The Canadian Penning Trap (CPT) mass spectrometer at the Argonne National Laboratory makes precise mass measurements of both stable and unstable nuclides. To date, more than 60 radioactive isotopes having half-lives as short as one second have been measured with the CPT with a mass precision approaching 10 ppb. This thesis will present measurements made of nuclides along the rp-process path, which describes a process resulting from a series of rapid proton-capture reactions in an astrophysical environment. One possible site for the rp-process mechanism is an x-ray burst which results from the rapid accretion of hydrogen and helium from one star onto the surface of its neutron star binary companion. Mass measurements are required as key inputs to network calculations used to describe the rp-process in terms of the abundances of the nuclides produced, the light-curve profile of the x-ray bursts, and the energy produced. This thesis will describe the CPT apparatus, explain the method used to make precise mass measurements, and present the masses of the "waiting-point" nuclides ⁶⁸Se and ⁶⁴Ge. The mass measurement results, when used in x-ray burst models, confirm both ⁶⁸Se and ⁶⁴Ge as waiting-point nuclides which delay the rp-process by approximately 30 s and 7 s respectively. / October 2005

Air is one of the most important resources in the world and is essential for life. With the development of industry, air pollution is becoming a severe problem. Air Pollution not only affects the quality of the air we breathe; it also impacts the land and the water. Volatile organic compounds (VOCs), which can cause short-term and long-term health problems, are found as contaminants in both indoor air and the environment. Therefore, it is necessary to develop accurate and convenient sampling methods to determine VOCs at trace levels in both community and occupational environment. The focus of this project is to develop the needle trap devices (NTDs) with appropriate sorbents and employ them to do air samplings by diffusive or active sampling mode. For diffusive sampling, the NTD with sorbent Carboxen1000 was developed to monitor benzene, toluene, ethylbenzene and o-xylene (BTEX) in the air, coupled with GC-MS. The factors such as sorbent strength, response time, face velocity, temperature and pressure, relative humidity and sampling duration were investigated. Method validations were done both in the laboratory and in field. The results demonstrate that the NTD with Carboxen1000 is a successful diffusive sampler for monitoring Time-weighted average (TWA) concentrations of BTEX. On the other hand, the NTD with divinylbenzene (DVB) coupled with GC-MS by thermal desorption was developed for sampling and analysis of volatile thiols. The factors such as sorbent strength, desorption efficiency were investigated. The applications, such as vegetable analysis and field sampling analysis, indicate that the NTD with sorbent DVB is a successful active sampler for determine volatile thiols in food and air samples.

This research evaluates the decomposition of leaf litter while in litter traps. More specifically this study asks, ‘Does sugar maple (Acer saccharum Marsh.), American basswood (Tilia Americana L.) and American beech (Fagus grandifolia Ehrh.) leaf litter collected bi-weekly from litter traps undergo a loss of dry mass and nutrient content (C, N, P, K, Ca and Mg) in comparison to freshly abscised leaf litter?’The objective of the initial experiment was to determine if sugar maple, basswood and beech leaf litter collecting in litter traps, while exposed to in-situ conditions, experienced decomposition. Results indicated that sugar maple, basswood and beech leaf litter experienced early stages of decomposition and identified precipitation, freezing temperatures and microbial activity as possible mechanisms for the observed decomposition. It was found that the dry weight of sugar maple and basswood differed significantly (p < 0.05 and p < 0.10, respectively) post- 14-day experiment period as compared to the initial dry weight. Consequently, three experiments were completed to examine the aforementioned variables. Conclusions were based on measured changes in the mass and nutrient (C, N, P, K, Ca and Mg) content of freshly abscised sugar maple, basswood and beech leaf litter under ex-situ conditions. It was found that the dry weight sugar maple and basswood leaf litter exposed to 30 mm, 60 mm and 100 mm of precipitation differed significantly (p < 0.05) as compared to freshly abscised leaf litter. In general, this research affirmed that precipitation and freezing temperature contribute to a change in mass and nutrient content of leaf litter collecting in litter traps. Furthermore, through measurable production of CO2 and Community Level Physiological Profiling it was determined that microbes are present and active on the leaf surface and contribute to the decomposition of leaf litter in litter traps.

