A study conducted by high school advanced bacteriology students appears to confirm the hypothesis that the incremental administration of antibiotics on several species of bacteria (Escherichia coli, Staphylococcus epidermis, Bacillus sublitus, Bacillus megaterium) will allow for the development of antibiotic-resistant strains. (PEB)

Describes sensitive and specific methods used to monitor tetrachlorodibenzodioxins and tetrachlorodibenzofurans. The procedures are suitable for detecting and quantifying these substances at the parts-per-trillion levels in complex environmental and biological samples. (Author/JN)

Discusses the nature and applications of mass-selective laser photoionization. The ionization can be done with a single intense laser pulse lasting a few billionths of a second with no molecular fragmentation. Applications focus on: (1) benzene clusters, excimers, and exciplexes; (2) metal clusters; and (3) triplet formation and decay. (Author/JN)

Free radical chlorination of methane is used in organic chemistry to introduce free radical/chain reactions. In spite of its common occurrence, demonstrations of the reaction are uncommon. Therefore, such a demonstration is provided, including background information, preparation of reactants/reaction vessel, introduction of reactants, irradiation,…

Discusses chemometrics (analysis of data from chemical measurements), tracing developments in this area and summarizing reasons for teaching chemometrics. Includes highlights of presentations given at a symposium (Interpreting Complex Chemical Data: Teaching Chemometrics) and brief descriptions of chemometric methods. (JN)

Describes an experiment on the qualitative analysis of several over-the-counter analgesic tablets. Background information, procedures used (including high pressure liquid chromatography), and typical student results are included. (JN)

The reaction between arsenite and iodate in acidic solution offers an excellent pedagogic introduction to such phenomena as traveling waves. Component reactions, traveling waves, and a mathematical model are discussed. Demonstrations described can easily be elaborated into a full laboratory experiment. (Author/JN)

A Beckmann arrangement was developed which explores the concept of stereospecificity and concurrently exposes students to synthetic, spectrophotometric, and chromatographic processes. Background information, laboratory procedures, and results are provided. (JN)

Hydantoins are a drug family lying within the broadly related ureide structural frame which encompasses many of the anticonvulsant drugs used in treatment of various types of epilepsy. Background information and experimental procedures are provided for the synthesis of the hydantoin 5,5-diphenylhydantoin. (JN)

Describes a simple, inexpensive electronic circuit used as a small analog computer in an experimental approach to the study of oscillations. Includes circuit diagram and an example of the method using steps followed by students studying underdamped oscillatory motion. (JN)

Describes a three-hour experiment designed to introduce students to chemistry of the angiotensis-converting enzyme, illustrate design of a quenched fluorescence substrate, and examine considerations necessary in designing a clinical assay. Includes background information on the biochemistry of hypertension, reagents/materials needed, procedures…

Suggesting that the evolutionary record may be written in proteins and genes, discusses research in which species are compared by immunology, DNA, and radioimmunoassay. Molecular studies show that DNA from humans and chimps is 98 percent identical, a degree of similarity usually occurring only among animals of the same genus. (JN)

Describes an experiment in which static/dynamic properties of a helical, steel spring are investigated. During the experiment students discover that the behavior of the springs is non-Hookean at small loads. Background information (including static deflection and period of oscillation) and typical results are provided. (JM)