The Microscope – Volume 71, First Quarter 2024
IN THIS ISSUE
On the cover
A common main objective stereomicroscope with reflected light incorporating a simple exterior lamp to illuminate the sample. See Illumination Methods for the Stereomicroscope, Including Use of Colored Filters for Image Contrast Enhancement, page 15. (Photo: Wayne Moorehead)
Editorial | John Gustav Delly, Poet of the Microscope
Gary J. LaughlinThe Microscope 71:1, p. ii, 2024https://doi.org/10.59082/PKIJ3072
Excerpt: John Gustav Delly had the gift of poetic thought, vivid imagination, and original creativity. He expressed the beautiful and cherished the written word. Maker, shaper, gatherer, writer, teacher, coworker, and friend. John G. Delly, the poet of the microscope and ancillary things; scientist, author, writer, and true Renaissance man, passed away on April 21, 2024. He was 89.
Excerpt: John Gustav Delly had the gift of poetic thought, vivid imagination, and original creativity. He expressed the beautiful and cherished the written word. Maker, shaper, gatherer, writer, teacher, coworker, and friend. John G. Delly, the poet of the microscope and ancillary things; scientist, author, writer, and true Renaissance man, passed away on April 21, 2024. He was 89.
Forensic Analysis of Recrystallized Inorganic Oxidizing Salts Used in Pyrotechnic-Based Improvised Explosive Devices Using Light Microscopy and Micro-Raman Spectroscopy
Jared Estevanes, Patrick Buzzini, and Geraldine MonjardezThe Microscope 71:1, pp. 3–13, 2024https://doi.org/10.59082/INDJ3392
Abstract: This study aimed to evaluate the advantages and challenges of analyzing post-blast pyrotechnic pipe bombs using a combination of light microscopy and micro-Raman spectroscopy. Two simulated improvised explosive devices (IEDs) were constructed and exploded using pyrotechnics as the main charge and consisted of several different components to simulate common materials that might be found in authentic bombing scenarios. In order to develop a rapid explosives residue recovery technique, a wet and dry swabbing process was compared to determine the most efficient swabbing method of recovery for inorganic oxidizers in post-blast debris. Samples were recrystallized using a water recrystallization method followed by in situ analysis using polarized light microscopy (PLM) and micro-Raman spectroscopy, targeting euhedral and subhedral crystals. While the water recrystallization had effects on the resulting Raman spectrum, such as peak intensity reduction, ultimately, the final salt identifications were not affected. The detection of several inorganic oxidizers post-blast included the identification of potassium perchlorate (KClO4), potassium nitrate (KNO3), and barium nitrate (Ba(NO3)2). The detection of KNO3 using microscopy alone was more challenging due to its relatively low abundance compared to KClO4 but was achieved with micro-Raman spectroscopy. Additionally, the mixing of inorganic oxidizers within single crystals was also observed. The results indicated that the combined approach of microscopy and micro-Raman spectroscopy enabled the successful detection of inorganic oxidizing salts in a post-blast scenario, as well as describing the advantages and limitations of this combination of techniques.
Abstract: This study aimed to evaluate the advantages and challenges of analyzing post-blast pyrotechnic pipe bombs using a combination of light microscopy and micro-Raman spectroscopy. Two simulated improvised explosive devices (IEDs) were constructed and exploded using pyrotechnics as the main charge and consisted of several different components to simulate common materials that might be found in authentic bombing scenarios. In order to develop a rapid explosives residue recovery technique, a wet and dry swabbing process was compared to determine the most efficient swabbing method of recovery for inorganic oxidizers in post-blast debris. Samples were recrystallized using a water recrystallization method followed by in situ analysis using polarized light microscopy (PLM) and micro-Raman spectroscopy, targeting euhedral and subhedral crystals. While the water recrystallization had effects on the resulting Raman spectrum, such as peak intensity reduction, ultimately, the final salt identifications were not affected. The detection of several inorganic oxidizers post-blast included the identification of potassium perchlorate (KClO4), potassium nitrate (KNO3), and barium nitrate (Ba(NO3)2). The detection of KNO3 using microscopy alone was more challenging due to its relatively low abundance compared to KClO4 but was achieved with micro-Raman spectroscopy. Additionally, the mixing of inorganic oxidizers within single crystals was also observed. The results indicated that the combined approach of microscopy and micro-Raman spectroscopy enabled the successful detection of inorganic oxidizing salts in a post-blast scenario, as well as describing the advantages and limitations of this combination of techniques.
