An alleged opium pipe, purchased from a local antique dealer, is examined by polarized light microscopy to determine the composition of its various components and the composition of the white crystalline material in the container attached to the pipe.
Retiring for a microscopist is different. The curiosity about how the world works remains and the technology is available and inexpensive in contrast to most scientific disciplines. Techniques of sample collection and preparation have been taken to sea. The thin section technique has been particularly successful for examining marine specimens. Stones, sand, and portions of marine organisms have been treated in this manner.
"Crystallization and Polymorphism of Clenbuterol·HCl"
Clenbuterol·HCl is a bronchodilator, indicated for treatment of asthma in horses. It is obtained by crystallization from isopropyl alcohol. X-ray diffraction indicates that this compound forms at least three different polymorphs, referred to as Forms A, B and C. Polarized light microscopical analyses have shown that Clenbuterol·HCl precipitates out of solution as Form C, then undergoes a solid-solid transformation to the thermodynamically stable Form A. In some cases an intermediate form, called Form B, is obtained. Form B is not stable under ambient conditions and will eventually convert to Form A. The Form C polymorph exhibits a prismatic crystal habit. The subsequent A and B polymorphs form prismatic crystalline aggregates, pseudomorphic after Form C. Additionally, Form A may undergo complete recrystallization if enough residual solvent is present. In this case it forms single equant crystals (characteristic of Form A). Data collected to date suggest that the final crystal habit is dependent on the drying conditions of the wet cake, obtained from the crystallization process. This paper will present the results of a crystallization and drying study conducted to test this hypothesis. Optical crystallographic data useful in distinguishing Form A from Forms B and C, will also be presented.
"Optical Properties of Polymorphic Forms I and II of Paracetamol"
Paracetamol (acetaminophen) is a widely used drug for the relief of mild pain and reduction of fever. It has two known polymorphs, which are the commercially used Form I (monoclinic) and Form II (orthorhombic). Although the crystal structures for these were determined more than 20 years ago, their complete optical properties have never been published. Form I is available in bulk quantity as high purity crystals, but it is only recently that suitable quality crystals of Form II have been grown in sufficient quantity for optical characterization. This paper reports the results of detailed optical crystallography studies conducted to characterize the optical properties and optical orientations of both polymorphs. The following properties have been determined for each polymorph: principal refractive indices, optic sign, optic axial angle (2V), dispersion of optic axes, and extinction angle.
"The Microscopical Approach - Keep it Simple"
Industrial microscopists always have a way of ending up in the middle of tense manufacturing situations (if they're lucky). We know that our help is useful if not critical to the manufacturing operation and ultimate product improvement. Pharmacia & Upjohn is a pharmaceutical company, producing bulk pharmaceutical chemicals for internal use and external sale and a wide array of pharmaceutical product forms. This broad manufacturing experience and international scope provides ample opportunity for a microscopist's involvement. We have the added challenge of exporting our expertise within the "fence" of the global company. Examples of tablet, sterile solution and lyophilized powder parenteral product case histories will be provided. The analytical approach and examples presented in this paper will be applicable in many manufacturing scale-up and process control projects.
"Quinoline as a Microchemical Reagent"
Quinoline is briefly described in The Encyclopedia of Microscopy as a useful reagent for certain metal ions, but it is curiously absent in other works on microchemical tests. Therefore, I decided to investigate. I plan to review microchemical tests using quinoline and to determine its merits as a reagent.
"Putting the Chemistry Back into Chemical Microscopy"
The dry lab, which was formerly a derogatory term for laboratory work that was never performed, has come to symbolize the modern analytical laboratory where the only chemicals are the samples themselves. It is incorrectly assumed by many analysts today that this is as it should be and that instruments such as infrared microspectroscopy and energy dispersive X-ray analysis can answer all the analytical questions which might arise. Twenty-five years of professional experience and another nineteen as an enthusiast, have convinced us that this is not the case and that classical microchemistry is more important than ever when used in intelligent conjunction with these and other instruments. This viewpoint will be illustrated by means of examples from recent projects from our practice. We hope to prove that microchemical methods are dismissed as old fashioned only by those who do not have the skill or experience to use them as they should be.
"Are They Really Thermal Standards"
Several twenty-year old thermal standards in the laboratory chemical cabinet were suspect as to their reliability. Thus, it was decided to perform Differential Scanning Calorimetry (DSC) on them to determine if they still were standards. The results of the testing show that most of the materials still had the same melting points as indicated on their respective bottles.
"A Method of Preparing Students for a "Close Encounter" with Particle Analysis"
I use the McCrone system of binary classification of particles in the process of training students to observe and record observations accurately. Many students find it very difficult to proceed from the observation level to an abstract level of describing observed images. Bridging this conceptual barrier, utilizing an overhead projector in classifying particles, will be demonstrated.
"Sample Polishing Can Be Easy and Fast"
Chemical-Mechanical Polishing (CMP) has been widely used in the semiconductor industry for manufacturing integrated circuits and memory discs. It uses nanometer abrasive particles combined with water and oxidation chemical components to polish semiconductor wafers and rigid discs on a polymer pad. Generally, the polishing rate ranges from 0.2 µm/min to 0.8 µm/min depending on the materials to be polished. The average surface roughness can be as low as 4 . The thickness variation of the flatness of an 8" wafer is less than 5%. Even though CMP has become the process of choice in the high-technology industry, the mechanisms have not been thoroughly understood. The authors use the CMP method to polish a few metal blocks in a metallography sample preparation lab on a conventional polisher. By using the one-step CMP method, the tungsten block was polished to a mirror surface within a few hours. A copper sample was polished within a few minutes. Some other metals and oxide materials were also polished. In this work, the authors discuss the mechanisms of CMP, and demonstrate CMP as an adaptable method for sample preparation in metallography.