Despite chronic dialysis treatment, patients with end stage renal disease undergoing maintenance haemodialysis (HD) remain at a substantially increased risk of morbidity. Previous reports using Doppler ultrasound (DU) during HD have revealed microembolic signals (ME) in the venous circulation. In vitro studies confirm the emergence of microbubbles of air that may pass the security system of the HD circuit without triggering the alarm. The aim of this thesis was to elucidate the presence of ME during HD and examine methods that might reduce exposure to ME in vivo. The first study utilized DU to verify the presence of ME in 40 patients during standard HD. Investigation within 30 minutes after the start of HD and just before the end of session revealed the presence of ME in the venous blood line during both phases. The air trap did not alert for the presence of ME. This indicated that ME may pass into the patient during the entire HD run. Study 2 analyzed the presence of ME prior to start and during HD when measured at the AV-access and also carotid artery. A total of 54 patients were examined using DU as the investigative technique. ME increased significantly after start of HD in the AV-access, but also at the carotid artery site. These data indicated that ME can enter the body and even pass the lung barrier. The question arose if microbubbles of air are resorbed or may cause ischemic lesions in organs such as the brain. Study 3 examined whether the amount of ME detected in the AV-access would change by using either a high or a low blood level in the venous air trap/chamber. This was a prospective, randomized and double-blind study of 20 HD patients who were their own controls. After 30 min of standard HD, measurement of ME with DU was performed for two minutes. The chamber setting was changed and after another 30 minutes a new recording was carried out for two minutes. Data showed that setting a high blood level significantly reduced the extent of ME that entered the patient. The results also indicated that ME consisted mainly of microbubbles. In study 4, twenty patients were randomized in a cross-over setting of HD. Three options were used: a wet-stored dialyzer with high blood level (WH) and a dry-stored dialyzer using either a high (DH) or a low (DL) blood level in the venous chamber. The exposure of ME, detected by DU, was least when using mode WF, more with mode DH, and most with mode DL. There was a correlation between higher blood flow and more extensive exposure to ME. Study 5 was an autopsy study of a chronic HD patient with the aim of searching for microbubbles deposited in organs. Microbubbles of gas were verified in the vessels of the lungs, brain and heart. By using a fluorescent stain of anti-fibrinogen it was verified that the microbubbles were covered by clots that had to be preformed before death occurred. This indicated that air microbubbles are not completely absorbed and could result in embolic deposition in the organs of HD patients. In conclusion, these in vivo studies showed that ME pass the air trap without inducing an alarm and enter the venous blood line of the patient. The data confirmed the presence of ME in the AV-access and also in the carotid artery. Autopsy data of a deceased HD patient demonstrated the presence of microbubbles in the capillaries of the lungs, but also in the systemic circulation such as in the brain and the heart. A high blood level in the venous chamber and wet-stored dialyzer can reduce, but not eliminate the exposure to microbubbles for patients undergoing HD.

Air is one of the most important resources in the world and is essential for life. With the development of industry, air pollution is becoming a severe problem. Air Pollution not only affects the quality of the air we breathe; it also impacts the land and the water. Volatile organic compounds (VOCs), which can cause short-term and long-term health problems, are found as contaminants in both indoor air and the environment. Therefore, it is necessary to develop accurate and convenient sampling methods to determine VOCs at trace levels in both community and occupational environment. The focus of this project is to develop the needle trap devices (NTDs) with appropriate sorbents and employ them to do air samplings by diffusive or active sampling mode. For diffusive sampling, the NTD with sorbent Carboxen1000 was developed to monitor benzene, toluene, ethylbenzene and o-xylene (BTEX) in the air, coupled with GC-MS. The factors such as sorbent strength, response time, face velocity, temperature and pressure, relative humidity and sampling duration were investigated. Method validations were done both in the laboratory and in field. The results demonstrate that the NTD with Carboxen1000 is a successful diffusive sampler for monitoring Time-weighted average (TWA) concentrations of BTEX. On the other hand, the NTD with divinylbenzene (DVB) coupled with GC-MS by thermal desorption was developed for sampling and analysis of volatile thiols. The factors such as sorbent strength, desorption efficiency were investigated. The applications, such as vegetable analysis and field sampling analysis, indicate that the NTD with sorbent DVB is a successful active sampler for determine volatile thiols in food and air samples.