Illumination Methods for the Stereomicroscope, Including Use of Colored Filters for Image Contrast Enhancement
Wayne MooreheadThe Microscope 71:1, pp. 15–29, 2024https://doi.org/10.59082/IGXL4569
Abstract: Stereo light microscopes (SLM) or dissecting microscopes are used in many different sciences, industries, and technologies. The objective for the SLM falls into two major categories: common main objective (CMO) using a single objective with prisms that split the image for each eye, and the Greenough style employing one microscope for each eye. In Europe, in the late 1800s, Carl Zeiss in conjunction with Otto Schott, designed a SLM using an Italian prism design that made images of the object correctly oriented. Two main illumination methods used with the SLM are transmitted and reflected light. Transmitted light illumination using a light source built into the base or with an attachable substage base utilizing an external light source. Some manufacturers provide additional illumination methods such as darkfield and polarizing light filters. Reflected illumination using visible light can be divided into five common illumination methods and two different ways to achieve fluorescent illumination. After a brief discussion of types of filters and sources, practical application of reflected light with the SLM substage attachable base with diffuse reflector and colored filters is shown to enhance visibility of certain colored particles while minimizing the visibility of unwanted colored particles.
Abstract: Stereo light microscopes (SLM) or dissecting microscopes are used in many different sciences, industries, and technologies. The objective for the SLM falls into two major categories: common main objective (CMO) using a single objective with prisms that split the image for each eye, and the Greenough style employing one microscope for each eye. In Europe, in the late 1800s, Carl Zeiss in conjunction with Otto Schott, designed a SLM using an Italian prism design that made images of the object correctly oriented. Two main illumination methods used with the SLM are transmitted and reflected light. Transmitted light illumination using a light source built into the base or with an attachable substage base utilizing an external light source. Some manufacturers provide additional illumination methods such as darkfield and polarizing light filters. Reflected illumination using visible light can be divided into five common illumination methods and two different ways to achieve fluorescent illumination. After a brief discussion of types of filters and sources, practical application of reflected light with the SLM substage attachable base with diffuse reflector and colored filters is shown to enhance visibility of certain colored particles while minimizing the visibility of unwanted colored particles.
Critical Focus | My, How Things Change
Brian J. FordThe Microscope 71:1, pp. 30–42, 2024https://doi.org/10.59082/LIOA1075
Excerpt: We are deluged with claims that AI is a revolution, but greater upheavals have created our modern world. We should cherish past accomplishments — and kick that bucket list. To celebrate the 50th article of Critical Focus, here is my latest idea: the negative birthday. Take your age and deduct that from the year when you were born, then you can see just how much science (and society) have changed in a lifetime. The average reader of The Microscope is about 38, born in 1986. Deduct their age from that date and we go back to 1948. The Second World War had recently ended, telephones had operators, hardly anybody had a television (there were only 146,000,000 in the entire U.S.) and McDonald’s was founded only eight years earlier. And 38 is young.
Excerpt: We are deluged with claims that AI is a revolution, but greater upheavals have created our modern world. We should cherish past accomplishments — and kick that bucket list. To celebrate the 50th article of Critical Focus, here is my latest idea: the negative birthday. Take your age and deduct that from the year when you were born, then you can see just how much science (and society) have changed in a lifetime. The average reader of The Microscope is about 38, born in 1986. Deduct their age from that date and we go back to 1948. The Second World War had recently ended, telephones had operators, hardly anybody had a television (there were only 146,000,000 in the entire U.S.) and McDonald’s was founded only eight years earlier. And 38 is young.
The Microscope Past: 30 Years Ago | An Eyepiece Graticule for Photomicrography
Gary Nichols
The Microscope 71:1, pp. 43–47, 2024Originally published in The Microscope, Vol. 42, Fourth Quarter, pp 177–180, 1994.
Abstract: Photomicrographs are used as a permanent record of the particle shape and size of drug powders in pharmaceutical development. Until recently, scale bars have been handdrawn onto the photomicrographs, but this method is not the most satisfactory way of adding an indication of scale. An eyepiece graticule has been designed to be placed in the front focal plane of a projection eyepiece. Using this graticule, a black, rectangular scale bar having an aspect ratio of 10:1 is automatically superimposed onto a photomicrograph.
Abstract: Photomicrographs are used as a permanent record of the particle shape and size of drug powders in pharmaceutical development. Until recently, scale bars have been handdrawn onto the photomicrographs, but this method is not the most satisfactory way of adding an indication of scale. An eyepiece graticule has been designed to be placed in the front focal plane of a projection eyepiece. Using this graticule, a black, rectangular scale bar having an aspect ratio of 10:1 is automatically superimposed onto a photomicrograph.
Afterimage | Sparrow Feather
Sebastian Sparenga — McCrone Research InstituteThe Microscope 71:1, p. 48, 2024
Feather barbs and barbules in crossed polars with a full-wave plate (Red I compensator) above the sample and a quarter-wave plate below the sample, each with their slow directions aligned and parallel to one another; original magnification = 100×.
Feather barbs and barbules in crossed polars with a full-wave plate (Red I compensator) above the sample and a quarter-wave plate below the sample, each with their slow directions aligned and parallel to one another; original magnification = 100×.
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