Atomic Force Microscopes (AFM) can measure the force between a surface and the tip of a cantilever as a junction of separation with great precision. For example, van der Waals type forces and electrostatic repulsive forces can easily be measured in aqueous solutions using an AFM. The complex, pyramidal shape of the typical AFM cantilever is, however, not well suited for quantitative measurements. It is thus desirable to attach particles of known geometry (usually spheres) to the tip of a cantilever.

Start with a handbook of chemistry and physics, In the tables of physical constants will be listed the metals solubilities in various acids. Pick an appropriate acid, and as a first try use 10% acid in methanol (a good electrical conductor). Ethanol is less conductive and more viscous than methanol. Always check chemical safety before starting. Never mix nitric acid with ethanol, for example; it explodes above a 5% concentration. Chill the solvent to at least 0° C before adding acid.

Service contract expenses constitute a large proportion of many EM laboratory budgets each year and managers, under constant pressure to reduce costs, no longer look at the expense as sacred. Increasingly, microscopists are faced with finding alternatives to the full service contracts they enjoyed so long. I facilitated a discussion group at the Microscopy & Microanalysis '97 meeting held recently in Cleveland entitled "EM Maintenance: Can you do it yourself?" The audience of 50 represented microscopists from industry, academic and government facilities with a common interest - learning how to sensibly reduce service contract costs. In this article, I will offer my perspective on the subject and relate issues raised by the audience.

I would not, repeat *not*, recommend fixing any virus sample before attaching it to the grid. If you are concerned with pathogenicity, you can fix it after allowing it to adhere to the grid, then wash with water and stain, or you can UV irradiate both sides of the grid after staining. For speed in reporting clinical results (we do almost 1000/year), we look at negative stains of potentially infectious material without fixing by keeping a separate specimen holder for "dirty" grids and another for nonpathogenic material such as sections. The grids are then UV irradiated before storage,

The accuracy and precision of the quantitative measurements made with various types of scanning probe microscopes (SPMs) can be limited by instrumentation error. The piezoelectric scanners that are utilized in SPMs control either the motion of the cantilever probe with respect to a stationary sample or the motion of the sample with respect to a stationary probe. While these scanners offer many advantageous characteristics that are critical to the performance of SPMs, they also exhibit several behaviors, e.g., hysteresis and creep, that introduce uncertainties in measurements. Also, the nonlinearities associated with the photodiode used in the optical lever detection system can detract from the accuracy of measurements

Instructions are given as follows for making five aqueous mounting media: glycerol jelly, buffered glycerol with anti-fade, fructose syrup, Apathy's gum-syrup, and a polyvinylpyrrolidone medium whose composition can be varied to suit the user's needs, For each, hints are given on usage and the preservation of the coverslipped preparations. Media made in the laboratory are cheaper than commercial aqueous mountants, and do not contain any secret ingredients.

Ready or not, digital imaging in the microscope lab Is here to stay. While I am one of those fogies who insist that digital images are nowhere near as good as photographic prints, I've also bowed to the inevitable, and am beginning to find ways to assist the clients in our multi-user facility with their digital imaging needs, We can acquire digital images from our FESEM, from our light microscope with a CCD, and from a flatbed scanner. Clients use their images for image analysis, transport to others scientists via the Internet or World Wide Web, for reports, slides, overhead transparencies, and publication, Generally, these images need to be manipulated for use, just as one would manipulate a photographic print to correct any deficiencies in exposure or area of view. Adobe PhotoShop is the software of choice for image adjustment, accounting for more than 80% of the digital image-editing software market.