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AbstractInteractions of glucopyranose, fructopyranose and sucrose with a proteinaceous receptor model have been examined to validate the stereomolecular mechanisms of sweet taste proposed for sugars. The methylene groups at C-6 of glucose, at C-1 and C-6 of fructose and at C-6, C-1' and C-6' of sucrose appear to play an important role as dispersive interaction centres with the receptor. 相似文献
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R. Edge M. François L. Seguin M. Kessler J. Houben Leslie Hart F. P. Treadwell H. Biltz W. Biltz und F. Wessel 《Fresenius' Journal of Analytical Chemistry》1931,85(7-8):307-320
Ohne Zusammenfassung 相似文献
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Leslie Hart 《Fresenius' Journal of Analytical Chemistry》1933,95(1-3):62-63
Ohne Zusammenfassung 相似文献
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Meng-Dawn Cheng Leslie KarrJohn Kornuc David StaatThomas Wainman Bryan HarreBarbara Sugiyama 《Microchemical Journal》2002,72(2):209-219
High levels of lead in some occupational environments still exist. These include lead paint abatement sites, smelting operations, small arms firing ranges, and other construction scenarios. New emerging technologies provide the capability to provide an on-site alternative to conventional laboratory methods for airborne lead. In this paper we describe the evaluation of two such technologies using laboratory prepared lead-laden super-micron aerosol particles. Size measurements by TSI Aerodynamic Particle Sizer™ indicated the fluctuation of the peak particle sizes varying less than 1% among different runs for a given solution concentration. The content of lead embedded in the particles varied from 14 to 18% between runs of three different lead solution concentrations. A commercially available instrument for airborne lead measurement, AeroLead™, showed promise of becoming fully validated with the addition of design enhancements, although not fully validated by the end of the research program. Some of these areas being reworked by the manufacturer include working electrode issues, such as a more uniform surface area. Once these have been addressed, the manufacturer plans to complete the field and laboratory validation procedures. In a subsequent study, the ABF-LIPS results shown in this paper indicated that the technology could be used to quantify lead in aerosol form with a signal-to-noise ratio of three or larger of approximately 100 μg m−3 or higher quantity in a few minutes of measurement interval. The estimated detection limit for Pb using the ABF-LIPS prototype was approximately 60 μg m−3. In comparison the Resource Conservation and Recovery Act (RCRA) limit for Pb emission is 250 μg m−3. 相似文献
160.
The behaviour of a biaxial nematic liquid crystal in the presence of electric and magnetic fields is discussed. In terms of the values of the magnetic susceptibilities and the dielectric permittivities, each biaxial nematic compound can be classified to belong to one of thirty-six different states. These states can be grouped together into three different classes, denoted by us as type A, B and C. The states belonging to each class exhibit a different qualitative behaviour in the presence of perpendicular electric and magnetic fields. While type A biaxial nematics always exhibit the same stable configuration in the presence of the fields, type B and C biaxial nematics exhibit two possible stable equilibrium configurations. Which of these is stable is determined by the magnitudes of the applied fields. The exchange of stability for type B systems can be modelled as a second order transition, while the exchange of stability for type C systems is of first order. In addition, the latter type can develop a bistable behaviour if certain conditions for the magnitudes of the electric and magnetic fields are fulfilled. 相似文献