and to a lesser extent by dipole–dipole interactions. As an observer at the molecular level, one would find that the molecules near the boundaries of the water phase have different properties. There are two boundaries in this system, the water | air interface and the water | glass interface. At the water | air interface, the important feature is the termination of intermolecular interactions, so that molecules must adjust to an environment where the number of nearest neighbors is reduced. At the water | glass interface, water molecules meet the components of glass, a supercooled liquid with silicon dioxide as the major component. Interaction between water and silicon dioxide is different from interaction among water molecules. It is clear that the molecular environment at these interfaces is very different than it is in the bulk. As a result, local properties are different. Now imagine that the water in the beaker is dispersed as a fog, that is to say, as many very small droplets for which the ratio of surface area to volume is much larger than for the water in the beaker. It is obvious that the thermodynamic properties of the fog, a colloidal system, are very different from those of the water as a macrosystem in a beaker. In order to create the fog considerable work must be done to form a system with a much larger surface area. This means that the Gibbs energy of a fog containing the same number of water molecules as the beaker of water is much higher.
Conference papers on the topic "Hydrogen termination"
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Kubo, Momoji, Yumiko Sasaki, Keiko Chiba, Pei Qiang, Abdul Rajjak, Hideyuki Tsuboi, Michihisa Koyama, et al. "Large-Scale Quantum Chemical Molecular Dynamics Simulations on the Formation Dynamics of Hydrogen by the Chemical Reactions of Water." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72132.
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We have successfully simulated the chemical reaction dynamics of water molecules on various Si surfaces by using our new tight-binding quantum chemical molecular dynamics method. The formation dynamics of hydrogen molecules from water molecules on Si nano-particle was observed at 300 K. Especially, we found that the surface termination of Si nano-particle strongly influences the chemical reactions of water molecules and the non-terminated Si surface is the active site for the hydrogen generation. Moreover, we suggest that nano-space of the SiO2/Si interface is more active site for the hydrogen generation.
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Kawaguchi, Munemichi, Shinya Miyahara, and Masayoshi Uno. "Discussion About Sodium-Concrete Reaction in Presence of Internal Heater." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-82233.
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Sodium-concrete reaction (SCR) is one of the important phenomena during severe accidents in sodium-cooled fast reactors (SFRs) owing to the generation of large sources of hydrogen and aerosols in the containment vessel [1–3]. In this study, SCR experiments were performed to investigate the chemical reaction beneath the internal heater (800 °C), which was used to simulate the obstacle and heating effect for SCR. Furthermore, the effects of the internal heater on the self-termination mechanism were discussed. The internal heater on the concrete seemed to hinder the transport of Na into the concrete. Therefore, Na could react with the concrete at the periphery of the internal heater. The concrete ablation depth at the periphery was larger than under the internal heater. However, the Na concentration around the reaction front was about 30 wt.% despite the position of the internal heater. The Na concentration was similar to that of Na2SiO3, which was almost same as that in our past study [4–5]. It was found that the Na concentration condition was one of the dominant parameters for the self-termination of SCR, even in the presence of the internal heater.
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Eryilmaz, O. L., and A. Erdemir. "Effect of Tribochemical Interactions on Friction and Wear of Highly Hydrogenated DLC Films." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44412.
