Integrated optical techniques and resonance Raman spectroscopy have been combined to investigate the intermolecular interactions at dye/polymer and dye/glass interfaces. Frequency shifts and intensity changes of bands assigned to the stretching vibrations of the bridged quinoline rings of the cyanine dye chromophore have been utilized to gain insight into the relative strength of adhesive forces at the surface. Polarized Raman measurements were made to determine the orientation of the chromophores on a poly(vinyl alcohol) surface. This was done to assess the possibility of hydrogen bond formation between the ring nitrogen atoms and the polar hydroxyl groups at the surface. 相似文献
The preparation of 5-hydroxy-4-nitroso- and 7-hydroxy-4-nitrosobenzofurazan as well as of their 6-chloro and methyl derivatives is described and the oxime structure of these compounds is established. NMR spectra of benzofurazan-4,5-dione-4-monoxime and benzofurazan-4,7-dione-4-monoxime show evidence for an interconversion, in solution, of two monoximes, the 4,5- and 4,7-derivative prevailing in organic solvents and aqueous alkaline media, respectively. Chloro and methyl derivatives of benzofurazan-4,5- and 4,7-dione-4-monoximes show a similar interconversion in organic solvents. 相似文献
Cross‐linked polymers of intrinsic microporosity (PIM)s for gas separation membranes, were prepared by a nitrene reaction from a representative PIM in the presence of two different diazide cross‐linkers. The reaction temperature was optimized using TGA. The homogenous membranes were cast from THF solutions of different ratios of PIM to azides. The resulting cross‐linked structures of the PIMs membranes were formed at 175 °C after 7.5 h and confirmed by TGA, XPS, FT‐IR spectroscopy and gel content analysis. These resulting cross‐linked polymeric membranes showed excellent gas separation performance and can be used for O2/N2 and CO2/N2 gas pairs, as well as for condensable gases, such as CO2/CH4, propylene/propane separation. Most importantly, and differently from typical gas separation membranes derived from glassy polymers, the crosslinked PIMs showed no obvious CO2 plasticization up to 20 atm pressure of pure CO2 and CO2/CH4 mixtures.
This paper introduces and analyzes a model of supervised work group where subordinates decide how to exert their effort in complementary tasks while the supervisors decide incentives. Incentives may be a combination of individual and group-based ones. The optimality of incentives is analyzed when considering two different cost functions for subordinates. The two cost functions describe different individual motivations; comparing the resulting effort allocations and production optimality, we can relate them to different organizational theories. Our results provide a measure of how motivation among subordinates may affect production and incentives. Furthermore, the optimal incentives schemes are examined in terms of Adams’ equity theory. 相似文献
3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) is known for its toxicological, psychopathological and abuse potential.
Some environmental conditions, e.g. acoustic stimulation typical of the "rave scene" can influence the toxicity of this drug. 相似文献