material throughout the volume in which the radiation was absorbed. Chemical solvents are used to selec tively dissolve away either the ex posed or unexposed portions. With ablative photodecomposition, how ever, removal of material is a direct consequence of the laser irradiation. Hence, no development with chemi cal solvents is necessary. Medical applications such as sur gery have used lasers mainly as sources of intense visible and infra red radiation that lead to burning of organic material. Ultraviolet radiation, however, even at low intensity, causes decomposition through electronic excitation and subsequent breaking of chemical bonds and polymer chains without heating effects. Such reactions are particularly efficient for far-ultra violet radiation. IBM work with cartilage tissue and hair has demonstrated that with repeated pulsing of the excimer la ser at intensities above the thresh old for ablation, considerable thick nesses of biological material can be removed in a relatively short time. In all cases, the irradiation resulted in exceptionally clean removal of material, compared with results us ing conventional laser techniques. The researchers haven't yet deter mined whether there is any effect on the underlying cell structure. G
Hazardous chemicals transport policy urged The Department of Transportation should take a much more vigorous lead in developing a policy that en sures the safe transport of hazard ous materials by rail and on the highways, recommends a National Research Council committee that has been studying the issue since 1975. Although the safety record for transportation of hazardous materi als in the U.S. has been a remark ably good one, the possibility al ways exists for a major transporta tion disaster, the committee says. The efforts of various governmen tal bodies and of shippers and trans porters to prevent such incidents and to fight them when they occur are badly in need of coordination
Chemical spills such as this one of 20,000 gal of nitric acid last April in Denver need better coordination by a single, lead agency. Currently, there is no agreed-upon statement of purpose among these various groups nor is there any clear time table or budget for solving the prob lems that exist in this area. Some 4 billion tons of hazardous substances—mostly gasoline—are transported by rail or on highways in the U.S. each year, the commit tee notes, although one of the cur rent problems is that statistics on shipments and accidents are poor. Best estimates suggest that about 16,000 spills occur annually, result ing in about 600 injuries, 20 deaths, and some $10 million in property damage. One of DOT's first tasks should be to form an advisory panel drawn from experts in the private sector as well as from state and local govern ments to help formulate national goals for improving hazardous ma terials transportation safety, the com mittee says. The panel also could advise the department on uniform training procedures for the groups that respond to transportation emer gencies and on ways to simplify and standardize existing regulations that govern the transport of hazard ous materials. If necessary, federal funds should be used to sponsor research on transportation safety problems and development of train ing programs.
The report grew out of a 1981 workshop sponsored by the Nation al Research Council to develop strategies to deal with problems in transporting hazardous materials. It was not requested by Congress or by any of the federal departments, and its reception by these bodies is uncertain. Some of its recommenda tions, such as streamlining federal regulation of hazardous materials transport, are in keeping with the tenor of the Reagan Administration. Others clearly are not, including the recommendation to expand the fed eral role in improving transporta tion safety. Copies of the report, "Transporta tion of Hazardous Materials: Toward a National Strategy," are available for $8.00 from the Transportation Research Board, National Research Council, 2101 Constitution Ave., N.W., Washington, D.C. 20418. D
Study proposes pruning high school curricula "Chemistry may have to be dropped as a separate subject in order that biology and physics can be taught well," suggests a study of U.S. high schools to be published later this year. "The world history course will cover fewer centuries," says the study, "the mathematics sequence will not get to calculus; the biology course will no longer include some phyla. We will be required to let go of many cherished sectors of the curriculum in our pursuit of the aphorism 'Less is more/ " These proposed measures to prune high school curricula are among those designed to educate students more deeply in subjects rather than simply cover a lot of ground. The study was sponsored by the Nation al Association of Secondary School Principals, Reston, Va., and the Na tional Association of Independent Schools, Boston. Study chairman Theodore R. Sizer, former principal of Phillips Academy, Andover, Mass., and former dean of the Harvard Graduate School of Educa tion, summarized the report in the June Phi Delta Καργαη, a profession al educators' magazine. June 13, 1983 C&EN
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