The principles of the origin of the interference colors displayed by anisotropic specimens as seen between crossed polarizers are reviewed as a prelude to the origin of the interference colors as seen between parallel polarizers. The advantages and historical applications of this seldom-used technique will be discussed and illustrated.
"Microscopical Methods for Measuring Metastability in Industrial Crystallization"
The academic definition of metastability is the zone in a solubility curve where there is supersaturation but no spontaneous nucleation or crystallization. A more practical form of metastability is the zone where growth exceeds nucleation; beyond this, most systems will not produce the large single crystals desired in industry. Both can be difficult to measure by macro methods. It has been found that "micro test tubes" consisting of droplets of one liquid suspended in another form an ideal device for these determinations. Water in oil and toluene in water are two such systems. Advantages are good temperature control, no evaporation to influence supersaturation, the use of very small quantities where the substance or modifier is costly, direct observation of the nucleation/growth process and the ability to very rapidly determine both academic and practical types of metastability.
"Determination of Grain Orientation in Rolled Aluminum-Lithium Sheet Using the Polarizing Light Microscope"
Determining grain orientation (microtexture) in Al-Li alloy sheet is important for the correlation of mechanical properties with microstructure. Development of a simplified optical method using a polarized light microscope to determine grain orientation could provide a simpler, faster and less expensive alternative to X-ray diffraction methods. This paper presents the status of ongoing work to correlate optical information from anodically etched aluminum with grain orientation determined in the scanning electron microscope using electron backscattered pattern analysis. It is possible to differentiate between grains with a (100) plane parallel to the surface and those with a (110) plane parallel to the surface based on the retardance of the anodic layer when viewed with crossed polars in a polarized light microscope. This study shows that the anodic layer viewed with crossed polars acts as a transparent, anisotropic crystal whose slow axis, or axis of highest retardance, can be determined with polarized light microscopy. The slow axis of the anodic layer has been found to be coincident with the longest axis, in projection, of the alloy crystal. For grains with a (110) plane parallel to the surface this latest finding can be used to determine the specific orientation can be determined using this new information. This represents a significant step towards realizing the goal of developing a fast inexpensive technique using optical microscopy for the determination of grain orientation in Al-Li sheet.
"Quantitative Methods for Estimating the Refractive Index Difference Between a Solid Particle and an Immersion Liquid"
The essence of the immersion method is to estimate the refractive index (RI) of a solid particle by immersion in a refractive index liquid. For each mount, one has to determine whether nL (RI of liquid at 589.3 nm, the wavelength of the Fraunhofer D line or sodium light) is equal to nS (RI of solid at 589.3 nm). If the answer is 'yes', the measurement is complete. If the answer is 'no', one has to determine whether the liquid RI is higher or lower than the solid RI and, based on that assessment, select another liquid for the next mount. If one could determine both the sign and magnitude of the RI difference between the liquid and the solid, the selection of the next liquid becomes a much more objective and quantitative decision. When the difference (nS - nL) is small enough, or the RI difference estimation is sufficiently accurate for the specific purpose of a measurement, one can immediately obtain nS/D by adding the estimated (nS - nL) to the nominal nL of the liquid used without having to prepare another slide mount.
Based on algorithms outlined by the author (1993), methods have been developed to quantitatively estimate the difference between nS and nL or (nS - nL) according to the Becke line characteristics and dispersion staining colors. A series of charts have been generated to facilitate the estimation of (nS - nL) in circumstances with or without the knowledge of the dispersion coefficient of the solid to be measured. The application of these methods to asbestos identification is discussed in detail with special charts constructed for this analysis.
"Solution of Three Troublesome Microanalytical Problems"
Titanium white is identifiable by PLM but another microchemical test for titanium would be helpful. Another problem is the differentiation between the bast fibers: linen, hemp, jute, and ramie. Rapid dependable procedures are proposed. Finally, for good measure, there is a way to recover a particular single particle from a mixture of many other particles all immersed in Aroclor 5445 under a coverslip.
"Photophysical Characterization of Liquid Crystalline Polymer Thin Films Using Polarized Light Microscopy in the Near and Far-Fields"
There is great interest in studying the fluorescence properties of conjugated polymers because of their potential use in lasers and organic light-emitting diodes. Recent studies have shown that fluorescence is reduced when polymer chains interact, and our studies provide new insight into the mechanisms of these inter-chain interactions. Polarized Light Microscopy (PLM) and Near-field Scanning Optical Microscopy (NSOM) are used to study the morphology and optical properties of polymer films and to understand the relationship between inter-chain interactions and the length of the alkyl substituent in a series of polyfluorenes bearing two hexyl, octyl, and dodecyl substituents at the 9 position.
"Mysteries of a Butterfly Wing"
The wing of a Morpho butterfly is covered with a most complex structure of scales. Those scales attached to the brown bottom-side of the wing are pigment-colored, however there is periodic structural banding present consistent with a diffraction grating for the UV range. The color of the iridescent blue top side of the wing are not produced by pigments; rather the colors of the scales are formed in an intricate network of ridges laminated so that the layers act as multilayed interference filters. There is present a periodic fine pattern consistent with UV diffraction gratings.