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In this paper, we attempted to elucidate the nature and extent of tribochemical interactions between sliding surfaces of highly-hydrogenated diamondlike carbon (DLC) films (containing about 40 at.% hydrogen) and correlated these findings with their friction and wear behaviors in dry and humid nitrogen environments. For the tribochemical studies, we used a time-of-flight secondary ion mass spectrometer (ToF-SIMS) in 2- and 3-D imaging modes, while for tribological tests, we used a ball-on-disk machine that was operated under a 5 N load and at sliding velocities of 0.2 to 0.3 m/s. In dry nitrogen, the DLC films provided a friction coefficient of ≈ 0.007, but in humid nitrogen, the friction coefficient 3 to 4 times higher. 3-D surface profilometry and optical microscopy did not reveal much wear on sliding ball and disk surfaces after the tests regardless of the test environment, but the 2- and 3-D ToF-SIMS images of the same surfaces revealed very rich tribochemistry for films tested in humid nitrogen but not much chemistry for those films tested in dry nitrogen. Complementary x-ray photoelectron spectroscopy of these sliding surfaces showed similar results further confirming extensive tribo-oxidation (in the forms of both C-O and C=O) of DLC surfaces tested in humid nitrogen but no major chemical changes in DLC films tested in dry nitrogen. Based on the results of surface analytical and tribological studies, we concluded that superlow friction behavior of highly hydrogenated DLC films was perhaps due to the hydrogen termination of their surface carbon atoms, while the much higher friction coefficients observed in humid nitrogen was primarily due to tribo-oxidation and/or oxygen termination of these surfaces.
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Kalitan, Danielle M., Eric L. Petersen, John D. Mertens, and Mark W. Crofton. "Ignition of Lean CO/H2/Air Mixtures at Elevated Pressures." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90488.
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Shock-tube ignition delay time experiments and chemical kinetics model calculations were performed for several fuel blends of carbon monoxide and hydrogen in air at elevated pressures. Due to the interest in coal-derived fuels, namely syngas, these data are important for characterizing the ignition and oxidation of possible fuel blends used in gas turbines and for the validation of chemical kinetics models. Three lean, CO/H2 (80/20%, 90/10%, and 95/5% by volume) fuel blends in air were studied behind reflected shock waves at temperatures between 929 and 1304 K and pressures ranging from 1.7 to 15 atm. Ignition delay times were monitored using chemiluminescence emission from excited hydroxyl radicals. Results exhibit the second-explosion limit behavior from hydrogen oxidation kinetics at low temperatures and high pressures for all mixtures. In addition, comparisons of modeling results and experimental data show good agreement for the entire temperature range at high pressure and poor agreement with the data at low temperatures in the intermediate pressure regimes. Ignition and reaction sensitivity analyses indicate that the H + O2 + M = HO2 + M termination reaction is important at all conditions herein, and the early formation of HO2 suppresses the growth of the ignition-enhancing radicals H and OH.
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Robinson, Vance S., T. S. Fisher, Yoshiyuki Show, Greg Swain, and Frank Pfeferkon. "Thermionic Emission Energy Distributions From Nanocrystalline Diamond." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59406.
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Thermionic electron emission provides a means of direct energy conversion. Some of the benefits of thermionic power generation include: compactness, scalability, stability, lack of moving parts, and applicability to microscale devices. Taking advantage of these benefits requires the analysis and subsequent manufacturing of materials that emit electrons efficiently and at reasonable temperatures (<1000 °C). We report here on a study being performed to characterize the emission properties of such materials, namely, nanocrystalline diamond with hydrogen and oxygen termination. A hemispherical energy analyzer is used to measure the electron energy distribution from this nanostructured material at elevated temperatures. The effective work function and the presence of regions of differing work functions are determined. Measurements of thermionic emission energy distributions (TEEDs) at temperatures ranging from 573 to 778 °C are presented. The TEEDs show an intriguing development of multiple peaks at higher temperatures, possibly indicating instability in the emitter’s surface chemistry.
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Evin, Harold N., Jerome Peultier, Gilles Thevenet, Olivier Wagner, Henri Romazzotti, and Jean-Philippe Roques. "Hydrogen Induced Corrosion Cracking and Crevice Corrosion Behavior in Natural Sea Water of Super Duplex Seam Welded Tubes for Umbilicals Applications." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41755.
