The Microscope - Volume 67, Fourth Quarter 2019

IN THIS ISSUE:

On the cover
Digital imaging median filters applied to an SEM micrograph of a single pollen grain. These filters reduce noise in digital images for the purpose of defining object boundaries and attaining accurate image measurements. See Object Boundaries in Digital Images, page 159. (Courtesy of John C. Russ)

Editorial | Write What You Know

Dean Golemis
The Microscope 67 (4), p ii, 2019
Excerpt: “Poetry surrounds us everywhere, but putting it on paper is, alas, not so easy as looking at it.” — Vincent Van Gogh
The same can be said about analytical research. There is no shortage of microscopic matter to study in this world, but committing the research to paper for everyone else’s edification is harder to accomplish. What comes fairly easy in the laboratory doesn’t necessarily translate so smoothly onto paper (or computer monitor). It can be a gnawing task to clearly transmit information through the written word, while wrestling with a train (wreck) of thoughts. Here are some well-known reasons why writing can be a struggle:

• finding the clarity to organize thoughts
• the tyranny of perfectionism: that dastardly inner critic
• lack of writing experience or self-confidence
• and the classic: fear of a blank page!

These are not insurmountable challenges.

Detection of Erionite and Other Zeolite Fibers in Soil by the Fluidized Bed Preparation Methodology

David Berry, Jed Januch, Lynn Woodbury, and Douglas Kent
The Microscope 67 (4), pp 147 – 158, 2019
Abstract: Erionite is a zeolite mineral that can occur as fibrous particles in soil. Inhalation exposure to erionite fibers may result in increased risk of diseases, such as mesothelioma. Low level detection of mineral fibers in soils has traditionally been accomplished using polarized light microscopy (PLM) methods to analyze bulk samples providing detection limits of around 0.25% by weight. This detection level may not be sufficiently low enough for protection of human health and is subject to large variability between laboratories. The fluidized bed asbestos segregator (FBAS) soil preparation method uses air elutriation to separate mineral fibers, such as erionite, from soil particles with higher aerodynamic diameter and deposits those mineral fibers onto filters that can be quantitatively analyzed by microscopic techniques, such as transmission electron microscopy (TEM). In this study, performance evaluation (PE) standards of erionite in soil with nominal concentrations ranging from 0.1% to 0.0001% by weight were prepared using the FBAS soil preparation method and the resulting filters were analyzed by TEM. The analytical results of this study illustrate a linear relationship between the nominal concentration of erionite (as % by weight) in the PE standard and the concentration estimated by TEM analysis expressed as erionite structures per gram of test material (s/g). A method detection limit of 0.003% by weight was achieved, which is approximately 100 times lower than typical detection limits for soils by PLM. The FBAS soil preparation method was also used to evaluate authentic field soil samples to better estimate the concentrations of erionite in soils on a weight percent basis. This study demonstrates the FBAS preparation method, which has already been shown to reliably detect low levels of asbestos in soil, can also be used to quantify low levels of erionite in soil.

Object Boundaries in Digital Images

John C. Russ
The Microscope 67 (4), pp 159 – 169, 2019
Abstract: Determining the boundaries of objects from digital images, which is important for their measurement, is often a challenge. Limitations are imposed by non-uniform lighting or density, optics, dimensions of solid-state detector arrays, noise, and pixelation of the image. A wide variety of computer algorithms illustrated here seek to address these problems, but there is no universally optimum solution. Often, the goal is to achieve repeatability on a particular class of images and objects rather than absolute accuracy.

Critical Focus | Ten Years and Counting

Brian J. Ford
The Microscope 67 (4), pp 171 – 182, 2019
Excerpt: Since debuting a decade ago, this column has provided a refuge for revolutionary ideas, unasked questions, and microscopical insights that apply to today’s scientific problems.

The Microscope Past: 50 Years Ago | A Simplified Technique for Sharpening Steel Microtome Knives

D.W. Quackenbush
The Microscope 67 (4), pp 183 – 186, 2019
Originally published in The Microscope, Vol. 17, First Quarter, pp 55 – 61, January 1969.
Introduction: In the past, the sharpening of steel microtome knives has been a serious problem in this laboratory. Many coated paper and paperboard samples are cut in cross section on the microtome to thicknesses of from three to seven micrometers. Tough epoxy resins have been found to be most suitable for embedding these coated paper samples. These embedding resins require a heavy duty sliding microtome and heavy duty rigid knives which need to be sharp and uniform. The abrasive pigments in many paper coatings dull the knife edge rapidly so that frequent sharpening is required. Commercial sharpening services were tried and usable edges were obtained; however, results were not always consistent and a large inventory of knives was required. It became imperative that a rapid method for sharpening knives to a consistent edge be developed in the laboratory.

The Microscope: Author and Subject Indexes: Volume 67, 2019

The Microscope 67 (4), pp 187 – 191, 2019

Afterimage | Thousand Islands

Jan Burmeister and Martin Dähnrich
The Microscope 67 (4), p 192, 2019
Polymer pyrolysate droplets condensed on a low-e microscope slide; composite photomicrograph. Most Unique winner of the Inter/Micro 2019 Photomicrography Competition. See Inter/Micro 2019 — International Microscopy Conference, The Microscope, Vol. 67, Third Quarter, 2019