The Possibility for Iodine Concentration Determination in a Phantom with Known Titers of an Iodine-Containing Contrast Agent, by Using Dual-Energy Computed Tomography

Objective: to study the capabilities of single-source dual-energy computed tomography (DECT) in quantifying the concentration of iodine in solutions.Material and methods. Single-source DECT was performed using a phantom containing a set of 5 tubes with a different titer of the iodine-containing contrast agent Iopamidol. Further, the obtained images were used to construct iodine maps; and the concentration of iodine was measured within the volume of the titrated contrast agent.Results. Despite a high correlation between the measured iodine concentration in solution with the true concentration (Pearson's correlation coefficient r = 0.98; p < 0.01), there is a measurement error that was 4.8 to 23% at different dilutions.Conclusion. Signal-source rapid voltage switching DECT does not allow precise measurements of the true concentration of iodine in solution. To eliminate measurement errors in further in vivo studies using singlesource DECT, it may be that attention must be paid to the measurement of normalized iodine concentration.

On the Observed Inverse Relationship between Rainfall Amount and Dissolved Mineral Content

Rainfall samples collected on the high plains of West Texas exhibit a high degree of variability with respect to the concentration of dissolved solids. That such variations should occur is to be expected, but there remains some uncertainty regarding factors that influence the ionic composition of individual samples. Measurements often show a distinct decrease in concentration with increasing precipitation amount. The reason for this inverse relationship is not intuitively obvious; however, it can be explained from a theoretical perspective. A theory was proposed that describes the concentration of dissolved solids in a collected rainfall sample. The theoretical basis of the derived equation rests upon fundamental principles of conservation of fluid volume and conservation of mass. This equation, which provides valuable insight into the process, suggests that if the rain sampling tube is absolutely clean at the start of a rain event, then the rainfall sample will not be altered by its collection and, therefore, will provide a true measure of rainfall chemistry. However, if windblown dust or other impurities are allowed to deposit in the rain gauge prior to or during the early stages of a rain event, then the concentration of dissolved solids can be very large for small sample volumes and not at all representative of the true concentration within the rain cloud. Results suggest that impurities in the rain sample can be appreciably diluted by the addition of relatively pure rainwater such that the concentration will asymptotically approach the true concentration as the rainfall sample volume increases.

Quantification of N2+ Implanted AES Depth Profiling Data in Al

The nitrogen implanted profile in aluminum generated by 60keV N2+ bombardment is simulated numerically by the Stopping and Range of Ions in Matter (SRIM) program and is fitted analytically by the Schulz-Wittmaack expression. Taking the SRIM simulated profile as true concentration-depth profile of implanted nitrogen in aluminum matrix, the corresponding measured AES depth profiling data of implanted nitrogen are well fitted by the Mixing-Roughness-Information (MRI) model.

A Bayesian precision profile for measuring the quality of immunoassay experiments

A precision profile, the relationship between the concentration of a substance and its measured precision, is a convenient way of conveying the ability of an immunoassay to accurately measure the concentration of a substance in blood serum. A precision profile is characterized by the definition of precision. Historically, precision has been evaluated as the standard error of an estimator of the concentration in a sample conditional on the true concentration. In this paper, Bayesian predictive inference is used to develop a new measure of precision based on the accuracy with which an assay could infer the concentration in a hypothetical new sample. This leads to a natural procedure for evaluating a precision profile that avoids using approximations such as those inherent in traditional methods.

Truly Quantitative EELS Imaging - Let’s Not Settle For Just Pretty Pictures Anymore

The term “quantitative“ means many things to many people. in imaging its value is often discounted to mean only that a more intense region can be said to have more of what is being measured than a less intense region. Others may be more stringent and require an approximately linear relationship between the measured property and image intensity. (This is most often the case in EFTEM and spectrum imaging) Some specimens contain internal references (such as elements with a known stoichiometric relationship) that are sufficient to get to a true concentration calibration for an image. However, in EELS imaging this still doesn’t allow us to get an understanding of our errors and rarely is it helpful in determining detection or quantification limits.A competent high-school chemistry or physics student could tell us that a quantitative measurement includes both a measured value and an estimate of its error.

Inaccurate measurement of a polymeric IgA myeloma protein by nephelometric and fluorometric instrumentation.

The concentration of IgA in a serum was 5.99 g/L as assayed nephelometrically with reagent from one company, but varied between 5 and 3 g/L (for sixfold and 36-fold dilutions, respectively) without giving a definitive answer when assayed with reagent from another source. Immunofixation electrophoresis indicated an IgA lambda monoclonal protein of 45 g/L. Radial immunodiffusion showed two components, having a total concentration of 41 g/L. By fluorometry the IgA was 3.1 g/L. Increasing the dilution caused the (dilution-corrected) lower values to increase. Although the most frequent cause of such discrepant findings is an IgA2 myeloma, which occurs in about one of every 100 myeloma cases, Ouchterlony double diffusion indicated the major component to be IgA1. A polymer, Mr 670,000, was identified by column chromatography. Contrary to the usual behavior of polymers assayed with radial immunodiffusion, which underestimates their concentration, this polymer reached equivalency in agreement with its true concentration as assayed by the Mancini-Heremans technique.