Why has such a complex structure evolved? The presence of scales can be advantageous in improving aerodynamics for flight. In addition, scales which are easily detached would help free the wing if caught in a web, though the loss of scales would hinder flight. The presence of the iridescent blue color is indeed a paradox. Rather than being camouflaged to evade a predator, the brilliant blue color is extremely conspicuous so as to attract attention. On the other hand it is possible that flashing such a vivid color could startle or confuse an attacking predator. A likely function of such a distinct color is to be a sex attractant as might be the UV pattern produced by the diffraction grating-like structure of the scales.
Several studies have been made to emulate some of the unique properties of butterfly scales to technology.
"EDS in the ESEM"
The environmental scanning electron microscope images nonconductive, hydrated materials without the need of a high vacuum or a conductive coating. This is accomplished by the presence of water vapor in the specimen chamber. The water vapor scatters the electron beam creating a 'skirt' of electrons at the specimen surface. This skirt can degrade the quality of energy dispersive x-ray spectrometry results since x-rays can be generated many millimeters from the beam target. This problem can be minimized by optimizing the ESEM operating conditions for EDS. Generally, this requires that the accelerating voltage be maximized, the gas path length minimized and the chamber vapor pressure minimized. With this optimization, it is possible to conduct qualitative analyses of solid phase synthesis products on polystyrene beads and to conduct quantitative analyses of a gold/copper NIST standard with the same accuracy and precision as with a traditional SEM. Other examples of the use of EDS in the ESEM for particle contaminant identification will be provided.
"A Drawtube-Mounted Low Magnification Objective and Bertrand Lens"
A drawtube was added to a 'student POL microscope' made from an Edmund Scientific Monolux biological microscope to allow use of 215 mm tube length metallurgical objectives with a homemade vertical illuminator. The 160 mm tube length biological objectives up to 0.65 N.A. can be satisfactorily used in place of the metallurgical objectives. The end of the drawtube was threaded to mount a 50 mm focal length macro lens salvaged from a slide copier. A field size of 10 mm can be viewed with this lens through an open position in the lens turret in brightfield or darkfield polarized light. The same lens serves as a Bertrand lens to view interference patterns in the exit pupil of the 0.85 N.A. objective.
"Relay Lens Considerations for Digital Photomicroscopy"
Compensating eyepiece systems to correct for chromatic difference of magnification in the intermediate image are common in older microscopes. Sometimes the compensation also includes correction for field curvature in the intermediate image. Accessory relay lenses to couple CCD cameras to microscopes commonly do not compensate the intermediate image for color or curvature of field. These noncompensating optics relay lenses can be successfully used on older Zeiss microscopes using monochrome cameras with heavy green filtration.
"An Investigation of Chromatic Difference of Magnification in Digital Images"
The advantages of digital micrography have led many microscopists to adapt their existing, and in many cases, older microscopes for digital imaging. The adapter used to mount the camera on the microscope can have a significant impact on the quality of the digital micrograph. If the adapter replaces a compensating eyepiece, then the CDM, chromatic difference of magnification, due to the objective may be evident. Illustration of the effect on the digital images from microscopes of various ages and manufacturers will be shown.
"Surface Imaging-Reflected Light Nomarski Interference Contrast (NIC) vs. SEM"
Surface imaging for texture comparisons and small defect location can be done by a variety of techniques. Scanning probe microscopes are used for extremely fine features on flat surfaces. Scanning electron microscopes are frequently used for metal surfaces such as fracture faces and etched surfaces. Metallographs are used for examining polished metal specimens to visualize grain boundaries and microcracks.
Surface imaging of polymers can be done by these and other techniques. Scanning electron microscopy is gaining more popularity for polymer surface imaging especially since the introduction of field emission systems. The FESEM can provide high resolution images at low electron beam accelerating voltages (0.5-1.0 kV). At lower beam voltages, the electrons cannot penetrate more than 1-2 micrometers, thus producing better surface images. Conductive coatings, such as gold, gold/palladium and chromium, are usually applied to polymers (not always needed for FESEM low voltage work) but they can produce surface texture artifacts from heat damage or aggregates of the metals. A major factor against the FESEM is cost, which can be from $500,000 - $1,000,000 and it may not be the right instrument for polymer surface imaging.
Reflected light NIC attachments for a polarized light microscope can be purchased for <$5,000. NIC is a little used (or generally forgotten) technique for surface imaging that works extremely well on polymers. Reflected light NIC outperformed the FESEM for surface imaging on an interior steel can coating and for surface texture imaging on the interior wall of plastic tubing as shown by examples. If polymer surface imaging is the main goal, NIC should be given serious consideration before purchasing much more expensive equipment.
"A New Microscope System for Infrared Microspectrometry"
A new microscope accessory for infrared microspectrometry is described. This development is based on using infinity-corrected all-reflecting optics and features a unique bifunctional sample masking system. The design goals were to increase optical efficiency, provide confocal sample masks using a single mask, improve image quality, simplify operation and reduce cost. This FT-IR accessory microscope has coaxial paths for light and infrared radiation. A single mask in a field plane defines the sample area irradiated by the infrared beam on its path to the sample and as this beam returns from the sample to the detector. This single mask is used in both transmission and reflection modes. The single mask simplifies the operation of this microscope for infrared spectral measurements. The Schwarzschild reflection microscope objective lens has much less spherical aberration when it is configured for infinity correction. The reduction in spherical aberration improves image quality and through-put efficiency.
