The general consensus has been that the shells of mollusks form outside of cells. Akin to bone formation in vertebrates, an organic matrix is secreted by cells and the inorganic material is deposited within this matrix in an organized way. Andrew Mount, A.P. (Hap) Wheeler, Rajesh Paradkar, and Dennis Snider have now found convincing evidence that blood cells (specifically a class of granulocytic hemocytes) may be directly involved in shell crystal production for oysters.

The Field Emission SEM was introduced to improve imaging resolution available with conventional SEMs with a tungsten source. Thermal assisted or Schottky Field Emission SEMs were introduced in s the nineties by a number of companies as a stable source to overcome the beam instability of the cold FESEMs introduced earlier. The Gemini® based Field Emission SEM launched by Zeiss 12 years ago has been designed from the beginning as a high stability FESEM with a relatively large multi-ported chamber. The drive to develop Gemini® technology was the need for a FESEM capable of ultra-high resolution performance over the entire accelerating voltage range that also possessed the flexibility needed for a wide range of analytical applications.

Traditionally a scanning probe microscope (SPM), such as the atomic force microscope (AFM), affords spectacular images of surfaces at the nanometer scale. With advanced developments in scanner design, probe manufacturing and force sensor technology it is now possible to make quantitative metrological measurements with an SPM. Quantitative metrological measurements that are possible include: a) dimensional measurements of micro/nano fabricated structures, b) surface texture of surfaces having RMS values of only a few angstroms, and c) measurements of the number of grains, and particles on a surface as well as grain and particle sizes, areas, volumes, and distributions.

Image quality of 'secondary electron imaging' has been an ongoing operational issue with the variable pressure range of scanning electron microscopes (VPSEM), including the extended pressure range environmental or SEM. A second question that has received considerable attention concerns charge cancellation on insulators in VPSEM with particular reference to effects of charging on x-ray microanalytical results.

An earlier article in Microscopy Today, "Rediscovery of Darkfield Dispersion Staining while Building a Universal Student Microscope," noted that the darkfield inserts were made for Peter Cooke (MICA, Chicago, IL) to be used to teach high resolution dispersion staining in his advanced microscopy classes using Olympus BH2 microscopes and the Olympus 1.25 NA Abbe condenser. Peter has asked whether there is a better condenser design that will reduce the time and effort needed to switch between brightfield and darkfield.

Since the publication of the use of a dicing saw for TEM sample preparation, several analytical labs have adopted this method as standard practice for site-specific cross section and plan view samples. In this article, we would like to provide additional practical details of these procedures, and describe several extensions, including useful notes on batch processing, preparing samples with an area of interest very close to the sample edge, and a Focused Ion Beam (FIB)-compatible sample holder. We present an unusual amount of detail in these processes to show some of the evolution of the method since its introduction and to allow others to easily reproduce these results.

The primary responsibility of the clinical electron microscopy laboratory is to produce, and deliver to the pathologist or clinician, high quality ultrastructural images of pathological specimens in a timely manner. In order to facilitate this process, medical EM labs are converting from traditional chemical processing of photographic film and paper to the acquisition and transmission of electron images by computer. Ideally the electron microscope would incorporate a digital camera in the column to collect the images, thus bypassing chemical processing of film and paper altogether. However, due mainly to the high cost of the in-column cameras, many labs continue to use film, but replace the time consuming enlarging/printing in the darkroom with digital techniques at the computer.

Image acquisition in a TEM requires the conversion of the electron image into a photon image and the acquisition of this photon image with an imaging device. There are two principal techniques to do so: a fiber-coupled camera and a lens-coupled camera. Both have advantages and disadvantages. Please be aware that we (Soft Imaging System Corp) produce both types of cameras. There are also two principle camera positions on a TEM, and the choice of position must be taken into account for any decision. The positions are: side-mount (camera mounted on 35mm port above the viewing chamber), and bottom-mount (also known as on-axis mount, camera mounted below the viewing chamber).

When a sixty thousand dollar microscope is used as a paint brush, neither science nor art are in trouble - but rather benefactors, witness to the fact that there can be "science in art" and "art in science."

Arguably, except for a very few kids, our high schools are churning out hamburger helper generations, the product of a defective educational philosophy that believes that self esteem is more important than inspiring a tough academic regimen that leads to the pursuit of a science-focused secondary and post secondary education. Horses drink water because they want to, not because they were led to it. Kids pursue science and the achievement of excellence not because it is available, but rather because somewhere along their early education experience someone inspired their interest and curiosity.

The increased emphasis on nano-structured materials is placing an ever increasing demand on sample preparation techniques to unveil such fine structure. Nano-structured fibers are even more difficult because of the ease with which these materials can smear even when prepared under liquid nitrogen (LN2) as shown (Figure 1). This is especially true for the islandin- the-sea structures where it is rather hard to reveal the island structures due to smearing. In the search for a possible solution, a sample preparation technique that has shown great results in other composite structures of different polymer blends was applied to these structures.

As you ease the bell jar back down onto its seat, past the evaporation fixture, it is quite easy to chip a $600 jar. Chipped bell jars are a perennial problem in EM labs. They degrade vacuum in evaporators resulting in lower quality films and ultimately shorten the life of the vacuum system. This note describes a new resin that I have used for repairing bell jar chips.

A common chip can be seen in Fig. 1. It was caused by crashing the bell jar into the evaporation fixture. The chip is less than 0.5mm deep. Beside it you can see another chip that will not be treated as it does not extend to the jar edge.

Because of the high cost of Polaroid film, many years ago we fitted our Hitachi S-450 scanning electron microscope with a 35 mm camera. At that time, we used a Pentax ME Super, which was totally manual and had to have the film advanced by a hand lever. This was an annoyance, but when we set up the system, Polaroid Type 55 film was about $2.00 per photo, and the cost of 35 mm spooled in our lab ran about $.10 per photo.

When we traded the Hitachi S-450 for the later Hitachi S-570, we moved the 35 mm system to this microscope. About 1999, when the Pentax ZX-50 with motorized film advance became available, we adapted it to the S-570, using the Pentax electric shutter release. The lens used with both of these cameras was an elderly 50 mm screw-mount Pentax Macro lens that focused well on the CRT of the SEM.