This research evaluates the decomposition of leaf litter while in litter traps. More specifically this study asks, ‘Does sugar maple (Acer saccharum Marsh.), American basswood (Tilia Americana L.) and American beech (Fagus grandifolia Ehrh.) leaf litter collected bi-weekly from litter traps undergo a loss of dry mass and nutrient content (C, N, P, K, Ca and Mg) in comparison to freshly abscised leaf litter?’The objective of the initial experiment was to determine if sugar maple, basswood and beech leaf litter collecting in litter traps, while exposed to in-situ conditions, experienced decomposition. Results indicated that sugar maple, basswood and beech leaf litter experienced early stages of decomposition and identified precipitation, freezing temperatures and microbial activity as possible mechanisms for the observed decomposition. It was found that the dry weight of sugar maple and basswood differed significantly (p < 0.05 and p < 0.10, respectively) post- 14-day experiment period as compared to the initial dry weight. Consequently, three experiments were completed to examine the aforementioned variables. Conclusions were based on measured changes in the mass and nutrient (C, N, P, K, Ca and Mg) content of freshly abscised sugar maple, basswood and beech leaf litter under ex-situ conditions. It was found that the dry weight sugar maple and basswood leaf litter exposed to 30 mm, 60 mm and 100 mm of precipitation differed significantly (p < 0.05) as compared to freshly abscised leaf litter. In general, this research affirmed that precipitation and freezing temperature contribute to a change in mass and nutrient content of leaf litter collecting in litter traps. Furthermore, through measurable production of CO2 and Community Level Physiological Profiling it was determined that microbes are present and active on the leaf surface and contribute to the decomposition of leaf litter in litter traps.

Needle trap device (NTD) is a technique that is useful for a wide variety of applications involving the sample preparation of compounds with a wide range of chemico-physico properties, and varying volatilities. A newly designed NTD that improves the performance relative to previous NTD designs is simple to produce is developed. The NTD utilizes a side-hole needle with a modified tip to improve the sealing between the NTD and narrow neck liner of the GC injector, thereby increasing the desorption efficiency. The slurry packing method was applied, evaluated, and NTDs prepared by this method were compared to NTDs prepared using the vacuum aspiration method. NTD geometries including blunt tip with a side-hole needle, tapered tip with side-hole needle, dome tapered tip with side-hole, sliding tip with side-hole and blunt tip with no side-hole needle (expanded desorptive flow) were prepared and evaluated. Sampling performance and desorption efficiency were investigated using automated headspace extraction of benzene, toluene, ethylbenzene, p¬-xylene (BTEX), anthracene and pyrene. The tapered tip and sliding tip NTDs were found to have increased desorption efficiency. SPME and NTDs are valuable sample preparation tools for on-site analysis. Combining both extraction techniques allows for the differentiation of free and particle-bound compounds in a sample matrix. Portable GC/MS instrumentation can achieve fast separation, identification, and quantitation of samples prepared by the above techniques on-site without the need for transport to the laboratory. This minimizes the effects of volatiles lost and sample degradation during storage time. Here, SPME and tapered tip NTDs combined with portable GC/MS are used to investigate free and total emissions of BTEX and select PAHs from gasoline and diesel exhaust. Using the above optimized technologies, cigarette smoke in a smoking area where people were actively smoking and inside a smoker’s car were also investigated. Target contaminants were found in the investigated matrices at ng/mL levels.