"A Little Carbon, A Little Magic"
A new engineering material made by synthesis in RF plasma from hydrocarbon gas and hydrogen is commonly called diamond-like carbon. It is not really carbon, nor is it diamond but it has many of the desirable properties of diamond. We have attempted to characterize this material with several conventional microanalysis techniques before finally deciding that FT-Infrared spectroscopy is the most definitive. The mystery is what the unusual spectra are telling us.
"Designing a Laser Microscope for Space"
The European Space Agency will launch a small microscope into space early in the new millennium, with the intention of observing cell aggregates under conditions of microgravity. The project was contracted to us by Brunel University. Analysis of the design and its rationale allowed some components to be omitted, and others modified. More than fifty percent of the volume, and sixty percent of the mass, was eliminated. Today the project will be described with video recordings of the research.
"Development of a Phosphorescence Microscope"
Phosphorescence is light emitted by a substance after exposure to actinic radiation. It differs from fluorescence in that fluorescent light is emitted promptly upon excitation-typically within nanoseconds of illumination-while phosphorescent emission develops over a period of illumination which may be a millisecond to days.
Phosphorescence exhibits a more complex behavior than fluorescence, and can have an elaborate spectrum due to the presence of impurities or even crystal defects. For this reason it has potential for forensic use in answering the class of question "Did this piece of paper come from the same batch as any of these known samples?"
The difficulties of constructing a microscope that is capable of observing and photographing phosphorescent samples center about
(1) The extreme weakness of the emission;
(2) The choice of a suitable illuminating source;
(3) The difficulty of exciting the sample without blinding the observer.
I will discuss these problems and show results from a prototype which solves them more or less well.
"Multi-Order Retardance Measurements with the LC-PolScope"
We will report on progress in the development of a retardance imaging system capable of measuring multiple order retardances. The system is based on the LC-PolScope, using a liquid crystal compensator and CCD camera to measure sample retardance at all CCD image points simultaneously. Whereas the LC-PolScope measures retardances from 0.05 to 273 nm at a wavelength of 546 nm, the new system, called Multi-Order PolScope (MOPS), measures up to 5500 nm of retardance using multiple wavelengths. Data are shown of quartz wedges and selected polymer fibers. MOPS also provides a sensitive means for characterizing birefringence dispersion.
"Experiments with the LC-Pol Microscope from CRI"
Several applications of the precision universal compensator imaging system of CRI are presented. At this time, the applications are limited to retardation values in the first order. Aspects of the method to be discussed include documentation of the retardation of very fine fibers, correlation between changes in shape and retardation, and the prospect of summing the overall retardation for a particle.
"The Jungle of Infinity Optics: Concepts and
Over more than the last decade all four major microscope manufacturers, Leica, Nikon, Olympus and Zeiss have departed from the traditional "standard" in the design of microscopes and gone to so called "Infinity Correction". We will compare the new design concepts and explore the reasons, the benefits and some not so obvious consequences.
"Multi-Spectral Imaging for the Microscopist - a Simplified Approach"
To evaluate a heterogeneous sample for its spectral signatures it is typically expensive if a spectrometer can be found that will fit a routine microscope. The PARISS Imaging Spectrometer simply screws into the video port of any microscope.
The spectra can be acquired of up to 100 objects simultaneously over the range 380 to 800 nm, and presented to the researcher as a spectral topography map. The CCD-based spectrometer system uses a second CCD camera to acquire a video image to enable the location of a spectrum to be correlated with the visual aspect. The spectra of objects down to 0.5-micrometer can be acquired and processed with a powerful Neural Network data processing engine.
One of the major hurdles of multi-spectral imaging has been the speed of data analysis - PARISS has resolved this issue with near real-time presentation of results.
"Some Uses of Crystal Plates in Microscopes"
Compensators of one lambda or lambda/4 retardation are indispensable to identify and localize the planes of vibration of the slow and fast ray of anisotropic microscope specimens. Less obvious is the purpose of using fixed crystal plates inside the binocular tubes of polarized light microscopes and the use of quarter-wave plates in the coaxial illuminators.
"A New Stereo Fluorescence Microscope from LEICA"
A fluorescence zoom stereo microscope is introduced that incorporates a separate, pancratic illumination path. This results in brighter, more contrasty fluorescence images and offers additional benefits when used with conventional, quasi-coaxial white light illumination.
"Microscopical Characteristics of Pen/Pen and Pen/Pencil Writing Sequences"
The determination of pen/pen and pen/pencil writing sequences continues to present difficult challenges for the forensic document examiner. While a variety of methods have been proposed to aid in their decipherment, the light microscope remains the most useful tool. However, the document examiner must be fully acquainted with the microscopical characteristics delineating each sequence. In this paper, the microscopic characteristics of pen/pen and pen/pencil crossovers will be discussed in conjunction with an interesting case study that will illustrate several of the ideas presented.
"Comparison of Synthetic Fiber Types in Vacuum Debris from Different Households"
A common problem in criminalistics is to determine that one person, place or thing has been present in, or made contact with, another person, place or thing. For example, by examining trace evidence present on clothing, the criminalist seeks to establish that the wearer of the clothing was in a particular location from which the trace evidence on the clothing originated. Relying on Locard's Exchange Principle which states, in effect, that when two object comes into contact there will be a mutual exchange of material microscopic debris from that environment, and search the environment for trace evidence originating from objects suspected of having been in that environment. In some cases, some material that is unique to the environment, or the object, may have transferred and by establishing the unique characteristics of the transferred material an association between the environment and the object may be inferred. In general, however, the materials present in an environment are not unique to that environment, but are common materials that may be found in other environments.
