The Microscope – Volume 70, Fourth Quarter 2023
IN THIS ISSUE
On the cover
A section of the royal fern Osmunda regalis cut by hand using a traditional razor to show the vascular cambium and inclusions in the cortical cells. It was stained with hematoxylin, first proposed as a microscopical stain in 1785. See Critical Focus: Microscopy’s Ingenious Legacy, page 163. (Photo: Brian J. Ford)
Editorial | How to Reach Microscopist’s Heaven
Gary J. LaughlinThe Microscope 70:4, p. ii, 2023https://doi.org/10.59082/EQNL6357
Excerpt: Readers of this journal may recall the concept of a “Microscopist’s Heaven,” which was first described by Walter McCrone in his 1999 Inter/Micro conference recap article (“Inter/Micro-99,” The Microscope, 47:2, pp 101–122, 1999). In the introduction, McCrone goes so far as to list, in alphabetical order by last name, 45 candidates who could be assured to earn the honor. He omits at least 20 others because they were close but hadn’t yet met this criterion (yours truly included … or I should say, excluded).
Excerpt: Readers of this journal may recall the concept of a “Microscopist’s Heaven,” which was first described by Walter McCrone in his 1999 Inter/Micro conference recap article (“Inter/Micro-99,” The Microscope, 47:2, pp 101–122, 1999). In the introduction, McCrone goes so far as to list, in alphabetical order by last name, 45 candidates who could be assured to earn the honor. He omits at least 20 others because they were close but hadn’t yet met this criterion (yours truly included … or I should say, excluded).
Microscopy in the Study of Asbestos-Containing Joint Compound and Patching Products, Including Spackling
James R. Millette, Steven P. Compton, and Christopher DePasqualeThe Microscope 70:4, pp. 147–161, 2023https://doi.org/10.59082/PFNO9407
Abstract: Drywall (wallboard, plasterboard, gypsum board) became the common construction material for interior walls in buildings in the later 1940s. Joint compound (mud, spackling, taping compound, joint treatment material) and patching products such as spackle or spackling were used to seal the seams between the boards and cover cracks and nail indentations. Most joint compounds from the 1940s into the later 1970s contained chrysotile asbestos in various formulations. Analyses by microscopy determined the chrysotile asbestos content of samples of Bondex, Georgia-Pacific, and Reardon products to be 1–5%, 3–8%, and 1–2% asbestos, respectively. Information compiled from several sources, including corporate responses to the U.S. EPA Asbestos Information Act of 1988 and other documents, suggest that asbestos-containing joint compounds and patching products from the 1930s into the late 1970s contained chrysotile in the range of 0.5% to 23%, with one company having a few formulations with asbestos levels as high as 45.2%. Although there were no documents showing that amphibole asbestos was intentionally added to joint compounds, there is some evidence of amphibole asbestos fibers in certain joint compound products, probably as accessory minerals with added chrysotile, talc, or limestone. No amphibole asbestos fibers were found in a Georgia-Pacific joint compound product tested using the acid/base digestion preparation procedure. During simulation testing, the asbestos level in the breathing zone of a worker during the mixing of Bondex Joint Compound ranged from 6.9 to 12 asbestos fibers per cubic centimeter of air (F/cc) (phase contrast microscopy modified by transmission light microscopy). The level was below detection during application. During sanding, the asbestos level in the breathing zone of the worker ranged from 1.9 to 5.5 asbestos F/cc. The simulations showed results that were within the ranges reported in the scientific literature for airborne asbestos levels caused by dry mixing and sanding of asbestos-containing joint compound. The sale of joint compound and spackling sold for consumer use with intentionally added asbestos was banned by the Consumer Product Safety Commission in 1977.
Abstract: Drywall (wallboard, plasterboard, gypsum board) became the common construction material for interior walls in buildings in the later 1940s. Joint compound (mud, spackling, taping compound, joint treatment material) and patching products such as spackle or spackling were used to seal the seams between the boards and cover cracks and nail indentations. Most joint compounds from the 1940s into the later 1970s contained chrysotile asbestos in various formulations. Analyses by microscopy determined the chrysotile asbestos content of samples of Bondex, Georgia-Pacific, and Reardon products to be 1–5%, 3–8%, and 1–2% asbestos, respectively. Information compiled from several sources, including corporate responses to the U.S. EPA Asbestos Information Act of 1988 and other documents, suggest that asbestos-containing joint compounds and patching products from the 1930s into the late 1970s contained chrysotile in the range of 0.5% to 23%, with one company having a few formulations with asbestos levels as high as 45.2%. Although there were no documents showing that amphibole asbestos was intentionally added to joint compounds, there is some evidence of amphibole asbestos fibers in certain joint compound products, probably as accessory minerals with added chrysotile, talc, or limestone. No amphibole asbestos fibers were found in a Georgia-Pacific joint compound product tested using the acid/base digestion preparation procedure. During simulation testing, the asbestos level in the breathing zone of a worker during the mixing of Bondex Joint Compound ranged from 6.9 to 12 asbestos fibers per cubic centimeter of air (F/cc) (phase contrast microscopy modified by transmission light microscopy). The level was below detection during application. During sanding, the asbestos level in the breathing zone of the worker ranged from 1.9 to 5.5 asbestos F/cc. The simulations showed results that were within the ranges reported in the scientific literature for airborne asbestos levels caused by dry mixing and sanding of asbestos-containing joint compound. The sale of joint compound and spackling sold for consumer use with intentionally added asbestos was banned by the Consumer Product Safety Commission in 1977.
