This research focuses on electrothermal vaporization (ETV) as a sample introduction source for inductively coupled plasma mass spectrometry (ICPMS). ETV creates a dry plasma that causes problems when used at the high applied powers (e.g., 1.2 kW) typically employed for nebulizer-based sample introduction for certain ICPMS instruments. A secondary discharge forms in the sampling region of the spectrometer, but this effect was removed by reducing the applied power (e.g., 0.7 kW). A novel, steady state, dry aerosol introduction system was developed to permit optimization of the ICPMS settings. The device used solid NbF₅, SnBr₄ and a W filament plated with Pb to generate dry aerosols which produced ²⁸Si⁺, ⁷⁹Br⁺, ¹²⁰Sn⁺, ¹⁸⁴W⁺, and ²⁰⁸Pb⁺ that were used to optimize the ICPMS. When compared to an ICPMS optimized using a nebulizer, the dry optimized plasma produced an average enhancement of 4.5(±0.4) for 26 elements when using ETV sample introduction. The ETV produces a short (0.5-2 s) transient pulse once every 2-3 min, resulting in a sample throughput of 20-30 samples/h. To increase this throughput, a low power, low background multiplexed ETV device using carbon braids as vaporizers was developed. Oxygen ashing was demonstrated with recoveries of 96±17% for a suite of elements. Refractory elements (e.g., V and U) showed precision of greater than 25% while medium to high volatility elements were in the 10-20% range. The lifetime of the braids was limited to ca. 30 vaporizations when heated to 2,800°C. A device for coupling an ETV in parallel with a nebulizer was also designed and characterized. The device was designed to minimize the impact of the ETV's presence on nebulizer-based ICPMS performance. The ETV could be easily switched on line to provide complimentary information that may be unavailable with nebulizer sample introduction because of isobaric interference problems. For example, in a 1% HCl matrix, the detection limits for ⁵¹V⁺ (⁵¹ClO⁺ interference), ⁷⁵As⁺ (⁷⁵ArO⁺ interference) and ⁷⁸Se⁺ were found to be 0.008 ppb, 0.088 ppb, 0.063 ppb, respectively. By contrast, the nebulizer detection limits in 1% HCl for ⁵¹V⁺, ⁷⁵As and ⁷⁸Se were found to be 0.593 ppb 1.488 ppb and 1.158 ppb, respectively. / text

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Acoustic droplet vaporization (ADV) is a process in which a phase shift of a liquified droplet into a gaseous microbubble, is triggered using an ultrasonic wave. In contrast to utilizing conventional contrast agents in ultrasound, the phase change contrast agents used in ADV can extravasate into tumor tissue, and they offer a greater circulatory lifespan, thereby increasing the potential applications in which they can be utilized. In this project, the impact of different ultrasound parameters on the efficiency of ADV was investigated, using a programmable ultrasound system. Two different ultrasound sequences were designed, for imaging and vaporization of droplets. Furthermore, three different sets of experiments were performed. Firstly, the vaporization effect of different imaging voltages was investigated, whereby a setting of 15V was identified as an able voltage for the remaining experiments. Secondly, experiments concerning the effect of vaporizing frequency on the ADV efficiency were performed, including the use of single and dual frequencies. Lastly, different frequency settings were combined with varying the number of cycles, to assess how the choice of pulse length influences the vaporization. The results from the project indicate that no substantial difference in ADV efficiency is achieved when using different frequency settings for perfluoropentane droplets encapsulated by cellulose nanofibers. However, the results provide clear indications of the benefit of using longer pulse durations on the vaporization efficiency. In conclusion, further studies are required before ADV can be translated into a clinical setting.

No description available.

The research focuses on the fate of heavy metals and their emissions from pulp mill recovery boilers. Heavy metals are extremely toxic and cause adverse effects on human health. There is limited information about factors affecting heavy metal vaporization from recovery boilers, in which spent pulping liquors, (also called black liquor) is burnt. The heavy metals are present in trace quantities in black liquor. They are emitted in the air as submicron particles, and their amount of emission depends on the input of metals into the recovery boiler, volatilization of metals in the boiler and the efficiency of the electrostatic precipitator (ESP) to remove the metals. The heavy metals vaporization from different recovery boilers vary widely and the reason is not known. My thesis will focus on determining what conditions affect the volatility of the heavy metals, and whether differences in heavy metal vaporization are due to differences in boiler operating conditions or the composition of the liquor. I will examine black liquor pyrolysis, combustion and gasification in well-controlled laboratory conditions. I will analyze three different black liquors. The liquors will be spray-dried and burnt or gasified in a laminar entrained-flow reactor at high temperatures of 1000-1100C and residence times ranging from 0.5 to 1.5 s. Equilibrium calculations will be performed to determine the distribution of heavy metals and species under set conditions from previous devolatilization experiments. The equilibrium calculations will serve as a useful tool for prior estimation of the distribution of heavy metals. The impact of different liquors on volatilization of heavy metals in the experiments will be determined. The char residue and condensation aerosol (fume) particles from each experiment will be analyzed using ICP-AES. The amount of heavy metals volatilization during combustion and gasification will be determined based on the amount of the metals in the char residues and fume particles. Based on the results of the experimental study combined with data from the equilibrium analysis program the main cause of variability in heavy metal vaporization can be found. Also the boiler operating conditions can be studied to determine its affects on the volatility of the heavy metals.