One common type of evidence found in the environment, and easily transferred and carried away, are various types of plant, animal, and man-made fibers. In some cases, more than one type of fiber from an environment may be analytically indistinguishable from fibers found on the item suspected of having been in that environment. The evaluation of multiple fiber transfers depends both on the uniqueness of the individual fibers and the uniqueness of the combination of fiber types found. There is little data in the literature to establish the uniqueness of fiber combinations in particular environments. In this study, samples of debris were obtained from vacuum cleaners in a number of households. Pieces of clean cotton cloth were placed in bags with the vacuum debris and agitated until the clean cloth was covered with debris. Sticky tape (transparent fingerprint tape) was then used to recover the loose material adhering to the cloth pieces.
The tape lifts were then examined microscopically and fibers present were classified according to a previously developed classification scheme based on type (synthetic, animal, vegetable), color, crossection, and optical properties. Comparison of the combination of fibers found in the vacuum debris samples shows that the combinations are clearly distinguishable. Other studies have shown that most, but not necessarily all, randomly collected fibers from various sources can be distinguished by plane and polarized light and fluorescence microscopy. The presence of unique combinations of fibers in an environment suggests that time spent looking for and characterizing multiple fibers using quick light microscopy techniques might allow associations to be established based on the fiber combinations that are present.
"Forensic Hair Comparisons in the New Millennium"
I would like to celebrate the 50th Inter/Micro with a talk about one of the oldest trace evidence specimens, a specimen that illustrates the plight of the forensic microscopist as the 20th century comes to a close, but a specimen that still represents quintessential trace evidence for the new millennium. The rich history of forensic hair comparison from Hooke to Kirk (pre-Inter/Micro) is divided into epochs illustrating a stratigraphy of development. Unfortunately, for periods of time there were conspicuous lapses of discussion regarding the forensic hair comparison at professional meetings and in the scientific literature. This seems to be a consequence of the specialty struggling toward a way to automate the process. In every era, the process returned to more of a craft industry based on microscopy. Around the time of the U. S. bicentennial, the forensic sciences experienced an onslaught of pressures, both from within and without, calling for an upgrading of skills, improving education, and better performance. After a rejuvenation under the influence of the Atlanta Child Murders in the 1980's, hair and fiber evidence came alive again only to be smothered by the O.J. Simpson case in the 1990's. DNA blotted out all the light by taking away the experts, taking away the funding, and pushing forensic trace evidence en masse into the DNA Thermal Cycler. Nevertheless, I predict that forensic hair comparison will bloom again because hair remains a good marker of human individuality, a microscopic particle bearing a wealth of information and valuable forensic evidence. My prediction will come true if forensic hair comparison remains true to its science with standards for training a new generation of microscopists and for quality laboratory practices.
"Sequence of Intersecting Pen Strokes Using Scanning White Light Interference Microscopy"
A set of known intersected pen strokes was evaluated by scanning white light microscopy to determine pen stroke direction, pressure and sequence. Interference microscopy was used in the vertical scanning interference (VSI) mode to examine pen troughs formed by writing on paper. The primary use for this type of interference microscopy is surface metrology where the roughness of a surface is quantitatively determined and displayed in a variety of statistical formats. Each objective on the microscope contains an interferometer consisting of a reference mirror and a beamsplitter. Interference fringes are produced when light reflected off the reference mirror combines with light reflected off the sample surface. The objective head vertically scans down through focus-detecting interference fringes for each point on the sample surface.
Once the sample surface fringe information has been acquired, surface height differences can be displayed with a high degree of accuracy. Scanning white light interference microscopy, a non-contact non-destructive technique, requires sample preparation and two-dimensional and three-dimensional images are quickly acquired. Troughs in the paper surface are imaged where writing pen lines intersect revealing the effects of variable pen pressures and pen stroke sequences. Initial testing with known pen strokes and data obtained on this second blind set of pen strokes suggest that scanning white light microscopy is a useful technique for determining the sequence of intersecting pen strokes with similar ink colors on document evidence.
"Forensic Paint Analysis (Using All The Tools We Have)"
Forensic paint analysis has entered a new and challenging period with the advent of new, strict environmental and occupational health regulations. This fact is most evident in automotive paint systems that are tightly constrained, not only by these new regulations, but also by the extreme environmental exposure conditions, appearance and durability requirements that have always been a part of automotive paint selection criteria. The combination of demanding regulations and performance criteria have left the automotive industry with few paint systems to chose from and led to the use of just a few paint chemistries by several manufacturers.
Forensic scientists now face the task of trying to differentiate similar automotive paint systems, using very small amounts of material, collected under less than ideal conditions, from surfaces that may exhibit varied composition over short distances. Few other forensic comparisons are as complex. The comparative techniques used can include light, electron and fluorescence microscopy, visible, infrared and ultraviolet spectroscopy and x-ray spectrometry, pyrolytic gas chromatography, mass spectrometry and x-ray diffraction. The foregoing list makes no mention of the preparative methods that are a part of each technique.
