Market trials of irradiated chicken

The potential market for irradiated chicken breasts was investigated using a mail survey and a retail trial. Results from the mail survey suggested a significantly higher level of acceptability of irradiated chicken than did the retail trial. A subsequent market experiment involving actual purchases showed levels of acceptability similar to that of the mail survey when similar information about food irradiation was provided.     

Heterogeneous photosensitization—III the benzaldehyde photopolymer photosensitization of the 1,3-pentadienes in the gas phase [1]

The i.r. absorption spectrum of benzaldehyde photopolymer, formed by photolysis of benzaldehydc: (λ > 300 nm, T = 50°) in a Pyrex cell, shows the absence of specific benzoin absorption at 10·2 μm. The kinetics of the photopolymer sensitized cis ? trans isomerization of the 1.3-pentadienes have been studied for λ > 300 nm and pentadiene pressures between 1 and 470 torr. The luminescence excitation spectra of the photopolymer, the Stern- Volmer plots, and the photostationary state ratios of the 1.3-pentadienes all indicate the presence of two different types of active chromophores in the photopolymer.     

Elemental fluorine. Part 18. Selective direct fluorination of 1,3-ketoesters and 1,3-diketones using gas/liquid microreactor technology

1,3-Ketoesters and 1,3-diketones react with fluorine gas, using Durham multichannel modular microreactor technology, on a preparatively useful scale. High conversions and yields of monofluorinated products were obtained. A consideration of the mechanism of fluorination of dicarbonyl systems provides a rationale of the scope and limitations of the use of microreactor technology for such direct fluorination processes. We conclude that it is especially appropriate for the fluorination of diketones and ketoesters that exist mainly in the enol form at equilibrium and/or undergo rapid keto-enol interconversion. A one-stage route to fluoroketones from ketoesters was achieved by allowing the crude product mixture obtained from the fluorination of the ketoesters to stand for a period of time before reaction work-up.     

Construction of the Jordan basis for the Baker map

The Jordan canonical form basis states for an invertible chaotic map, the Baker map, are constructed. A straightforwardly obtained recursion formula is presented for construction of the Jordan states and of the spectral decomposition of the Frobenius-Perron evolution operator. Comparison of this method with earlier, subdynamics techniques demonstrates that it is much more direct and simpler. The physical significance of the Jordan states is approached from the point of view of an entropy evolution equation. The method is also applied to the Bernoulli map, yielding its eigenstates more straightforwardly than done previously. (c) 1997 American Institute of Physics.     

Coordination chemistry of silver cations

While in pure solvents Ag(+) is known to be tetrahedrally coordinated, in the presence of ligands such as ammonia it forms linear complexes, usually explained by the ion's tendency toward sd-hybridization. To explore this disparity, we have investigated the reaction of ammoniated silver cations Ag(+)(NH(3))(n)(), n = 11-23, with H(2)O as well as the complementary process, the reaction of Ag(+)(H(2)O)(n)(), n = 25-45, with NH(3) by means of FT-ICR mass spectrometry. In both cases, ligand exchange reactions take place, leading to clusters with a limited number of NH(3) ligands. The former reaction proceeds very rapidly until only three NH(3) ligands are left, followed by a much slower loss of an additional ligand to form Ag(+)(NH(3))(2)(H(2)O)(m)() clusters. In the complementary process, the reaction of Ag(+)(H(2)O)(n)() with NH(3) five ammonia ligands are very rapidly taken up by the clusters, with a much less efficient uptake of a sixth one. The accompanying DFT calculations reveal a delicate balance between competing effects where not only the preference of Ag(+) for sd-hybridization, but also its ability to polarize the ligands and thus affect the strength of their hydrogen bonding, as well as the ability of the solvent to form extended hydrogen-bonded networks are important.     

Gas chromatography—mass spectrometry studies on the occurrence of acetamide,propionamide, and furfuryl alcohol in pyrolyzates of bacteria,bacterial fractions,and model compounds

Fused-silica capillary gas chromatography—mass spectrometry was employed to investigate the production of several bacterial pyrolysis products, including acetamide, propionamide, and furfuryl alcohol. A variety of model compounds, selected for their similarity with bacterial structures, were pyrolyzed and amounts of these pyrolysis products were quantitatively determined. Model compounds included several analogues of muramyl dipeptide differing in chain length at the lactyl—peptide bridge as well as several neutral and amino sugars, amino acids, and nucleic acids. Bacterial cell walls and whole microbial cells were also analyzed. Measurement of the amounts of a few chemically identified pyrolysis products provides some chemotaxonomic differentiation of microorganisms, as demonstrated by the pyrolysis of a group of Gram-positive and Gram-negative bacteria (including samples of Legionella pneumophila), and fungi.     

The effective molecular polarizability and local electric field in molecular crystals

The problem of calculating the effective molecular polarizabilities and the local electric fields in molecular crystals is considered. It is shown that in a crystal with two or more anisotropic molecules per unit cell, these quantities cannot be found from the crystal structure and the dielectric tensor alone.     

The simultaneous use of solute vapor pressure and geometry in multidimensional capillary gas chromatographic separations of polychlorinated biphenyls

The separation of coeluting congeners of Aroclor 1242, 1254, and 1260 on a DB-1 (low polarity) capillary gas chromatographic (GC) column is achieved when cuts of those peaks are transferred onto a smectic liquid crystalline column, which is commercially available. This procedure requires the use of a gas chromatograph equipped with two independent ovens for optimizing the temperature conditions of each column. Excellent base line separations are achieved on multicuts, up to six, of the same injection. This unique multidimensional/multimodal capillary GC system, in which the two separation modes of vapor pressure and molecule geometry are employed, is a powerful analytical technique for the separation of complex organic mixtures.     

Photochemistry and spectroscopy of "stable organic radicals": steric and electronic effects in intermolecular photoinduced electron transfer

The intermolecular reactivities of amino-substituted perchlorotriphenylmethyl radicals 1-3 were studied, with particular emphasis on electron transfer (ET) reactions. The natural fluorescence lifetimes and the rates of the electron-transfer quenching were studied with several electron donors and acceptors. Fluorescence quenching studies demonstrate the importance of the redox potentials of the ET pair on the observed steric and electronic properties.