The living human eye is in constant motion. The cornea, which is the transparent front surface of the eyeball, is a formidable specimen for microscopy. How can we use a microscope to obtain sufficient contrast in order to observe cellular and subcellular details on a moving, transparent specimen? Although the normal human cornea is free of blood vessels, there are many nerves within the 500 μm thickness of this tissue. How can we observe these nerves in the living human eye?

To accomplish these aims, use a new real-time, scanning slit confocal microscope that was developed by Dr. A. Thaer for imaging the in vivo human cornea. The optical design of the real-time, scanning slit confocal microscope is shown as follows in Figure 1. The confocal microscope is a modification of the real-time, scanning slit confocal microscope based on an oscillating too-sided mirror (bi-lateral scanning) which was designed and first constructed in 1969 by G. M. Svishchev in Lenningrad.

Microscopes are known for demonstrating structure, but there have been many examples of how this is changing. A novel use of the atomic force microscope (AFM) by Manfred Radmacher, Monika Fritz, Helen Hansma, and Paul Hansma at the University of California, Santa Barbara, has extended the versatility of this instrument even further. They demonstrated a conformational change in a molecule that happened in a fraction of a second.

Radmacher et al. pointed out that enzymes perform their biologic function by undergoing a conformational change and that this change is within the spatial and temporal resolving capabilities of the AFM. They set out to prove this by lowering the tip of the AFM onto lysozyme, a molecule that is roughly egg-shaped, measuring about 4.5 nm by 3 nm by 3 nm. Using the tapping mode in liquid, they found that single molecules exhibited a spike-like height fluctation when in the presence of a suitable substrate.

EDS analysis of samples in a SEM or TEM are usually portrayed as a very simple process; just image your specimen, turn on the x-ray analyzer and all will be revealed about the chemistry of your sample. Unfortunately, that approach can be very misleading at best, and disastrous at worst. The analyst should get used to preparing himself for EDS x-ray analysis just like he or she does for any other process. A set of preparation steps should be followed until they become an unconscious method to be used before accepting the information coming from the EOS x-ray spectrum. After proper basic preparation, interpretation of the results and the selection of operating parameters is still very important due to the detailed nature of the specimen.

Preparation: The most basic need is for the EDS system to be calibrated. This can be a difficult or simple task depending on the age of the system.

Scanning acoustical microscopy has found a very comfortable niche in the area of non-destructive evaluation, testing and imaging. But the field need not be limited by such a narrow applications area.

In this article, a general review of current and possible applications will be conducted including archaeological conservation and evaluation. Part III of this series will deal exclusively with biomedical applications.

Since acoustical waves can penetrate a specimen, optically opaque materials can be visualized and more fully examined. Depending on the resolution required, a compromise needs to be achieved before a specimen can be imaged. Recall from Part I of this series, the higher the frequency, the better the resolution, but the depth of penetration is less. In many applications, it is not always necessary to achieve a high degree of resolution, it is more interesting to locate and identify internal structures. Acoustical microscopy is meant to be a complementary form of observation not necessarily a standalone modality.

A quiet report from an international work shop, this fall in London on World Ecology, points out how primitive our knowledge of basic soil science really is. It also records the determination of the participants to bring out the need to study soil in relation to maintaining biodiversity because of man's rapid destruction of global habitat and the inability for soil to recover without it's natural canopy of plant and animal life. It is further pointed out that we have to quickly learn how to reclaim soil, perhaps by artificial means, after insult. The programs they envision will create exciting professional opportunities both for career change and for students over a broad spectrum from basic research to applied engineering. The land fill crises has further underscored the need to find ways to return sewage sludge and other organic waste to useful crop production.