Describes an experiment in which undergraduate students can do simple Huckel Molecular Orbital (HMO) calculations from spectral data for a series of four closely related dyes. (JN)

Describes two frequently used DNA sequencing methods: Sander's enzymatic dideoxy method and Maxam and Gilbert's chemical sequencing method. Indicates that studying these methods provides students with knowledge of the chemical structure of DNA and how DNA sequence data are obtained. (JN)

Discusses (1) characteristics, interrelationships, and distribution of food constituents (including water) in unfrozen food systems; (2) the freezing process; and (3) chemical changes in food during frozen storage. Protein alterations and lipid oxidation are emphasized. (JN)

Traces the history of the electron theory of the chemical bond. Nineteenth-century ideas on electrical combination, early twentieth-century theories of electrical attraction, and the contribution of G. N. Lewis's shared electron pair are among the topics considered. (JN)

Discusses the valence-bond method, applying it to some coordination compounds of metals, especially those involving metal-metal bonds. Suggests that transition metals can form as many as nine covalent bonds, permitting valence-theory to be extended to transition metal compounds in a more effective way than has been possible before. (JN)

To enhance the nation's economic productivity and improve the quality of life worldwide, engineering education in the United States must anticipate and adapt to the dramatic changes of engineering practice. The Engineer of 2020 urges the engineering profession to recognize what engineers can build for the future through a wide range of leadership…

Discusses the use of the properties of polyethylene, polypropylene, polyisobutylene, and their three epoxides to illustrate the relationships of entropy to molecular properties and the concepts of molecular chirality, geometry, and flexibility. (CC)

A storage and retrieval system for chemical structures, using optical coincidence, is in use at Schering Corp. The system rapidly provides the research laboratories with structural information at any generic level. The design, maintenance, costs, and applications are discussed. (4 references) (Author)

A computer system, named CORA, has been devised for coding chemical structures by fragmentation elements. It has been used to encode Markush formulas in patents according to the Ring codes used in the Ringdoc and Pestdoc services and results in an easy, speedy, reliable and inexpensive method. (4 references) (Author)

The set reduction algorithm is based on set theory and Boolean algebra rather than the graph-theoretic approach. Time trials with a small file of organic chemical structures indicate that the algorithm can be economically used for substructure (or complete structure) sequential searches on a file containing 30,000-50,000 computer-coded structures.…

The temperature at which the onset of coordinated segmental motion begins is called the glass-rubber transition temperature (Tg). Natural rubber at room temperature is a good example of a material above its Tg. Describes an experiment examining the response of a typical polymer to temperature variations above and below Tg. (Author/JN)

The statement is sometimes made in textbooks that liquid hydrogen peroxide is more strongly associated than water, evidenced by its higher boiling point and greater heat of vaporization. Discusses these and an additional factor (the nearly double molecular mass of the peroxide), focusing on hydrogen bonds and structure of the molecule. (JN)

Although polymers are regarded as electrical insulators, it was discovered that they can be made to conduct electricity. This discovery has opened vast new practical and theoretical areas for exploration by physicists and chemists. Research studies with these conducting polymers and charge-transfer salts as well as possible applications are…

Use of combined liquid chromatography and finite-current electrochemistry (LCEC) procedures are discussed. Also discusses the relationship between electroactivity and molecular structure, selectivity in LCEC, and LCEC applications. Because of its selectivity and low detection limits, the procedures are most often applied in biomedical and…

Wiswesser Line Notation, a system for representing structural formulas by a single line of common symbols (numerals, capital letters, and three punctuation marks), is gaining acceptance as an effective indexing tool. The resulting notations, denoting specific structural fragments of a molecule, can be retrieved by humans or computer. (Author/JN)