Chemical signals release rate

One may wonder why lobsters appear to use urine as a dispersal solvent for chemical signals, whereas terrestrial arthropods such as the well-studied insects use direct release of gland products into the air. Perhaps the answer is that small animals in air (such as insects) are always in danger of desiccation. By contrast, marine lobsters and crabs are relatively large and may experience only minor water loss problems due to osmosis. Thus, it may not be difficult for a 500-g lobster to store 10 ml of urine and release it during a dominance battle at a rate of up to 1 ml/min (27). The advantage of urine-carried pheromones is that the dispersal mechanism already exists urine is injected into the gill current, which in turn injects into ocean currents. 

Other environmental cues, such as water shortage, cause plants to transmit chemical signals to the guard cells, causing them to release potassium, which increases their osmotic potential, and to lose water by osmosis. This causes the guard cells to shrink, so closing the stomata, and decreasing the rate of water transpiration... 

Bossert and Wilson (1963) showed that the ratio of the natural pheromone release rate to the behavioral threshold (Q/K) is a fundamental characteristic of different communication systems. In some communication functions such as with alarm pheromones it is imperative that the signal fade quickly. Organisms producing alarm pheromones generally have a high value of Q/K. Other chemical communication systems such as sex pheromones utilize a relatively persistent signal, characterized by low Q/K ratios. Q/K ratios in different organisms and communication systems are summarized by Matthews and Matthews (1978). 

The material factor (MF) is the basic starting value in computation of the F EI and other risk analysis values. It is a measure of the intrinsic rate of potential energy release from fire or explosion produced by combustion or other chemical reaction. The MF is obtained from Ns and Nr, NPFA signals expressing flammability and reactivity (or instability), respectively. The values for many materials are found in NFPA 325M or NFPA 49. Dow has developed values for additional materials and published them as an appendix of the F EI Guide. ... 

Many analyses easily cross industry fines. The chemical and pharmaceutical industries are interested in the analyses that determine the coating weight of a coated particle such as with a time-released dmg. Like the spin finish on fibers, the coating has a different relaxation rate than the encapsulated material. Fluorine analysis is another unique application of NMR technology since the signal derives from the fluorine nuclei rather than hydrogens. The materials for which this technique for process analysis and control might be used include toothpaste, fluoropolymers and fluorochemicals. 

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