Thesis (Ph. D.)--University of Michigan, 1926.

Thesis (M.S.) -- University of Montana, 2007. / Title from author supplied metadata. Description based on contents viewed on August 7, 2009. Includes bibliographical references.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 104-105).

Master of Science / Department of Geology / Saugata Datta / Children are the demographic most susceptible to and affected by lead poisoning. Lead contamination in soil has been recorded as being primarily from lead-based paint, historic leaded gasoline emissions, and from lead point-source emitters. The highest risk of elevated blood lead level (BLL) is correlated with living in an area dominated by pre-1950’s housing. From 1976 to 1994, midst the phasing out and removal of lead from gasoline, the blood lead levels of children in the United States decreased from 16 µg/dL to 3.2 µg/dL. There is evidence showing the irreversible effects of intellectual impairment still occur at levels of BLL below 10 µg/dL. In Kansas, Barton and Ellis counties residential soils were sampled, and chemical composition was examined with a handheld XRF and an HR ICP-MS. Particle size and pH were recorded for all samples. The presence or lack of of lead sulfate and lead carbonate was identified using XRD. Chemical tests revealed elevated Zn and As with increasing Pb concentrations. There was weak evidence of lead sulfate in one of eight tested samples. Barton county has courser sediments and the top five highest Pb concentrations recorded in this study. There is a significant correlation with Pb concentrations and age of housing for houses built prior to1950. Pb Isotopic analysis on eight samples showed multi-source contamination in the soil. We believe the source of most of the lead is from ambient lead mixed with historic leaded gasoline deposits and possible output from factories/coal, along with leaded paint in older homes. Three of the eight samples had paint chips which tested positive for lead. Maps were created showing central Kansas having elevated blood lead levels in children and overlays were made illustrating oil well density in counties. Five variables were used to create a risk assessment map for Kansas: housing age, poverty levels, blood lead levels, number of oil wells, and population.

The dynamic business environment has prompted the companies to improve their competitiveness in terms of manufacturing efficiencies by exploring faster, better and cheaper modes of product development. In this concern, different approaches are configured such as lean manufacturing, just in time and lead time reduction. The study focuses on a critical investigation into the reduction of Lead Time within discrete manufacturing in Kurdistan region of Iraq and the reasons behind this research, that area has evolved gradually as well as the government has an action plan for national recovery and development of reconstruction, where lead-time has become a major issue in manufacturing industry. Specifically, current research study aims at contributing to the strand by focusing on a critical investigation into the reduction of lead time within discrete manufacturing in Kurdistan region of Iraq, where lead-time has become a major issue in manufacturing industry. Mainly, the study has the goals of developing reliable techniques for reducing the lead time through application of assessment survey, capacity planning and key performance indicators in order to implement and control the manufacturing processes. The rationale behind the present study is consisted of economic development within the region, which has attracted a large number of foreign direct investments, but the expanded lead time is causing hurdles with the lack of a strategic plan for resolving the issue which has not keenly addressed in literature so current study would be beneficial for both the stakeholders such as researchers relying on literature and for practitioners as well. In order to conduct the analysis, current research applies the mixture of quantitative and qualitative research. Specifically, for quantitative analysis, a survey is conducted using questionnaires as data collection tool and SPSS analysis for exploring the cause and effect relationship. Mainly, the data are collected from eight Kurdistan based manufacturers. On the contrary, the qualitative analysis is conducted through the case studies. The development of a comprehensive conceptual framework has been applied for focusing on quick response manufacturing both at batch and mass production level. The framework is a contribution to academic knowledge. Through the outcomes of the study, specific factors which are explored to be the main causes of extension in lead time include ineffective forecasting for material requirements, capacity planning, inaccurate demand analysis, decreased resource efficiency and shipment delays. As the most effective solution to these issues, the findings explained that the lot for lot technique is much better than the fixed period requirements which are mostly used in the Iraq region. Moreover, just in time manufacturing strategy and closed loop capacity is also proven to be fruitful along with the splitting order tactic. It is concluded from the findings of this study that the basic issue lies with management in different areas like in human resource, quality, information acquiring, technological developments and operational efficiency. So, it is recommended to the practitioners to higher efficient management squad at the most basic level to eradicate the root cause of the lead time issue. This research will provide new simple strategies for reducing manufacturing lead-time because this is particularly important, as it can be used to provide guidance to industry practitioners on how to reduce manufacturing lead time.

No description available.

The behaviour of lead concentrate particles oxidizing in a stagnant gas reactor has been examined and a mathematical model which predicts the kinetics of galena particles developed. The effects of oxygen concentration, particle size, furnace temperature and concentrate composition were studied. The results showed that the concentrates all exhibited sharply defined ignition points. The ignition points were found to be strongly dependent on oxygen concentration. Reductions in ignition temperature of up to 100 K were observed when the concentrates were reacted in pure oxygen rather than in air. Iron composition was found to have a similar effect on ignition temperature. The modelling results predict short reaction times for ignited particles (less than 100 milliseconds). Particles which ignited in air attained predicted temperatures in excess of 2600 K. In oxygen, particle temperatures were calculated to be greater than 2800 K. Good agreement was found between experimental results and model predictions. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

Forty rats, in groups of ten, were orally dosed with corn oil, corn oil and 2,000 mg/kg trichloroethylene (TCE), corn oil and 2,000 mg/kg lead carbonate, or a mixture of 2,000 mg/kg each TCE and lead carbonate, in an effort to determine whether or not dual administration of both TCE and lead would have an additive effect on neurotoxicity and overall health as indicated by behavioral and physiologic measurements and tissue pathology. A functional observational test battery (FOB) was performed before, during, and after dose administration to assess dose-related changes. The FOB testing assessed behavioral and physiologic measurements such as gait, open field activity, posture, grip strength, and handling reactivity. Pathological examination included assessing dosing related changes in the testis, spleen, heart, liver, kidney-adrenals, and brain. Results indicated that each compound was toxic individually, and that the combination of the two neurotoxicants provided conflicting indications of both reduced and additive toxicity. The toxicity of lead carbonate caused the vast majority of toxic consequences in the study. A reduction in body weight and an increased resistance to cage removal were the only statistically significant changes observed in the FOB that were due to concurrent administration of lead and TCE. Organ-to-body weight and organ-to-brain weight calculations showed evidence of a statistical difference between the lead and lead/TCE dosed animals for liver, kidney-adrenals, and body weight. The significance of these changes is not fully understood. / Master of Science

No description available.

published_or_final_version / Civil Engineering / Master / Master of Philosophy