Critical Focus | Microscopy’s Ingenious Legacy
Brian J. FordThe Microscope 70:4, pp. 163–176, 2023https://doi.org/10.59082/QGBV8515
Excerpt: Beside the high-tech gadgetry in today's laboratory reside the basic stains, reagents, and microscopical techniques that date back to more than a century—and remain essential.
The history of microscopy is often seen as a specialist subject, and one that doesn’t influence us working in today’s busy modern laboratories. But the history is closer than you think. Look around you. Many of those stains that you take for granted are ancient history. Those computers we use, our mobile phones, the digital equipment, and all that glass and plastic gadgetry are new (indeed, by the time you’ve purchased and installed them, they are already out-of-date). But not the essential stains and reagents. Many have unexpected origins, and some of them tell extraordinary tales.
Excerpt: Beside the high-tech gadgetry in today's laboratory reside the basic stains, reagents, and microscopical techniques that date back to more than a century—and remain essential.
The history of microscopy is often seen as a specialist subject, and one that doesn’t influence us working in today’s busy modern laboratories. But the history is closer than you think. Look around you. Many of those stains that you take for granted are ancient history. Those computers we use, our mobile phones, the digital equipment, and all that glass and plastic gadgetry are new (indeed, by the time you’ve purchased and installed them, they are already out-of-date). But not the essential stains and reagents. Many have unexpected origins, and some of them tell extraordinary tales.
Scotch® Magic Tape™ and the Analysis of Settled Dust
Russ CrutcherThe Microscope 70:4, pp. 177–183, 2023https://doi.org/10.59082/AKYO4067
Abstract: An environmental “sticky” tape lift contains hundreds to tens of thousands of individual particles. Each particle is unique, and its optical properties indicate the particle’s identity and history. Environmental particles are not isolated and by association occur with other particles, which may provide information on the source of an individual particle. The physical placement of particles on a surface carries information about the individual particles as well as the microenvironment associated with the surface at that location. Sampling is a destructive process because information is lost no matter how the surface is sampled. Therefore, the chosen sampling procedure must retain the data required for the analysis. Tape lifts can retain data on particle concentrations, particle identification, particle sources, transport mechanisms active at the sample location, and more. The type and quality of tape, how it is processed, and how it is analyzed will affect the extent to which the environment has been characterized. 3M Scotch® Magic™ Tape (Magic Tape) and the light microscope have been used to make tape lifts by the author since 1970 for characterizing environments. The advantages and disadvantages of using this sampling method are briefly discussed.
Abstract: An environmental “sticky” tape lift contains hundreds to tens of thousands of individual particles. Each particle is unique, and its optical properties indicate the particle’s identity and history. Environmental particles are not isolated and by association occur with other particles, which may provide information on the source of an individual particle. The physical placement of particles on a surface carries information about the individual particles as well as the microenvironment associated with the surface at that location. Sampling is a destructive process because information is lost no matter how the surface is sampled. Therefore, the chosen sampling procedure must retain the data required for the analysis. Tape lifts can retain data on particle concentrations, particle identification, particle sources, transport mechanisms active at the sample location, and more. The type and quality of tape, how it is processed, and how it is analyzed will affect the extent to which the environment has been characterized. 3M Scotch® Magic™ Tape (Magic Tape) and the light microscope have been used to make tape lifts by the author since 1970 for characterizing environments. The advantages and disadvantages of using this sampling method are briefly discussed.
The Microscope Past: 45 Years Ago | Köhler Illumination Using Fiber Optics
Frank E. Fryer and Oppenheimer GoldbergThe Microscope 70:4, pp. 185–186, 2023Originally published in The Microscope, Vol. 28, First Quarter, pp 69–71, 1978.
Abstract: A new high intensity light source utilizes a 150 W quartz-halogen lamp and a fiber optics light guide. One end of the light guide is positioned as close as possible to the quartz halogen lamp. The opposite end of the light guide is a cool source of light equivalent in size and position to the filament in a tungsten lamp. If the light guide is regarded as the source then Köhler illumination is possible just as with a filament lamp.
Abstract: A new high intensity light source utilizes a 150 W quartz-halogen lamp and a fiber optics light guide. One end of the light guide is positioned as close as possible to the quartz halogen lamp. The opposite end of the light guide is a cool source of light equivalent in size and position to the filament in a tungsten lamp. If the light guide is regarded as the source then Köhler illumination is possible just as with a filament lamp.
Author and Subject Indexes: Volume 70, 2023
The Microscope 70:4, pp. 177–183, 2023
Afterimage | Benzidine HCl Reaction
Andrew Anthony Havics — pH2, LLCThe Microscope 70:4, p. 192, 2023
Microcrystals of the reaction product formed by the combination of benzidine HCl and ammonium nitrate; parallel polars and Red I compensator. Benzidine HCl has been used as a test substance to identify different clays by forming a colored clay-organic complex. We found that it not only produces a colored reaction, but it also produces an insoluble microcrystalline reaction product with certain clay samples, in particular hectorite clay. In searching for source material for the reaction, we discovered that it reacts with ammonium nitrate. Image size: 1,050 × 700 μm
Microcrystals of the reaction product formed by the combination of benzidine HCl and ammonium nitrate; parallel polars and Red I compensator. Benzidine HCl has been used as a test substance to identify different clays by forming a colored clay-organic complex. We found that it not only produces a colored reaction, but it also produces an insoluble microcrystalline reaction product with certain clay samples, in particular hectorite clay. In searching for source material for the reaction, we discovered that it reacts with ammonium nitrate. Image size: 1,050 × 700 μm
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