Determination of nickel in gold-nickel alloys

An ion exchange separation based on the difference in adsorption from a chloride solution combined with an EDTA titration is suggested as a rapid and accurate method for the determination of nickel in nickel-gold alloys.     

Special Issue Article: Preparing for the 21st Century: The Status of Quantitative Literacy in the United States

This article articulates and operationalizes a framework for investigating the level of quantitative literacy in the United States. Quantitative literacy is defined in terms of mathematical content knowledge, mathematical reasoning, understanding of the social impact and utility of mathematics, understanding the nature and historical development of mathematics, and mathematical disposition‐Data from the Third International Mathematics and Science Study are used to document the level of quantitative literacy in the US. Results suggest that, although students in the US seem to possess an awareness of the usefulness of mathematics and have positive dispositions toward mathematics, they fall short in their understanding of the nature of mathematics and an ability to apply their content knowledge to everyday situations. Suggestions for curriculum and instruction that align with the framework for promoting quantitative literacy are offered.     

Developments in MALDI Mass Spectrometry: The Quest for the Perfect Matrix

Abstract

The topic of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has received much attention over the past several years and with the award of the Nobel Prize to Tanaka based on his landmark paper in 1988, has received even more recent attention. This review focuses on the search for an ideal matrix and generally covers the period from the mid 1990's to the present. There have been a number of excellent and comprehensive reviews on MALDI ion formation and a brief summary of some of the most important conclusions is given here. With respect to the applications of MALDI, the present review focuses primarily on polymer analysis, although in this area too, excellent reviews have been published that include consideration of the MALDI method. Although we make some mention of other uses of MALDI (e.g., to proteins and peptides) and other biological applications, we emphasize the polymer uses in the present review.     

Biological Dosimetry by the Triage Dicentric Chromosome Assay - Further validation of International Networking

Biological dosimetry is an essential tool for estimating radiation doses received to personnel when physical dosimetry is not available or inadequate. The current preferred biodosimetry method is based on the measurement of radiation-specific dicentric chromosomes in exposed individuals' peripheral blood lymphocytes. However, this method is labour-, time- and expertise-demanding. Consequently, for mass casualty applications, strategies have been developed to increase its throughput. One such strategy is to develop validated cytogenetic biodosimetry laboratory networks, both national and international. In a previous study, the dicentric chromosome assay (DCA) was validated in our cytogenetic biodosimetry network involving five geographically dispersed laboratories. A complementary strategy to further enhance the throughput of the DCA among inter-laboratory networks is to use a triage DCA where dose assessments are made by truncating the labour-demanding and time-consuming metaphase-spread analysis to 20 to 50 metaphase spreads instead of routine 500 to 1000 metaphase spread analysis. Our laboratory network also validated this triage DCA, however, these dose estimates were made using calibration curves generated in each laboratory from the blood samples irradiated in a single laboratory. In an emergency situation, dose estimates made using pre-existing calibration curves which may vary according to radiation type and dose rate and therefore influence the assessed dose. Here, we analyze the effect of using a pre-existing calibration curve on assessed dose among our network laboratories. The dose estimates were made by analyzing 1000 metaphase spreads as well as triage quality scoring and compared to actual physical doses applied to the samples for validation. The dose estimates in the laboratory partners were in good agreement with the applied physical doses and determined to be adequate for guidance in the treatment of acute radiation syndrome.