The purpose of the SCRIT project is to determine size and shape of short-lived and rarely-produced nuclei by elastic electron scattering, which is the best probe for the structure studies, for the first time. In traditional electron scattering, a solid target having an order of 1023 nuclei/cm^2 is normally used, which is not possible for short-lived and rarely-produced nuclei. In this project a Self Containing Radioactive Isotope Target scheme (SCRIT) is going to be employed. This innovative ion-trap method is shown to be a way to make measurements with a very small amount of nuclei, an order of only 106 nuclei. In order to determine the absolute cross section for elastic electron scattering for structure study, the simulates measurement of the bremsstrahlung from the trapped nuclei is required. Since the bremsstrahlung cross section for a nucleus of the atomic number Z is well know, the precise measurement of the bremsstrahlung provides the luminosity. My theme in this SCRIT project was a construction of a bremsstrahlung luminosity monitor. It consists of a position monitor for measuring the spatial distribution of bremsstrahlung and a Pb-glass Cerenkov detector for energy measurement. My efforts have been mainly devoted to the construction of a position monitor system using fiber scintillators. The construction of the position monitor was divided into five parts; detector construction, support construction, trigger detector construction, software programming, software testing and detector tests. The position monitor consists of two sets of fiber scintillation detectors. Each of them uses 16 fibers, Bicron BCF-10 with a cross section of 2x2mm^2, optically coupled to a multi-anode photomultiplier, (Hamamatsu H6568-10). The position monitor can measure the XY distribution of bremsstrahlung. Strictly speaking, the fiber detector detects not bremsstrahlung directly but electrons and/or positrons by pair creation of bremsstrahlung in a materials. The data acquisition system has been programmed in NI LabVIEW. The software is an advanced X/Y-coordinate counting system, which can additionally preform functions as save data to file and 3D-plot to determine the spreading of the bremsstrahlung luminosity. The results can be saved and transferred online to a server so that is possible to access the data from anywhere. The system has been tested using beta rays from 90Sr source. The results of the test shown that the detectors can detect minimum ionizing particle, i.e. electrons and positrons. The detector and software testings shows that the system is ready to use for luminosity measurements at SCRIT experiment. This system I constructed surely provides a new and useful information for the SCRIT experiments. / SCRIT Project

This research presents the development of an advanced, state-of-the-art optical trap for use in biological materials and nanosystems investigation. An optical trap is an instrument capable of manipulating microscopic particles using the inherent momentum of light. First introduced by Askin et al., the single beam gradient optical trap is capable of generating small forces (~1-100 pN) in a noninvasive manner. As a result, the optical trap is often used to manipulate biological specimen. This research presents the process for the construction of a custom optical trap, the methods to build a controllable optical trap through a traditional fixed gain controller as well as an adaptive controller, and also enables the application of torque to trapped particles. A method of using adaptive techniques for system identification and calibration is also presented. This research has the potential to use forces and torques to affect our understanding of the mechanics of single molecules and motor proteins. This instrument provides a more precise means of manipulating biological specimen as well as a tool for nanofabrication and has the potential to expand the knowledge base of DNA, chromosomes, biomotors, motor proteins, reversible polymers, and can be used to control chemical reactions. The research presented here documents the creation of an optical trap that is sensitive for applications requiring precise displacements and forces, adaptable to a variety of current and future research applications, and useable by anyone interested in researching micro- and nanosytems. / Dissertation

In duplex DNA, guanine radical cations react with water to form mainly 7,8-dihydro-8-oxoguanine (8-OxoG). Understanding for the mechanism for migration of a radical cation (hole) from the site of initial DNA oxidation to a remote guanine is an important step in the process that will lead to a thorough understanding of DNA damage and its repair. The vast majority of charge migration in DNA experiments utilize guanine oxidation as a monitor for charge transfer. The synthesis of a potential monitor for charge transfer through DNA that is independent of guanine oxidation is reported herein. The system is a carbazole moiety covalently attached to the 2O position of uridine which was successfully incorporated into a DNA strand. Carbazole has a low oxidation potential, and will create a deeper trap than guanine during DNA charge transfer. One electron oxidation of carbazole should lead to the formation of its radical cation. The high extinction coefficient of carbazole radical cation should make it clearly observable with UV analysis. Hence a monitor for charge migration in DNA independent of guanine oxidation is obtained.