A recent round robin (infrared spectroscopy) study of several black automotive paint systems (including primer, colored base and clear paint coats) presented an unexpected problem when one of the nine items in the study contained two samples. Which, if either, sample was the intended item? Were they two samples of the same paint system? If the samples were different, how? What constitutes "difference" in automotive infrared absorbance spectra from microscopic samples? Can any of the noted differences be supported by other techniques?
This presentation will show examples of the efforts that went into resolving the questions an unexpected sample presented in an otherwise straight-forward, controlled study of supposedly known materials.
"Identification and Differentiation of Baby Formulas Using PLM"
Theft, smuggling, and the illegal sale of baby formula on the black market in third world countries has become a problem in recent months. After these goods are stolen, they are usually repackaged or labeled falsely to facilitate the smuggling process. When this contraband is recovered by US Customs officials or other forensics personnel, the task at hand is to identify the contents of the containers. Presented here is a proposed method for analysis of these baby formula products, specifically in the powdered form, by using microscopical techniques. Additionally, an attempt to differentiate various formulations is considered.
"Microscopical Characterization of Suture Fibers"
Suture fibers are a group of fibers that may be encountered by fiber microscopists, especially the forensic fiber microscopist. Suture fibers are classified in to two broad categories: absorbable (loose their tensile strength within 2 to 3 months) and non-absorbable (retain their tensile strength longer than 2 to 3 months). Non-absorbable fibers include cotton, flax, silk, polyethylene, polypropylene, polyamide (nylon), polyester, polytetrafluoroethylene and stainless steel. Absorbable fibers include cat gut (collagen from sheep intestinal submucosa), reconstituted collagen, polyglycolide (PGA), polyglcolide-lactide random polymer (polyglactone), poly-p-dioxanone (polydioxanone), polyglycolide-trimethylene carbonate block copolymer (polyglyconate), polyglycolide-caprolactone) (poliglecapronrone), and glycolide-trimethylene carbonate block copolymer (glycomer). Little identification characteristics for suture fibers are available in literature for the fiber analyst, especially for the absorbable suture fibers.
The physical and optical properties as well as the FTIR were determined for 22 commercially available suture fibers. Twelve of the fibers characterized were absorbable suture fibers and 10 were non-absorbable fibers. The data generated from the study will be presented.
The field of Forensic Microarchaeology falls under the broader area of science in service to Archaeology. This field is diverse and new, and it offers both challenges, problems and interesting work for microscopists.
The field will be described and then illustrated with examples to include a Byzantine cemetery (4th to 6th Century CE), anchor ropes from the Dead Sea (3rd Century BCE), The Philistine city of Ekron in the Iron Age (8th Century BCE), and residue present on prehistoric stone tools.
"A Novel Use of a Stereomicroscope Transmitted Light Base for Image Contrast Enhancement"
When a new Leitz MZ-6 stereomicroscope unit with a ring light for reflected light was purchased with a transmitted light base, the original concept centered on using polarized light in the transmitted light mode. After several months evaluation, the polarized light technique was used rarely with most cases requiring the reflected light application. The white/black two-sided disk supplied with the unit was used and found to be occasionally inadequate. As case work progressed and photomicrographs were taken, realization that a contrasting background to the sample (other than black or white) would improve the appearance of the sample and assist in photomicrography.
Replacing the white/black disk with the clear glass plate supplied with the transmitted light base, instantly provided a variable contrast background. Using the frosted glass side of the substage mirror, a bright white background can be obtained. By rotating the substage frosted glass, varying degrees of brightness/darkness of the background can be observed.
By using clear glass colored filters on the frosted glass side of the substage mirror, different colored backgrounds can be obtained to enhance the contrast of the sample relative to the background.
"Microscopical Characterization of an Emulsion Explosive"
An emulsion explosive mixture is characterized by microscopical techniques to
help in future identification of the material or similar materials.
Microscopical examination of the material reveals a number of characteristics
that allow identification as a possible explosive
material. All of the key components of this particular Ammonium Nitrate/Fuel Oil (ANFO) explosive can be observed with the polarized light microscope and confirmed with microchemical tests. The oil emulsion, ammonium nitrate microspheres and aluminum fragments are recognizable microscopically. Visual observations with the microscope are also useful in distinguishing between slurry/water gel explosives and emulsion type explosives. Fresh emulsion explosives can be recognized by the presence of a fine emulsion (1-5 micrometer) and the near absence of birefringent crystals under polarized light. Slurry or gel type explosives are recognizable by the absence of the emulsion and presence of large (1-2 mm) birefringent ammonium nitrate crystals or prills.
"Analysis of Printing and Coating Defects"
When a large printing or coating run is performed, occasionally problems arise that are generally blamed on the paper substrate. We are then asked by the paper maker to investigate the cause. Many of these complaints have been examined using the light microscope and a variety of causes were found. The traditional causes can still be found in even the most modern of systems.
"Defect Structures in Some Insulted HMX Composites"
PBX 9501 is a plastic-bonded HMX-based explosive traditionally prepared by warm pressing and machining of granulated composite molding powders. It is used as a main charge to assemble critical nuclear weapons components, so it is important that we understand its stability against plausible conditions of thermal and mechanical insult in order to ensure their safety. We have insulted a suite of both PBX 9501 and pure HMX samples in purely mechanical (low strain-rate bend tests), purely thermal (burning and quenching), and complex thermo-mechanical (high strain-rate modified Steven, spigot gun tests) ways. The resulting surface structures are analyzed by scanning electron microscopy (SEM) and compared with underlying substrate structures shown in polarized light microscopy (PLM) of crossections. The defects induced by quasistatic bending include twins and cleavage of coarse grains and heterogeneously strained ligaments of binder, as previously described by J.E. Field and coworkers. Those introduced by burning and the conditions of high strain-rate insult imposed here are remarkably similar. These observations are described by the polymorphism of HMX, particularly by the regrowth of delta HMX from a transient melt.
