The atomic force microscope (AFM) has been used in many ways to extract information from biologic specimens. Now Gerry Leatherman, Edgar Durantini, Devens Gust, Tom Moore, Anna Moore, Simon Stone, Ziniu Zhou, Peter Rez, YangZhang Liu, and Stuart Lindsay have used conduction atomic force microscopy (CAFM) to demonstrate that a molecule of carotene can function as a molecular wire.

Leatherman et al., synthesized carotene and then examined the molecules with the scanning tunneling microscope (STM), They could image spots that averaged 2 nm in diameter, although the size of the spots varied widely due to the geometry of the probe tip. Interestingly, the number of spots increased with the concentration of carotene, but the average size of the spots did not change. This made it clear that they were able to image carotene molecules with the STM, and that the carotene did not form large aggregates.

In a criminal case, such as vehicle theft or vehicle hijacking, where a vehicle has been dismantled, the forensic scientist is many times faced with the problem of establishing the history of a specific auto body part. The normal method for doing this is by performing paint analysis. There are, however, a few shortcomings to paint analysis. In this paper another technique for determining the history of a body part is discussed, namely the comparison of surface replicas.

A significant percentage of technical experts who employ optical microscopes have had little or no formal training in optical microscope basics. Some, typically, were required to use microscopes during their technical education but, in general, microscope terminology and technology was a sideline to their major training. As a result, many useful basic microscope technical details were not learned because they were not necessary to accomplish what was needed in order to survive their major class work. At Florida State University, we try to make the [earning of microscope technology an inherent part of the students training. An important part of this training is this compendium of 50 of the most frequently asked questions about Optical Microscopy.

Traditionally the field of microscopy has centered on the creation of highly magnified images of things too small to be seen with the eye alone. This was certainly the case with scanning probe microscopy, which burst on to the scene some 15 years ago with dramatic images of individual atoms. We are visual beings and the rapid acceptance of SPM followed directly from its ability to represent physical interactions in an intuitive image format. However, much of the vaiue of SPM today derives from its ability detect and measure a wide variety of specific interactions between its scanning probe and the sample. As the technology continues to mature, emphasis is shifting from its ability to display these signals as images to its ability to quantify and measure them.

The increasing availability of the user-friendly black box can present an increased probability of characterization errors. The uninformed choice (e.g., any SEM will see this) or dependence on one instrument can also lead to erroneous results. Failure to understand the limits and advantages of a particular instrument and bias through assumption or desired result can be equally deceptive.

In the example presented here, the objectives are to determine primary particle size and to identify the impurities in a specimen. We will look at the data produced by several instruments and discuss the ways each technology can support or mislead the analysts.

Images were acquired optically by secondary electron (SE), x-ray dot maps and back scattering electrons (BSE). The elemental analysis techniques used were Energy Dispersive Spectrometry (EDS), Wavelength Dispersive Spectrometry (WDS) and Powder x-ray diffractometry (PXD).

Field emission SEM (FESEM) and optical images are used.

All insects have an exoskeleton made of chitin, which is a protein that is hard and impervious to moisture. To enable processing reagents to more effectively enter the body cavity, a small slit in the abdomen can be made. For very small insects, such as the fruit fly, Drosophila, micro dissecting tools can be made from commonly found items such as insulated electrical wire, double edged razor blades and wood applicator sticks.

The genus Cryptantha Lehm ex G. Don section Oreocarya (E. Greene) Payson of the family Boraginaceae presents some problems to botanists, both professional and amateur, in the keying and identification of species. The genus contains approximately 150 species, the section about 60 perennial and biennial herbs located generally in western North America. Identification has presented some taxonomic difficulty due to the variability and lack of distinctive vegetative characters. Botanists have turned to the nutlet (fruit) and flower morphology to aid in identification for precise specific differentiation. In the past, 10X magnification and a decent botanical illustrator were required to provide the illustrations necessary to assist in this identification. We are in the process of collecting micrographs of nutlets (dorsal, sagital, and ventral views) and developing a webpage containing these micrographs along with descriptions of their morphological variations.

The semiconductor industry is committed to introducing copper interconnects in place of aluminum for the latest generation of semiconductor devices. With its greater current carrying capacity, the use of copper should enable further reductions in device geometry, power consumption and heat generation, and lead to higher performance and longer battery life in portable devices.

Grain orientations, crystal log raphic ‘texture’ trends and boundary types are crucial in determining properties such as electrical resistively, strength and corrosion resistance. These parameters may be implicated both in the performance of the device and in failure mechanisms, which are of great importance in determining reliability.

Our work demonstrates that high-resolution electron backscatter diffraction (EBSD) is now both possible and routinely achievable using both hot and cold field emission gun scanning electron microscopes (FEGSEMs). Our results demonstrate that EBSD can be successfully used to map grain orientation and to reveal and classify grain boundaries for this application.

