Established Laboratory Procedures Research Articles

A Videotape Editing System for Film Post-Production

For more than 25 years, attempts have been made to make use of videotape in editing of motion-picture film. One of the major obstacles has been the differences in frame rates between videotape and motion pictures. A new system has been developed that carries out the necessary frame-rate conversions with only a few minor changes to established laboratory procedures. Color positive or negative film material can be transferred to a videocassette work print. The software is designed to edit to 2-in or 1-in videotape for a television release, or to conform the film directly after the off-line editing is completed.

Experimental Lead Poisoning of Canada Geese

Canada geese (Branta canadensis) were experimentally exposed to known amounts of lead. The course of the lead and of the disease in geese was followed, utilizing established laboratory procedures. Gross signs of lead poisoning first appeared 5-7 days following ingestion. The length of time until signs of disease or death occurred was related to the amount of lead ingested. Twenty-five or more pellets resulted in death within 10 days, while 10 or fewer pellets permitted survival as long as 72 days. Ingestion of large numbers of pellets resulted in a rapid increase of lead levels in the blood, acute poisoning, and early death. Ingestion of fewer pellets resulted in a slower increase of lead in the blood, chronic poisoning, and longer survival, with more typical lead poisoning signs and pathology. Lead pellets appeared to erode at a constant rate regardless of the number in the gizzard. The largest lead pellet volume (66 percent) was eroded within the first 3 days after exposure, and it took approximately 45 days for the remaining volume to disappear. Normal lead levels of blood for Canada geese were found to be 0.018-0.037 mg/100 g blood. The lead levels of blood of lead-poisoned geese lesions asmore » well as histological changes are described. High lead levels in blood and liver tissue, significance and effect of lead poisoning on the fecundity of geese are discussed. 21 references, 3 figures, 2 tables.« less

An Apparatus for Grinding Bacteria at Low Temperatures

The disrupting of bacteria by grinding in mills is a well established laboratory procedure, for which various forms of apparatus have been devised. The long grinding required to break most of the bacteria introduced into an ordinary mill changes the material so that some of the immunologically detectable components are no longer present, or at least not identifiable. In order to take advantage of the brittleness of cells at low temperature, Macfadyen and Rowland used a grinding apparatus that was immersed in liquid air. Johlin and Avery constructed a heavy steel cylinder in which a moist bacterial suspension was frozen with CO2 ice; a tightly fitting plunger was introduced and struck 25 times with an 8 lb. hammer. These authors presented data indicating that this was a very efficient method of rupturing bacteria and obtaining the intracellular contents. For extracting tissues, a somewhat similar apparatus devised by Graeser, Ginsberg, and Friedemann was used by Fox to study the concentration of antibodies in tissues. Recently Mudd, Shaw, Czarnetsky and Flosdorf have devised an apparatus for disrupting bacteria at low temperatures after desiccation by the lyophil process. The grinding chamber consists of a hollow monel metal disc, milled out in such a manner that 2 large stainless steel balls 1½ inches in diameter fit accurately into the hollow. The bacteria are placed in this mill, frozen and dried by attaching it, with airtight connections, to a condenser which is immersed in a low-temperature freezing bath. Following the drying, the mill is rotated in a similar bath of CO2 ice and methyl cellosolve. At least 80% of the bacteria are completely disintegrated within a short time.

Synthetic Rubber. Its Industrial Production in the U. S. S. R.

Abstract The subject of synthetic rubber has not been neglected in the literature. However, all the publications, including those of Harries or some of the work of Dubosc and Luttringer or even the less complete works such as articles by Jacobs and by Whitby and Katz, contain systematic discussions of the various possibilities of synthesizing rubber, but these deal only with established laboratory procedures, which are for the most part theoretical for the very reason that they have been merely abstract researches and have not been applied on an industrial scale. It should, however, be mentioned that the recent publications of Carothers and his collaborators are not of this character, and Gottlob, who described the great efforts in the Beyer and Co. plant at Leverkusen where 200 tons per month of synthetic rubber were produced during the war, should likewise not be overlooked. Nevertheless a description of this latter process is not of much practical value, because it deals with a process which was abandoned a long time ago. As far as any interest today in the industrial synthesis of rubber is concerned, there is only the work being carried out in U. S. S. R. The author would refer economists and rubber technologists who may be interested in the details to his earlier article, and the purpose of the present article is limited to a detailed survey of the chemical process as applied in the U. S. S. R., leaving out of consideration an analysis of the reasons why it has been considered necessary in the U. S. S. R. to carry out this undertaking, and why ethyl alcohol has been adopted as a raw material for the synthesis of the new rubber, and leaving out of consideration all the statistics of the development of this industry and also technical information for the use of this new substance in rubber factories.