"Recent Advances in Microfluidics"
A number of key developments from microelectronics and analytical chemistry have been recently combined to generate entirely new methods for sampling, moving, and analyzing microscopic quantities (< 0.1 µl) of liquids. Photolithography can be used to create injection ports, channels, and reaction chambers on glass and polymer surfaces to create a virtual "lab on a chip". These devices offer many of same potential benefits of miniaturization and low cost that have revolutionized the microelectronics industry. An introduction to this rapidly changing field, along with experiments using non-lithographic "chips" will be presented.
"You Be the Jury"
This experimental session is a one-hour interactive presentation in which the bare facts and essential trace evidence findings in a case will be briefly described to the audience. They will then be asked to try to determine the outcome of the case. All of the cases are true and have been adjudicated in a court of law. Let's see what happens when the audience becomes the jury.
" A Specialized Analytical Prodedure for Analysis of Roofing Cores for Asbestos"
The analysis of individual layers for roofing cores is often difficult due to the asphalt. The asphalt is soluble in refractive index liquids but the solution still obscures asbestos fibers.
The asphalt is removed from the roof felts and mastics by extraction with methylene chloride. The solvent removes the asphalt from the entire roof core so that each layer can be analyzed individually without interference. This process also allows the analysis of any fibers found in the roof mastics and their relative location in the core.
"Unresolved Problems in Asbestos Analysis"
Although analysis of materials and environmental samples for asbestos is
often considered to be a "mature" science, specific problems still exist which
give rise to analytical discrepancies and differences in interpretation.
Ambiguities of fiber identification or quantification
continue to occur as a result of the use of poorly-defined or inappropriate analytical methods, or because the nature of the fiber is such that it yields data capable of alternative interpretations.
Materials containing "fibrous talc", some sources of sepiolite, and chrysotile from the New Idria deposit in California all present analytical problems which continue to result in serious discrepancies between analysts and laboratories.
In analyses of lung tissues for asbestos, the results of which are often used in personal injury litigation to establish the nature and extent of asbestos exposure, different specimen preparation methods for quantitative transfer of inorganic particles from the lung tissue to an analytical specimen are in use by different laboratories. There is not even consensus on the type of microscope to be used for the analysis; some laboratories use transmission electron microscopy (TEM) to examine the specimens, and others use scanning electron microscopy (SEM).
In some circumstances, regulations have been written in such a way that
determination of compliance can be subjective, even when the analytical
procedures for asbestos identification are straightforward. Tremolite,
actinolite and anthophyllite can be identified by either optical microscopy or
by TEM. However, the regulations do not contain a method by which an
analyst can classify a single fiber unequivocally as asbestiform or non-asbestiform. Since the non-asbestiform varieties of these amphibole minerals are not regulated, the subjective opinion of the analyst is often the only basis on which materials containing these amphibole minerals are classified either as unregulated or as "asbestos-containing" and therefore regulated.
"Use of Electron Microscopy in the Study of Indoor Air Quality (IAQ) Samples"
As adjuncts to light microscopy, scanning electron microscope (SEM) and transmission electron microscopy (TEM) can provide useful information in the characterization of indoor air particles. This presentation will show how the SEM with X-ray energy dispersive spectroscopy (EDS) was useful in suggesting the source of airborne particles, such as mineral wool fibers thought to be causing itching problems in an office building. TEM has been used to characterize different types of soots where the ultimate particle size is less than 0.2 µm. Several different types of air sampling filters were examined as media for IAQ particle collection and examination. The standard filters used by EPA for gravimetric particulate determination (PM10) are made of glass fibers. These were found to be difficult to examine directly or to separate from particles. The standard OSHA filters used for nuisance dust determination were also found to be difficult to examine. The new EPA filters composed of Teflon used for fine particle determination (PM2.5) were also found to be difficult to use for microscopical examination. The potential to use the commercial Air-cell IAQ impaction collectors with electron microscopy techniques was examined.
"3-D Models of Mold Spores for Teaching Fungal Morphology"
We see and experience our world in three dimensions. It is easy to imagine and form a mental image of the third dimension from photographs of familiar things we are familiar with and routinely see in our daily lives. To conceptualize the third dimension of microscopic items while viewing them through the microscope, is often challenging, even to an experienced microscopist. To facilitate this mental transformation of a flat microscopic image to one that encompasses the third dimension, I created 3-D models of twenty fungal spores. Each spore, approximately 2000 times its actual size, shaped, and painted to resemble the appearance of fungal spores, represents several genera commonly encountered during indoor air quality investigations.
"Mold/Pollen Gel Stain for Teaching Fungal Morphology"
Hyaline fungal spores in air samples are difficult to observe and identify utilizing brightfield microscopy (1000X magnification), because the colorless unstained spores tend to blend into the background and may be easily overlooked. A special combination of Phenosafranin Glycerin Jelly and Lactophenol Cotton Blue stains assists the microscopist in observing hyaline fungal spores and pollen grains. The Mold/Pollen Gel stain colors many hyaline fungal spores and skin cells light blue, the exine of many pollen grains light pink, and most of the remaining pollen grains components, light green.
