The Experts below are selected from a list of 56913 Experts worldwide ranked by ideXlab platform
Pierre Fauchais - One of the best experts on this subject based on the ideXlab platform.
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synthesis of ultra fine particles by plasma transferred arc influence of anode material on particle properties
Journal of The European Ceramic Society, 2006Co-Authors: C Chazelas, J F Coudert, J Jarrige, Pierre FauchaisAbstract:Abstract There is a great deal of interest today in the special properties of nanoparticles and their potential applications. Gas-phase process, although having some drawbacks, has the largest control possibilities and is therefore the method chosen here. The size of the primary particles depends on the temperature/time history and material properties. Further growth of the particles strongly depends on the properties of the flow into which they are imbedded. In the current work, a transferred arc is used to produce nanometric particles from the condensation of metallic vapours obtained by Controlled evaporation of the anode material, which becomes the solid precursor of the synthesis. As all types of anode materials would be used, depending of the nature of the desired particles, this technique requires a good control of the heat transfer and its application time to a given anode location, as well as the separation of evaporation/ nucleation-growth steps. That is why a new and original experimental set-up was built in order to control vapour production and its thermal history. Experiments showed that the heat transfer at the anode precursor strongly depends on the cold boundary layer (CBL) properties close to the anode. For adequate parameters, it becomes possible to generate either diffuse or constricted stable arc root, and so to control vapour production. Orientation and so dissociation of evaporation and nucleation events is also achieved by tilting the angle between the jet issued from the cathode and the anode. The vapours produced are then naturally entrained towards a temperature Controlled Zone, where they are collected onto a water cooled substrate. It thus becomes possible to control the residence time and the thermal vapour history of the particles. Whereas aluminium oxide particles synthesized are clearly nanoparticle chain aggregates, iron oxides particles are spherical, in the micrometric range and no aggregates or agglomerates are visible. These experiments show that particle morphology, size and shape, for given working parameters, strongly depend on the properties of the material to be vaporized.
John R Engen - One of the best experts on this subject based on the ideXlab platform.
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subzero celsius separations in three Zone temperature Controlled hydrogen deuterium exchange mass spectrometry
Journal of Chromatography A, 2017Co-Authors: Thomas E Wales, Keith Fadgen, Michael J Eggertson, John R EngenAbstract:Hydrogen deuterium exchange mass spectrometry (HDX MS) reports on the conformational landscape of proteins by monitoring the exchange between backbone amide hydrogen atoms and deuterium in the solvent. To maintain the label for analysis, quench conditions of low temperature and pH are required during the chromatography step performed after protease digestion but before mass spectrometry. Separation at 0°C is often chosen as this is the temperature where the most deuterium can be recovered without freezing of the typical water and acetonitrile mobile phases. Several recent reports of separations at subzero Celsius emphasize the promise for retaining more deuterium and using a much longer chromatographic gradient or direct infusion time. Here we present the construction and validation of a modified Waters nanoACQUITY HDX manager with a third temperature-Controlled Zone for peptide separations at subzero temperatures. A new Peltier-cooled door replaces the door of a traditional main cooling chamber and the separations and trapping column are routed through the door housing. To prevent freezing, 35% methanol is introduced post online digestion. No new pumps are required and online digestion is performed as in the past. Subzero separations, using conventional HPLC column geometry of 3μ m particles in a 1×50mm column, did not result in major changes to chromatographic efficiency when lowering the temperature from 0 to -20°C. There were significant increases in deuterium recovery for both model peptides and biologically relevant protein systems. Given the higher levels of deuterium recovery, expanded gradient programs can be used to allow for higher chromatographic peak capacity and therefore the analysis of larger and more complex proteins and systems.
T C Pharaoh - One of the best experts on this subject based on the ideXlab platform.