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Umbilicals are important tubes assembly essentially used for subsea equipment controlling functions and fluid injection. Super duplex stainless steel 2507 (UNS 32750 / EN 1.4410) has been the historical grade used for its corrosion resistance and mechanical properties. The Oil and Gas industry is gradually working on the exploration and exploitation of offshore and deep offshore resources. These operating conditions lead to new philosophy in the design of subsea umbilicals, which are evolving to answer the needs of new functionalities. Recent years development supported by O&G operators, have seen innovative super duplex stainless seam welded tube solution being used for their high mechanical characteristics (YS0.2≥ 750 MPa; UTS≥ 900 MPa), tight dimension tolerances, and their ability to generate cost saving during installation. The specific metallurgical manufacturing route for the 2507 strip together with an efficient roll forming process and NDT control allows to obtained tubes for umbilicals which push the usual boundaries of utilization of this super duplex grades. In this paper, Hydrogen Induced Stress Cracking (HISC) behavior, possible failure mode of the super duplex stainless steel tubes exposed to cathodic protection in the termination unit, was extensively studied. A stress load of 110% YS0.2 was applied using a dead weight bench and the tubes performance was characterized after 500h of exposure in synthetic sea water under cathodic protection. Crevice corrosion is also a reported failure mode for umbilical tubes. Corrosion resistance of the 2507 seam welded tubes was also assessed in natural sea water in crevice conditions at open circuit potential (OCP). No failure was observed during the HISC testing in synthetic sea water after 500hours of exposure and no micro-crack was detected on the tubes after characterization. The metallurgical microstructure of the laser weld is not preferential initiation zone for crevice corrosion.
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Wang, Te-Chuan. "Comparison of Severe Accident Results by Using MAAP5 and MAAP4 Codes." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29017.
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MAAP5 (Modular Accident Analysis Program Rev. 5.0.0), developed by Fauske & Associates, Inc.’s (FAI) based on the MAAP4 code, is a severe accident analysis code. It is a computer program capable of simulating the response and mitigation actions of light water reactor nuclear power plants (NPPs), including advanced boiling water reactor (ABWR) during severe accident. A specific loss of all core cooling accident sequence, LCLP-PF-R-N, based on Final Safety Analysis Report (FSAR) of Lungmen (ABWR) NPP, was selected as a based case and simulated by the MAAP5 and MAAP4 codes. The MAAP5 and MAAP4 parameter files for Lungmen NPP were established based on Lungmen NPP design data and the MAAP5 and MAAP4 users’ guides. The main severe accident phenomena and the fission product release fractions associated with the LCLP-PF-R-N sequence were simulated. The purpose of this paper is to compare the analysis results of LCLP-PF-R-N sequence calculated by MAAP5 and MAAP4 codes. The two codes give similar results for important phenomena during the accidents, including core uncovery, core support plate failure, debris relocation to the lower plenum, vessel failure, passive flooder opens, containment overpressure protection system (COPS) activation, noble gases and volatile species (like CsI) release to environment, except for the amount of hydrogen production in core. MAAP5 predicts a greater amount of hydrogen production in core than that of MAAP4. This is because MAAP4 predicts earlier reactor pressure vessel (RPV) depressurization than that of MAAP5. That results in earlier steam exhaustion and oxidation reaction termination in core than those of MAAP5. This paper successfully demonstrates the severe accident of Lungmen NPP, and analysis results can provide useful information for the MAAP5 and MAAP4 users.
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Murashima, Motoyuki, Yusuke Imaizumi, Takazumi Yamada, Katsuno Shotaro, Tomoki Yoshida, Noritsugu Umehara, and Takayuki Tokoroyama. "Low Friction Realised by Hydrogen-Ended DLC Surface Through Photocatalyst Effect in Water Lubricated Condition." In JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/lemp2020-8537.
Full textAbstract:
Abstract This study shows a new friction reduction method for a diamond-like carbon (DLC) coating using photocatalyst in water lubricated condition. It is well known that one of DLC coatings (e.g. hydrogenated amorphous carbon, a-C:H) exhibits low friction due to repulsive force generated by hydrogens on their top most surfaces. Thus, the low friction is mainly occurred in inert gas environment. On the other hand, if we can produce hydrogenated surface positively, low friction may be achieved in lubricated conditions. Here, it is well known that water electrolysis by photocatalyst generates hydrogen and oxygen atoms/molecules. In this research, we propose a new hydrogen terminating method for DLC surfaces with hydrogens generated by water electrolysis. Moreover, we clarified the effect of the hydrogen-end on lowering friction. We conducted friction tests using an a-C:H coating against a TiO2 disk (photocatalyst) in water lubricated condition. The friction test result showed a decrease in the friction coefficient which was associated with UV irradiation. It is considered that the reduction in hydrogen-bonding component of surface energy indicates a highly hydrogen-ended surface creation, resulting in higher repulsive force and lower friction.