Often during light and fluorescent microscopy, one wishes to observe samples of cells (e.g., yeast) grown in liquid culture. This is sometimes difficult as the cells can move around under the coverslip and a wet mount can dry out, killing the cells. Protocols in which the cells are resuspended in molten agarose results in cells that are in many different focal planes and often stressed by the high temperature of the molten agarose. This protocol describes a method of depositing small pads of growth media containing agarose onto slides, which eliminates these problems. Choice of growth media depends upon both the growth requirements of the cells and the requirements of the microscopy method. For example, yeast synthetic media works better for fluorescent microscopy than yeast rich media, because the yeast extract in rich media is autofluorescent in the green (fluorescein/GFP) channel.

Poorly conducting specimens can be examined without coating by using a variable pressure SEM. However, many labs may only have a high vacuum SEM, or for other reasons, choose a high vacuum mode. In order to examine insulating specimens in a high vacuum SEM (using operating conditions conducive to BSE and X-ray analysis) specimens must be coated with a conductive thin film.

The perspective of this article is from a materials point of view, but the principles remain the same for biological examinations requiring similar information.

Back Scattered Electron (BSE) image contrast is primarily a function of the average atomic number of an imaged area. This is particularly true for polished specimens where there is no topography to contribute to contrast. The BSE coefficient is the ratio of back scattered electrons to incident (beam) electrons.

With today's requirements for chemicals and reagents in research and clinical laboratory environments, questions often arise concerning expiration dating. Why are not all chemicals and reagents expiration dated by the manufacturer when they are made? How should expiration of chemicals and reagents not dated by the manufacturer be determined? How would a laboratory establish expiration of solutions and reagents prepared in-house?

To assure good manufacturing practices, many manufacturers comply with guidelines set for them by agencies such as the International Organization for Standardization (ISO) and are inspected by ISO auditors. Some manufacturers are required to comply with the Food and Drug Administration (FDA.) These manufacturers are known as GMP facilities (good manufacturing practices) and are assessed by FDA inspectors. Like regulatory agencies who govern clinical sites, ISO and FDA require manufacturers to establish uniform quality systems for product testing and certification.

This article describes a simple, economical modification of the standard stage insert used on the Nikon TMD, Diaphot and E800 models of inverted microscopes to support slide securely without lateral motion or sample compression. The central portion of the stage on these popular microscopes consists of a removable insert that provides sample support and demarks of the imaging area. The insert may be replaced with holders for a variety of culture chambers and other specialized sample supports. This unique design contributes to the adaptability of these microscopes for a wide range of imaging applications such as confocal microscopy, calcium imaging and electrophysiology.

The standard insert is actually constructed of two pieces, an outer ring and a central plate (Figure 1A). The central plate is removed from the modified ring, which is then used in the inverted position (Figures 1B, 3, 4).

Interplanetary dust particles (IDPs) comprise an important source of extraterrestrial materials available for study of our solar system and originate from either the asteroid belt or from short period comets. IDPs from cometary sources are particularly important as they constitute the only physical samples of comets available; all known meteorites are derived from the asteroids, the Moon or Mars. By measuring the densities of IDPs and using an appropriate atmospheric entry heating model, it is possible to determine whether an individual IDP has been derived from an asteraidal or cometary source region. Calculating the density of an IDP requires knowledge of both its mass and volume, which can be determined by using a combination of secondary and transmission electron microscopy techniques. We have developed methods to measure both of these parameters and thus routinely measure densities for individual IDPS in the size range of 5-15 μm.

With the advent of Mohs surgery in the dermatology clinics, making sure the margins are clear of any cancer is of the utmost importance to both patient and dermatopathologist. While the patient is stiil in the surgery suite, immunohistochemistry staining can be done in the laboratory microwave (Pelco microwave with waiter load cooler wattage controller arid temperature probe). The immunohistochemistry procedure takes only 25-30 minutes as compared to the more conventional methods that take 2 hours or more.

The microwave needs to be checked for hot spots using the Pelco #36140 microwave bulb array. Make sure the area in which you are going to put your slides has no hot spots, indicated by no illuminating bulbs. Using a Sigma Diagnostics #H6644 Humid Chamber; place a paper towel in the bottom of the chamber and fill with 1/4 inch of water.

Small tissues are always difficult to work with. The limited size often leads to many technical problems. In spite of the care normally given to a specimen, the unthinkable can happen. A block may be cut through, slides may be broken, and sections may fall off. When this type of tragedy occurs, the creativity and technical abilities of a histology technician are often tested.

An example of this occurred when a technician was cutting a prostate biopsy. Two slides were taken, with two sections on each. The slides were taken, with two sections on each. The slides were stained with hematoxylin and eosin (H&E), and coverslipped with a Tissue Tek automatic coverslipper. This coverslipper uses a plastic film, which causes the film to adhere to the slide with xylene. The slides were then given to the pathologist who then requested an immunohistochemical (IHC) test to be performed. In the process, the specimen was exhausted.