Statistical Comparison and Evaluation of Analytical Techniques for Measurement of Trace Elements in Coal

Rapid technological advances in industry, transportation, energy production, and agriculture have resulted in increased environmental pollution of toxic materials. Following the passage of federal pollution regulations beginning with the first Clean Air Act Amendments in 1977, industry has become more aware of the environmental consequences of these technological advances. In recent years, there has been an increased effort to improve the quality of life by minimizing pollution on a global scale. The utilization of fossil fuels is one source of toxic materials in the environment. A necessary step to understanding the emissions of toxic metals from combustion and gasification of coal is quantitation of the various elements at all stages of these processes. The analytical techniques used in this investigation were x-ray fluorescence, atomic absorption spectroscopy, inductively coupled plasma atomic emission spectrometry, and neutron activation analysis. The repeatability and reproducibility for each analytical technique was determined for the seven elements of interest using control charts and statistical tests. A statistical comparison of results from different analytical techniques for measurement of seven trace elements (As, Cr, Cd, Hg, Ni, Se, and Pb) in coals was conducted. A comparison of results obtained by chemical fractionation, a selective leaching technique done on coal, was completed. From the this study, a determination of the most appropriate analytical technique for each of the individual trace elements was ascertained

Kikan-Shido : between desks instruction

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Kikan-Shido: through the lens of guiding student activity

The lesson event ‘Kikan-Shido’ (Between Desks Instruction) is used to compare different forms of guidance provided by teachers in mathematics classrooms across six cities. While Kikan-Shido had a recognizable structural form in all the mathematic classrooms in the data set, there was variation in both the amount of time devoted to Kikan-Shido and in the way individual mathematics teachers’ ‘Guided Student Activity’. In this paper, examples of individual teacher guidance are examined to draw out the subtleties of practice in three ‘Asian’ and three ‘Western’ classrooms. It is posited that differences in activity are related to specific pedagogical principles that appear to underlie the teachers’ practice. The occurrence of similarities in practice across apparent cultural categories problematises simplistic East-West comparative cultural analyses

Addressing the challenge of legitimate international comparisons of classroom practice

C1 - Refereed Journal Articl