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Ignore but keep We are now wind ing up our 40th year in the micro film systems busi ness. To celebrate we lure the eye to the KODAK KOM-90 Microfilmer. In stead of microfilm ing papers of vari ous kinds, it takes magnetic tape from a computer and transcribes the in formation content to microfilm at the rate of 90,000 visible characters per sec ond. Wide choice is provided in format, spacing, character
fonts, and special characters. This permits entry to the human mind via the human eye, should any human mind ever be interested enough to look up something in the data. It saves paper, space to store the paper, and massive frustration in wading through the paper. Tell the machine which of three types of retrieval index to put on. A fourth is offered op tionally. Interchangeable overlays can superimpose your charts, grids, or other graphics on the displayed information. Thus we have labored mightily to make it convenient to ignore practically everything a computer puts out and yet keep every bit of it. A faint smile at this achievement is less likely from "business" computer users than from the "scien tific" type. On the other hand, in case your scientific endeavor should call for just this convenience, the Business Systems Division of Eastman Kodak Company, Rochester, N.Y. 14650 wants to find you.
The old ternary diagram Ink is largely ignored. You are looking at it right now and ignoring it. You have to be an ink manufacturer, though, to have that thought bother you. Ink perhaps should be ignored but not the problems of making it right. So we work with inkmakers on new cellulose esters we hope they will find useful as ingredients. Digging in at new spots on the old ternary diagrams seems to be no longer as attractive a pursuit among other polymer producers as it remains with us. In the past four years we have brought out for the benefit of ink manufacturers and other specialists one new cellulose acetate, five new cellulose acetate butyrates, and two new cellulose acetate propionates. One of the latter, at a place on the ternary diagram where solubility in alcohol prevails, is still at that stage where, if you phoned in an order for a truckload of alcohol-soluble propionate ("ASP") tomorrow morning, there would be some sudden throat-clearing at our end of the line. Ternary diagrams, the graffiti of the cellulose ester art, depict the range of possibility when either acetyl and butyryl
or acetyl and propionyl groups replace some or all of the hydroxyls that a β-glucose unit of cellulose carries. // a need to know more is felt, ask Eastman Chemical Prod ucts, Inc., Kingsport, Tenn. 37662 (Subsidiary of Eastman Kodak Company).
Boosting contrast in electron micrography Those who have gone into electron micrography with a sound understanding of the behavior of the photographic emulsion know all about the classic H & D curve of density vs. log exposure with its straight-line portion, its toe, and its shoul der. They know that the way to raise contrast is to increase development, which pivots the curve upward to a higher ξ| angle. Forget that part. Hurter and Driffield weren't exposing Exposure Increase to 5Q-KeV electrons. T h e curve that concerns electron micrographers has this shape:
Gaining contrast by exposure increase is the best way to gain contrast—if the specimen will stand it—because, while contrast rises linearly with exposure, noise in the electron image rises only as the square root of exposure. Other ways of boosting contrast, such as more development or a contrastier printing paper, don't help the signal-to-noise ratio. Try not to be bothered if the negative is darker than you would choose for viewing on the illuminator, as long as maximum density does not exceed 2.5. It may take a little more printing exposure, but the added information content may be worth it. If you have too many negatives to print and want to step up your production rate, see your dealer about the KODAK EKTAMATIC Processor, Model 214-K.
LOG EXPOSURE (Electrons/^2)
C&EN
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