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Deposition Mechanisms (deposition + mechanism)
Selected AbstractsDeposition Mechanism for Chemical Vapor Deposition of Zirconium Carbide CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2008Yiguang Wang Zirconium carbide (ZrC) coatings were fabricated by chemical vapor deposition (CVD) using ZrCl4, CH4/C3H6, and H2 as precursors. Both thermodynamic calculation results and the film compositions at different temperatures indicated that zirconium and carbon deposited separately during the CVD process. The ZrC deposition rates were measured for CH4 or C3H6 as carbon sources at different temperatures based on coating thickness. The activation energies for ZrC deposition demonstrated that the CVD ZrC process is controlled by the carbon deposition. This is also proven by the morphologies of ZrC coatings. [source] Electrochemical Detection of Trace Concentrations of Cadmium and Lead with a Boron-Doped Diamond Electrode: Effect of KCl and KNO3 Electrolytes, Interferences and Measurement in River WaterELECTROANALYSIS, Issue 3 2004Carol Babyak Abstract Parts-per-billion levels of cadmium and lead were detected using square-wave anodic stripping voltammetry with a boron-doped diamond electrode. Calibration plots (10-minute deposition time) in KCl and KNO3 were non-linear at low concentrations (1,5,ppb) due to the deposition mechanism of these metals. The preferred electrolyte for cadmium was KCl, while lead could be measured in either electrolyte. The lowest concentrations included in the linear portion of the calibration plot (5,minute deposition time) for cadmium were 10,ppb and 50,ppb in KCl and KNO3, respectively, and 10,ppb for lead in KNO3. The presence of either lead or copper suppressed the cadmium stripping peak, but the lead stripping peak was unaffected by cadmium, and enhanced by the addition of copper. A river water sample was analyzed for cadmium and lead, and the cadmium results were confirmed using ICP-AES spectrometry. It was determined electrochemically that a fraction of lead in the river sample was bound by complexing material in the sample. [source] Predicting HCl concentrations in fire enclosures using an HCl decay model coupled to a CFD-based fire field modelFIRE AND MATERIALS, Issue 7 2007Z. Wang Abstract The amount of atmospheric hydrogen chloride (HCl) within fire enclosures produced from the combustion of chloride-based materials tends to decay as the fire effluent is transported through the enclosure due to mixing with fresh air and absorption by solids. This paper describes an HCl decay model, typically used in zone models, which has been modified and applied to a computational fluid dynamics (CFD)-based fire field model. While the modified model still makes use of some empirical formulations to represent the deposition mechanisms, these have been reduced from the original three to two through the use of the CFD framework. Furthermore, the effect of HCl flow to the wall surfaces on the time to reach equilibrium between HCl in the boundary layer and on wall surfaces is addressed by the modified model. Simulation results using the modified HCl decay model are compared with data from three experiments. The model is found to be able to reproduce the experimental trends and the predicted HCl levels are in good agreement with measured values. Copyright © 2006 John Wiley & Sons, Ltd. [source] Measuring hydrate/ice deposition in a flow loop from dissolved water in live liquid condensateAICHE JOURNAL, Issue 7 2009Joseph W. Nicholas Abstract Experiments were conducted to investigate hydrate/ice plugging and deposition mechanisms from water dissolved in a liquid condensate system, using a single-pass flow loop. Two different hydrate/ice plugging mechanisms were observed. Hydrate/ice deposition from a dissolved-water phase resulted in a lengthwise uniform/dispersed deposit and a gradual pressure drop increase. The dispersed deposit acted as insulation at the flow loop wall, and the deposit began to propagate downstream. However, cooling below the liquid-water saturation curve resulted in free water coalescence, and a localized hydrate/ice restriction in the flow loop. This localized restriction resulted in a rapid pressure drop increase. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Correlation equation for predicting filter coefficient under unfavorable deposition conditionsAICHE JOURNAL, Issue 5 2008You-Im Chang Abstract A new correlation equation for predicting the filter coefficient under unfavorable deposition conditions is presented. By adopting the triangular network model of using the Brownian dynamic simulation method, as the sum of four individual deposition mechanisms, e.g., the Brownian diffusion, the DLVO interactions, the gravitational force, and the interception, the correlation equation is obtained by regressing against a broad range of parameter values governing particle deposition in deep bed filtration. The new correlation equation is able to describe previous experimental results well, especially for those submicro particles with significant Brownian motion behavior. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Seasonal and reproductive variation in body condition in captive female Japanese macaques (Macaca fuscata)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2010Cécile Garcia Abstract The geographic distribution of Japanese macaques includes populations with the most northern range of any primate species. Not surprisingly, females of this species are characterized by physiological adaptations and unique fat deposition mechanisms that facilitate their survival through the sometimes-harsh seasonal conditions of temperate climates, as well as sustaining the metabolic costs of mating, pregnancy, and lactation. Here, we explore the relationship between nutritional status, seasonality, and reproductive status using anthropometric and leptin measures from 14 captive female Japanese macaques. No seasonal patterns were found in the levels of leptin, but there were differences between seasons in anthropometric measures, specifically between the beginning and the end of the mating season. Females gained weight and accumulated energy reserves in fall to prepare for mating activity, and to survive the severe conditions of winter, which is also the period of gestation if pregnancy occurs. Lactating females had larger total skinfolds relative to nonlactating individuals, and females with older babies at the beginning of the mating season had larger abdominal skinfolds than did those with younger babies. There was a relationship between the likelihood of conception and nutritional status, with females that conceived during one mating season being in better condition at the end of their previous mating season. Together, these results suggest that, even in captive settings, seasonal breeding has a cost on the energetic demands of mating, and that higher condition (i.e. fatter) females could afford the demands of lactation and reproduced more rapidly. Am. J. Primatol. 72:277,286, 2010. © 2009 Wiley-Liss, Inc. [source] | ||||||||||