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Popat, Ajay M., and Chad B. O’Neal. "Process Optimization for Releasing of MEMS/NEMS Devices and Coating of Anti-Stiction SAM." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43820.
Full textAbstract:
Micro electromechanical systems (MEMS) or nano electromechanical systems (NEMS) have higher surface-to-volume ratio, and hence they are susceptible to unintentional adhesion and subsequent failure to function. Although there are many classes of liquid phase anti-stiction coatings for silicon MEMS / NEMS, alkene based monolayer films with hydrogen terminated silicon coatings were chosen since this process has some important advantages over other SAM processes, such as fluorine or chlorine based films. An engineering challenge of scaling up liquid-phase anti-stiction and release processes is met by designing and fabricating a semi-automated and portable MEMS release station, which enables 20 – 40 dice or a wafer up to 100 mm in diameter to be released and coated at one time. This optimized release and coating process reduces processing time and chemical processing volume drastically compared to releasing and coating dice individually. The simultaneous processing of multiple dice was enabled through an inert FEP - Teflon dice-holder-clamp. The clamp is adaptable to hold varied sizes of dice with no lost die. The successful elimination of the secondary HF rinse for hydrogen termination has resulted in additional saving of expensive HF, additional saving of process time, and reduced exposure to the dangerous chemical - HF. The increase in hydrophobicity resulted from the optimized release and SAM coating process was confirmed through the average increase, from 68.2° to 109.3°, in water contact angle of SAM coated Si (100). The increase in the average surface roughness from 0.4 nm for source procedure to ∼ 4 nm using optimized release and SAM coating process became evident through the AFM scanned images. The increase in hydrophobicity and surface roughness using the optimized release and SAM coating process play vital roles in preventing the stiction of MEMS / NEMS devices. This scalable process has good yield and is easier to use and train personnel than a typical SAM coating process.
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Naitoh, Masanori, Marco Pellegrini, Hiroaki Suzuki, Hideo Mizouchi, and Hidetoshi Okada. "Analysis of Accident Progression of Fukushima Daiichi NPP by the SAMPSON Code." In 2014 22nd International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icone22-30607.
Full textAbstract:
This paper describes analysis results of the early phase accident progression of the Fukushima Daiichi Nuclear Power Plant (NPP) Unit 1 by the severe accident analysis code SAMPSON. The isolation condensers were the only devices for decay heat removal at Unit 1, but they stopped after the loss of AC and DC powers. Since there were no decay heat removal for about 14 hours after their termination until the start of alternative water injection into the core by the fire engine, the core melt and the reactor pressure vessel (RPV) bottom failure occurred resulting in large amount of fission products release into the environment. The original SAMPSON was improved by adding new modellings for the phenomena which have been deemed specific to the Fukushima Daiichi NPP: (1) deterioration of SRV gaskets and (2) buckling of in-core-monitor housings which caused the early steam leakage from the core into the drywell, and (3) melt of the in-core-monitor housings in the lower plenum of the RPV. The analysis results showed that (1) 55.3% of UO2 of the initial loading and 66.1% of the core material including UO2, zircaloy, steel and control materials had melted down into the pedestal of the drywell, (2) the amount of Hydrogen generated by Zr-H2O reaction was 686 kg, (3) amount of Cs element released from fuels was 61 kg which was 72% of the total Cs element which was included in fuels at the initiation of the accident, and (4) 18.3% of the corium which fell into the pedestal was one large lump and the 81.7% was particulate corium.