In antiquity men and women consumed more labor to produce products from fiber bearing plants and animals than any other activity. Today the manmade fiber industry has reached dazzling heights frying to improve on the quality of natural fibers like wool, cotton, and asbestos and at the same time trying to offer the product at a better price. The identification of the tiny textile fiber fragments which cover our clothes and floors and contaminate our manufactured products illustrates how light microscopy can help improve the work environment, keep our products clean, and solve the most serious crimes. The consulting microscopist sees fibers as penultimately a problem of materials identification and finally as part of an intriguing mystery. In other words, from an archaeologist's point of view, fabric analysis always reveals something of the weaver in the same way as a forensic scientist learns something of the criminal through identification of extraneous fibers on the victim's clothing.

The electron microscope facility at the Lineberger Comprehensive Cancer Center (LCCC), at the University of North Carolina, is a world leader in the analysis and visualization of DNA- and RNA-protein complexes. Established by Dr. Jack Griffith in 1978, the facility houses the only laboratory in the U.S. specifically dedicated to visualizing DNA- and RNA-protein interactions and is frequently called upon by research institutions and organizations to provide breakthrough scientific findings. For instance, Dr. Griffith, in collaboration with Dr. Paul Englund at John Hopkins University, was the first to visualize DNA molecules with unusual curvatures; and, working with Dr. Mark Ptashne and Dr. Tom Maniatis at Harvard, was the first to visualize the looping of DNA and splicesomes. Presently, the lab is working with Nobel Prize winner Dr. Arthur Kornberg at Stanford University to understand how DNA replicates.

According to Dr. Griffith, LCCC's electron microscopy system is part of a unique scientific approach to studying DNA- and RNA-protein complexes. The approach integrates electron microscopy with conventional molecular biologic and biochemical research methods.

People who have faced imminent death and survived report visions of their entire lives passing before their eyes. My experience at the recent 50th anniversary meeting of the Electron Microscopy Society of America was similar. In a matter of hours I saw a vision of the entire half-century history of electron microscopy. It was exhilarating.

I was an invited guest among the handful of surviving charter members. Attention was lavished on us and we were treated with TLC (the nursing profession's abbreviation for tender loving care). We recounted our experiences and had an opportunity to meet old friends and colleagues whom we had not seen in years. Most significant, however, were the formal presentations that showed the enormous growth of the field, both in depth and breadth.

I've been selling high tech products for about 20 years and I've never quite gotten over the fear of the phrase: “I'd like to go to the plant for a demo.”

As many of us have said in the past, there's no such thing as a good demo, only one which didn't disintegrate beyond all recognition. Every salesperson I know has his or her favorite stories of incredible happenings when the “Proximity Effect” takes over. (For the unknowing, the Proximity Effect states that the more closely the customer approaches a demo instrument, the more likely it is to self-destruct.)

My most memorable demo occurred when I was working with a French company selling semiconductor manufacturing equipment, I arrived with customers from the States and the first morning we were standing outside the demo lab passing the time until we were given the all clear from the instrument technician. As we conversed, an acrid odor permeated the lobby and the lights in the demo lab seemed to dim a bit. The odor became overpowering.

Oil contamination in SEMs is a common problem. It manifests itself as dark spots and carton buildup in low KV scans and oil condensation on EDX detector windows. While one of the most common sources of this contamination is oil backstreamed from the roughing pump, other sources include pump oils, lubricants, seals, fingerprints, and the samples themselves. Depending upon severity, this effect ranges from a minor irritation to a very major problem.

Historical solutions to this problem have included turbomolecular pumps (TMP), cryopumps, drag pumps, traps, better pump oils, cooler running roughing pumps, double diffusion pumps and fractionating diffusion pumps. Many of these solutions have proved to be costly, require much maintenance and/or have not been very effective.

An interesting sidelight of building our own 3″ diffusion pumps is that as we built ever larger vacuum equipment, larger pumps were required. Motivated by our success with the 3″ pump, we gradually built a series of larger pumps going up one size at a time to 10″ diameter.

Critical point drying was invented by Tom Anderson and described in his fine paper in 1952. He was a bit ahead of his time as the widespread use of the technique was not until the arrival of the SEM in about 1970.

I became involved in critical point drying when Dr. Gennaro of New York University asked if I could make him a unit.. He sent me a copy of Tom's original paper and we visited Tom's lab for a demonstration.

With Tom's dryer, the chamber opening and closing involved a high pressure threaded seal. Fortunately, he had working with him a man big enough to be a NHL defensive end who manhandled a three foot wrench to seal and unseal the chamber.

Over the years, we've seen major developments in electron source technologies in response to the demands for better performance. This article presents a brief overview of the cathode technologies in use today.

Two types of electron sources are used in commercially available scanning electron microscopes (SEMs), transmission electron microscopes (TEMs), scanning Auger microprobes, and electron beam lithography systems: thermionic and field emission electron cathodes. Thermionic cathodes reiease electrons from the cathode material when they are heated while field emission cathodes rely on a high electric field to draw electrons from the cathode material.