in this issue New Materials in the Curriculum Many of the most exciting advances in science these past several decades have involved new types of materials; polymers, biomolecules, and metals and alloys with unusual solid-state properties are just afew examples. These materials involvefa&nating chemistry and represent the cutting edge of research. Students training to become chemists must become familiar with this newchemistrv if they are to be successful in the workplace; nonmajors A l l enwunter these materials increasinelv in their dav-to-dav lives and would profit from a better Gderstandini of the; make-up and properties. However, the predominence of solution chemistry in both lecture examples and laboratory experiments provides a bamer to the integration of these new technologies and theoretical considerations into the curriculum. Several articles in this issue deal with these modem substances and provide teachers with both theoretical and wactical information for classroom use. The mosdeye-catching new material is the one exhibiting its tricks on this month's cover: the nickel-titanium alloy known as "memory metal". The dramatic realignment of the spectacles from their crumpled, useless state to their original conformation illustrates just one of the practical applications of this material. h i d e from its ahility to make even the most clumsy or absent-minded of us safe from temporary fuzzy vision, this metal exhibits several other useful uhvsical urouerties and. more importantly to teache;, &m be i s e d t o demonstr&e important facets of solid-state theom The nrouerties that make it a curiosity arise from the f&t tha't itundergoes a solidstate change of phase--a phase change seldom discussed in introductory courses. Gisser, Geselbracht, Cappllari, Hunsberger, Ellis, Perepezko, and Lisensky (page 334) give an in-depth review of the theortical aspects of this phenomenon and intersperse their discussion with suggestions for classroom demonstrations and experiments. Last month's issue contained a similarly designed article by Geselbracht, Ellis, Penn, Lisensky, and Stone (March 1994, page 254) that concentrated on providing experiments and demonstrations illustrating the more wmmonly known mechanical properties of metals. Taken together, these articles make a package that should assist teachers at many levels to incorporate a modern unit on solid-state properties. Another class of compounds playing a role in "smart" material develoument are conductine uolvmers. These linear. " solid-state materials' interesting properties derive from their extended rr conjugation and one-dimensional topol- A
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Journal of Chemical Education
om. Sherman. Euler. and Force (uaw . A94) find that p z y a n i l i n e is a n extremely good representative to demonstrate the properties of this interesting class of materials to undergraduates. Not only is it easy and safe to prepare, but its electrochromic properties give it dramatic color changes that attract students a t many levels. Since the color changes also demonstrate important electronic properties and are the basis of its practial applications, experiments can be developed for many types of students. Another important class of polymers that do not always get attention in the undergraduate curriculum are epoxys, even though there can scarely be a classroom that is not filled with products using these versatile resins. Dewprasbad and Eisenbraun (page 290) present a review of the fundamentals of formulating these compounds, discussing their wmposition and the ways in which both composition and properties are controlled during preparation. Biomolecules have become a major component of chemical research as we learn more about the molecular basis of the functioning of living systems. Many of these materials have or are anticipated to have hi-tech applications; genetic eneineerinrr has hewme a fast-erowine industnr that encomp&ses just a few of the impo&nt brochemical discoveries of the past few decades. Several articles in this issue feature important b~omoleculerchemistry. Senozan and Burton (page 222) discuss how hemoelobm acts aq a remarkable rn&cular pump that enables exotic fish to maintain the internal pressure that allows it to live at great depths in the ocean. Artificial amplification of a specific region of DNA has become an important tool in the new biochemistry The commercially used cloning technique is difficult for the undergraduate lab; however, Weller (uaee 340) uoints out that amulification can also be achieved by using the polymerase chain reaction, which requires technical skills that are reasonable for undereraduates, and then gives general directions for its use. Jakubowski, Penas, and Saunders (page 347) offer an experiment on lipids that allows students to study more important and interesting aspects of their chemistry than the usual experiments. Another area of recent interest has grown from the discovery that many plants produce substances that act as chemical defenses against preditors, since these may be a source of "natural" pesticides. Moreno, Puig-Roque, Nevado and Garcia-Ferris (page 350) have devised a n experiment that explores such a compound in beans, which produces selective inhibition of animal enzymes, thus making them difficult to digest in many animals, including humans. .&
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