The history of planet formation and evolution is strongly tied to understanding the outcomes of a wide range of impact events, from slow accretionary events to hypervelocity events that melt and vaporize large fractions of the colliding bodies. To better understand impact processes, their effects on planetary evolution, and how to interpret geochemical data, we need to improve our knowledge of the behavior of materials over the entire range of conditions accessed by collisions. Here I present experimental results from gas gun, laser driven, and pulsed power facilities. Together these facilities can access the tremendously wide range of pressure and temperature conditions achieved in natural impact events. This work focuses on the thermodynamics of impacts to better understand the phase transitions that most strongly affect the dynamics and chemical consequences of a collision. I show that the entropy generation during collisions is the most natural means of interpreting the thermodynamic processes that occur during an impact event. For materials with sufficient thermodynamic data at high pressures and temperatures, I present a method for obtaining the entropy generation during an impact. With the knowledge of the entropy, I present new shock-and-release techniques to investigate the liquid-vapor region of the phase diagram. I also show that for materials without sufficient data to calculate the entropy generation during an impact, one can use the shock-and-release techniques described here to determine the entropy in the high pressure shock state. With better equation of state models that are constrained by our experimental data, our confidence in impact models improves dramatically. Using a high fidelity equation of state for \(H_2O\). ice, I derive scaling laws for how much \(H_2O\) ice melts and vaporizes for impacts onto icy bodies. Recognizing that icy bodies are not pure ice, I have performed experiments to show how the impact energy partitions between the disparate phases. Finally, I discuss some of the uncertainties in using the laboratory experiments to directly interpret the effects of impacts in nature. / Earth and Planetary Sciences

Droplet vaporization and combustion of biodiesel, diesel and their blends was examined experimentally in a turbulent flow at elevated ambient temperature and pressure conditions. A high pressure vessel capable of generating high levels of turbulence was employed in this study. The linear relationship between turbulence intensity and fans rotational speed, which was developed at room temperature, was found to be unaffected by the gas ambient temperature. Droplet vaporization experiments were performed by varying turbulence intensity (i.e., the fans rotational speed) from 0 up to 3.1 m/s, ambient temperature and pressure up to 473 K and 16 bar, respectively. The results revealed that diesel droplet vaporization did not follow the d2-law under the aforementioned test conditions. However, biodiesel droplet vaporization obeyed the d2-law. Droplet vaporization of the blends, i.e. B20 and B50, displayed a mixed behaviour of both parent fuels with the biodiesel behaviour predominating where biodiesel content slows down the droplet vaporization of the blends. Turbulence was found to reduce the droplet lifetime of all fuels (i.e., increases droplet vaporization rate), and its effect becomes more effective with increasing ambient pressure. Droplet combustion experiments were performed by varying turbulence intensity from 0 up to 1.20 m/s, and ambient temperature up to 423K at ambient pressure of 1 atm. Diesel droplet combustion rate showed negligible change with turbulence intensity up to 0.40 m/s beyond which the burning rate decreased slightly with turbulence intensity. Similarly, biodiesel droplet combustion rate did not show an increase with the presence of a turbulent flow around the droplet. However, in contrast to diesel, biodiesel burning rate remained nearly constant until the flame extinction limit. The combustion rate of B20 and B50 displayed a mixed behaviour of both parent fuels. Nevertheless, both blends showed that diesel had predominance over the burning rate. Finally, the droplet flame extinction of all fuel droplets occurred at turbulent velocity slightly greater than the laminar flame speed.

Droplet vaporization and combustion of biodiesel, diesel and their blends was examined experimentally in a turbulent flow at elevated ambient temperature and pressure conditions. A high pressure vessel capable of generating high levels of turbulence was employed in this study. The linear relationship between turbulence intensity and fans rotational speed, which was developed at room temperature, was found to be unaffected by the gas ambient temperature. Droplet vaporization experiments were performed by varying turbulence intensity (i.e., the fans rotational speed) from 0 up to 3.1 m/s, ambient temperature and pressure up to 473 K and 16 bar, respectively. The results revealed that diesel droplet vaporization did not follow the d2-law under the aforementioned test conditions. However, biodiesel droplet vaporization obeyed the d2-law. Droplet vaporization of the blends, i.e. B20 and B50, displayed a mixed behaviour of both parent fuels with the biodiesel behaviour predominating where biodiesel content slows down the droplet vaporization of the blends. Turbulence was found to reduce the droplet lifetime of all fuels (i.e., increases droplet vaporization rate), and its effect becomes more effective with increasing ambient pressure. Droplet combustion experiments were performed by varying turbulence intensity from 0 up to 1.20 m/s, and ambient temperature up to 423K at ambient pressure of 1 atm. Diesel droplet combustion rate showed negligible change with turbulence intensity up to 0.40 m/s beyond which the burning rate decreased slightly with turbulence intensity. Similarly, biodiesel droplet combustion rate did not show an increase with the presence of a turbulent flow around the droplet. However, in contrast to diesel, biodiesel burning rate remained nearly constant until the flame extinction limit. The combustion rate of B20 and B50 displayed a mixed behaviour of both parent fuels. Nevertheless, both blends showed that diesel had predominance over the burning rate. Finally, the droplet flame extinction of all fuel droplets occurred at turbulent velocity slightly greater than the laminar flame speed.

Thesis (Ph. D.)--Carleton University, 1996. / Also available in electronic format on the Internet.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18086号 / 理博第3964号 / 新制||理||1571(附属図書館) / 30944 / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)教授 平田 岳史, 教授 田上 高広, 准教授 三宅 亮 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM