In the context of Nobel prize awards, another commentary might be of interest and particularly useful to those of us who teach courses for non-science majors. The article in the August 1 issue, entitled "A Nobel Tale of Wartime Injustice" by E. Crawford et al. (vol. 382, pp 393-395) summarizes evidence from recently released documents of the Royal Swedish Academy of Sciences that sheds light on the question why Otto Hahn alone was given the prize in chemistry for his discovery of nuclear fission, while contributions by his scientific collaborators Lise Meitner, Fritz Strassmann, and Otto Frisch were so obviously ignored.

On the biochemistry/biophysics front, "Another Green Revolution" by S. G. Boxer (October 10 issue, vol. 383, p 484) summarizes recent advances in elucidating the relationship between protein structure and function in green-fluorescent protein (GFP), a bioluminescent protein from a jellyfish that, as its name suggests, emits green light. Interestingly, GFP does not feature a nonprotein chromophore, and its light-absorbing entity is generated by autocatalytic oxidation of a short segment of its polypeptide sequence, a process that takes place even when the protein is made in various other organisms via recombinant DNA technology. By linking the gene for GFP to the DNA encoding a protein of interest, GFP has found widespread application as a "natural" fluorescent marker that allows researchers to track the expression of these protein chimeras and probe their interactions with other proteins by fluorescent microscopy. Other potential uses of GFP include studies of protein folding kinetics and modification of the protein's spectroscopic properties by selective changes in its amino acid sequence through site-directed mutagenesis.

Biomimicry has been raised to a remarkable level with the report in the August 22 issue (vol. 382, pp 697-700) of an artificial nose. Walt and coworkers were able to coat the ends of optical fibers with dyes and one of several polymers that reversibly react with vapor- phase organic compounds that act as scents. As the tips of the fibers are exposed to scent-containing vapors, the dye/polymer mixtures fluoresce to different intensities at given wavelengths, which can be captured as a video signal at the opposite end of the light path. Since the concentration of the scent rises, peaks, and then decreases as the vapor is moved past the multianalyte sensor end of the light fiber, a complex spatiotemporal signature is created for each "odor" and passed to a neural network (Stuttgart Neural Network Simulator, version 3.2). Having been trained with the input signal from several different scent-containing vapors, the neural network is able to correctly identify individual scents at different concentrations with astonishing accuracy. Continuing work will certainly increase the range of compounds that can be sensed and, as pointed out by the authors, such artificial noses potentially have wide applications as environmental and medical monitors. Perhaps just as importantly, the device may shed light on the molecular mechanisms of the sense of smell.

Schematic diagram of artificial nose. (Picture courtesy of Walt and Davidson.)

The seemingly never ending battle between hi-tech counterfeiters and legitimate owners of important documents took an interesting turn with the report in the September 5 issue (vol. 383, pp 58-60) that chemists at the University of Arizona and the University of Connecticut had developed an information encoding system based on a polymer with photorefractive properties. Such materials are able to undergo light-induced changes in refractive index and therefore provide a nonlinear medium in which information can be stored as a function of light phasenot light intensity, as in normal print media. Nearly invisible and therefore difficult to copy, phase masks are included in the protected document to ensure authenticity of the documents. The masks can be detected and decoded by key devices utilizing commercially available low-power laser diodes. The system should be readily applicable to such purposes as credit card verification.