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the elbe fault system in north central europe a basement Controlled Zone of crustal weakness
Tectonophysics, 2002Co-Authors: M Scheck, Ulf Bayer, Volker Otto, Juliette Lamarche, D Banka, T C PharaohAbstract:Abstract The Elbe Fault System (EFS) is a WNW-striking Zone extending from the southeastern North Sea to southwestern Poland along the present southern margin of the North German Basin and the northern margin of the Sudetes Mountains. Although details are still under debate, geological and geophysical data reveal that upper crustal deformation along the Elbe Fault System has taken place repeatedly since Late Carboniferous times with changing kinematic activity in response to variation in the stress regime. In Late Carboniferous to early Permian times, the Elbe Fault System was part of a post-Variscan wrench fault system and acted as the southern boundary fault during the formation of the Permian Basins along the Trans-European Suture Zone (sensu [Geol. Mag. 134 (5) (1997) 585]). The Teisseyre–Tornquist Zone (TTZ) most probably provided the northern counterpart in a pull-apart scenario at that time. Further strain localisation took place during late Mesozoic transtension, when local shear within the Elbe Fault System caused subsidence and basin formation along and parallel to the fault system. The most intense deformation took place along the system during late Cretaceous–early Cenozoic time, when the Elbe Fault System responded to regional compression with up to 4 km of uplift and formation of internal flexural highs. Compressional deformation continued during early Cenozoic time and actually may be ongoing. The upper crust of the Elbe Fault System, which itself reacted in a more or less ductile fashion, is underlain by a lower crust characterised by low P-wave velocities, low densities and a weak rheology. Structural, seismic and gravimetric data as well as rheology models support the assumption that a weak, stress-sensitive Zone in the lower crust is the reason for the high mobility of the area and repeated strain localisation along the Elbe Fault System.
Kangning Li - One of the best experts on this subject based on the ideXlab platform.
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heat transfer enhancement through control of added perturbation velocity in flow field
Energy Conversion and Management, 2013Co-Authors: Jiansheng Wang, Cui Wu, Kangning LiAbstract:Abstract The characteristics of heat transfer and flow, through an added perturbation velocity, in a rectangle channel, are investigated by Large Eddy Simulation (LES). The downstream, vertical, and upstream control strategy, which can suppress the lift of low speed streaks in the process of improving the performance of heat transfer, are adopted in numerical investigation. Taking both heat transfer and flow properties into consideration, the synthesis performance of heat transfer and flow of three control strategies are evaluated. The numerical results show that the flow structure in boundary layer has been varied obviously for the effect of perturbation velocity and induced quasi-streamwise vortices emerging around the Controlled Zone. The results indicate that the vertical control strategy has the best synthesis performance of the three control strategies, which also has the least skin frication coefficient. The upstream and downstream strategies can improve the heat transfer performance, but the skin frication coefficient is higher than that with vertical control strategy.
C Chazelas - One of the best experts on this subject based on the ideXlab platform.
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synthesis of ultra fine particles by plasma transferred arc influence of anode material on particle properties
Journal of The European Ceramic Society, 2006Co-Authors: C Chazelas, J F Coudert, J Jarrige, Pierre FauchaisAbstract:Abstract There is a great deal of interest today in the special properties of nanoparticles and their potential applications. Gas-phase process, although having some drawbacks, has the largest control possibilities and is therefore the method chosen here. The size of the primary particles depends on the temperature/time history and material properties. Further growth of the particles strongly depends on the properties of the flow into which they are imbedded. In the current work, a transferred arc is used to produce nanometric particles from the condensation of metallic vapours obtained by Controlled evaporation of the anode material, which becomes the solid precursor of the synthesis. As all types of anode materials would be used, depending of the nature of the desired particles, this technique requires a good control of the heat transfer and its application time to a given anode location, as well as the separation of evaporation/ nucleation-growth steps. That is why a new and original experimental set-up was built in order to control vapour production and its thermal history. Experiments showed that the heat transfer at the anode precursor strongly depends on the cold boundary layer (CBL) properties close to the anode. For adequate parameters, it becomes possible to generate either diffuse or constricted stable arc root, and so to control vapour production. Orientation and so dissociation of evaporation and nucleation events is also achieved by tilting the angle between the jet issued from the cathode and the anode. The vapours produced are then naturally entrained towards a temperature Controlled Zone, where they are collected onto a water cooled substrate. It thus becomes possible to control the residence time and the thermal vapour history of the particles. Whereas aluminium oxide particles synthesized are clearly nanoparticle chain aggregates, iron oxides particles are spherical, in the micrometric range and no aggregates or agglomerates are visible. These experiments show that particle morphology, size and shape, for given working parameters, strongly depend on the properties of the material to be vaporized.