"Amber: Historic and Scientific Perspectives of an Extraordinary Natural Material"
Amber is an extraordinary material. It is certainly remarkable for its physical and chemical properties, including the manner and degree to which it preserves materials occluded within it. It is also remarkable for the role it has played in human history. Throughout, and even before, recorded history every society familiar with it has valued amber. It has been valued for its aesthetic qualities, for its properties as an artistic medium, and it has often been attributed with medicinal and even magical properties. Few other materials, and no other natural organic products, have inspired such beliefs or had such a profound role in human history. From Etruscan traders and Roman gladiators, to the excesses of the Teutonic Knights and the intrigue of stolen German treasures; amber has had, and continues to have, a prominent and often profound role in history. This presentation attempts to give an overview of both our current understanding of amber from a materials science point of view and the remarkable, often colorful, place of amber in the history, mythology and artistic heritage of the many cultures that have treasured it.
"A 1935 Biologist Look at the "New" Phase Contrast Microscope"
In 1935, Zernike presented the world with the Phase Contrast Microscope. This earned him the Nobel Prize (Physics) in 1953, and constituted the first real improvement in microscopy since Abbe's work in the 1860-1880's. Biologists were excited about the potentialities of this new method of viewing organisms. Using slides prepared in the 1930's, and microscopes of that time, versus a 1990's Phase Contrast microscope, a series of comparative photomicrographs will be shown.
"A Century of the Electron"
The electron was discovered by Sir Joseph J. Thompson in 1897, so it is appropriate to commemorate its discovery and the impact of electrons on microscopy. The early history of the electron, a beam of which is called a cathode ray, is presented with the development of electricity. Today, electronics is the biggest industry in the world and it continues to develop. Transmission electron microscopy came along in the 1930s, followed by electron probe microanalysis using any one of many signals from the electron-specimen interaction. In the 1950s, television was developed and the computer, both having a profound impact upon science and microscopy. The future of microscopy is briefly considered in terms of electronics.
"Frank Lloyd Wright's use of Beeswax Paint"
Wingspread, built in 1939 on Wind Point in Racine, Wisconsin, was designed by Frank Lloyd Wright as the home of the Johnson's Wax family. This was Wright's largest single-family residence and the last of his Prairie style houses.
An investigation and analysis of the original paints on the rough coat plaster walls at Wingspread confirm that Frank Lloyd Wright used a very unusual beeswax paint, with a palette limited to four colors. However, the choice of colors and the variation in their shades, along with the manner in which the paints were applied, created a unique decorative effect that clearly reflects Wright's artistic genius with color and unusual media.
"Analysis of Organic Materials from the Haifa Faisal Collection"
Fourier transform infrared microscopy (FTIR) was used in conjunction with polarized light microscopy, field emission scanning electron microscopy and gas chromatography/mass spectroscopy to identify several different types of corrosion and efflorescence found on various objects in the Haifa Faisal collection. The Haifa Faisal collection represents an interesting and varied group of Saudi Arabian traditional arts. The nomadic lifestyle of the Saudi peoples resulted in the use of a wide variety of materials they incorporated into their traditional crafts. These objects, some of which are made with more than one type of material, present many potential challenges to the conservator.
Several case studies will be presented where microanalysis was used to identify the corrosion and efflorescence that appeared on some of the wooden objects. Accurate identification of corrosion products is crucial to the determination of the best choice of treatments and allows the conservators and curators to make informed decisions about long term storage/display. Also, objects made of organic materials could be identified in order to more accurately catalogue the collection. This project illustrates how important microanalytical techniques can be in the conservation and study of ethnographic collections.
"The Biological Stain Commission"
Over the last 150 years histologists have developed beautiful ways of staining histological and pathological tissue sections to differentiate different types of tissue and different intracellular components. Many of the dyes used are made in tonnage quantities for textile dyeing, making the amounts used in biology insignificant to the manufacturers. The dyes are in most cases not single, pure chemical compounds, but varying mixtures of closely-related substances. Slight variations from batch to batch are of little significance to the major industrial users, but of great significance to biologists, where subtle color differences may be important diagnostically. The work of the Commission over the last 75 years in standardizing procedures and certifying stain lots for specific purposes is described.
"Robert Hooke's Micrographia (1665) for Thirty Bucks"
An original copy of Hooke's epoch-making book 'Micrographia' from Brian J Ford's library has been featured at Inter/Micro and attracted much interest. This book, which launched the science of microscopy, has now been digitized and re-published on CD-ROM (with an Introduction by BJF too). The facsimile is intended to bring the exact look of the book to an audience, at an affordable price. There will be opportunities for personal hand's-on experience for delegates during this year's meeting.
"A Two-Hour Demonstration of Useful Sample Preparation Tools and Techniques for Ultramicroanalysis"
Sample preparation and toolmaking techniques using a stereomicroscope, some microtools, supplies and substrates will be highlighted by video demonstrations of the sample handling techniques.
A number of industrial problems will be discussed, such as: extracting
defects from paint films or pill surfaces; isolating less than 10 µm particles
from CD disks; taking ink samples from a document; removing a fine precipitate
from a filter, metal or plastic surface; and checking solubilities or
determining melting points. These techniques can be applied to large samples as
well as to those no larger than a few nanograms. The video will show the
advantages of miniaturization of current sample preparation techniques. Examples
of actual tools and supplies that are used in the video will be available for