Absorptivities, hydrophobe-containing

Absorption bases contain small amounts of water. They provide relatively less emollient properties than hydrocarbon bases. Similar to hydrocarbon bases, absorption bases are also difficult to remove from the skin due to their hydrophobic nature. Hydrophilic petrolatum USP and lanolin USP are examples of absorption bases. 

Absorption is widely used as a raw material and/or product recovery technique in separation and purification of gaseous streams containing high concentrations of VOC, especially water-soluble compounds such as methanol, ethanol, isopropanol, butanol, acetone, and formaldehyde. Hydrophobic VOC can be absorbed using an amphiphilic block copolymer dissolved in water. However, as an emission control... 

Dialkylanthracene-containing squaraine dyes 17 show intense absorption and emission in the NIR region (720-810 nm) [74]. They are compatible with aqueous environments and show substantial enhancement of quantum yields and fluorescence lifetimes in hydrophobic and micellar media, suggesting that these dyes can be potentially useful as fluorescent probes in biological applications, e.g., for imaging of hydrophobic domains such as cell membranes. 

Phenylalanine and tryptophan contain aromatic side chains that, like the aliphatic amino acids, are also relatively non-polar and hydrophobic (Figure 1.4). Phenylalanine is unreactive toward common derivatizing reagents, whereas the indolyl ring of tryptophan is quite reactive, if accessible. The presence of tryptophan in a protein contributes more to its total absorption at 275-280nm on a mole-per-mole basis than any other amino acid. The phenylalanine content, however, adds very little to the overall absorbance in this range. 

The sorption of non-polar organic hydrophobic substances to solid material that contain organic carbon must be interpreted as "absorption", i.e., a "dissolution" of... 

Crown ethers are not chromogenic unless they contain a pendant chromogen able to dissociate a proton in a basic medium. The resulting anion interacts strongly with the crown-complexed cation compensating the electric charge. The formation of a zwitterion leads to a hydrophobic extractable species with a considerably shifted absorption maximum compared with the protonated species. This allows the same spectrophotometric determination to be used for a large number of metal ions, provided the appropriate crown compound is used in each case. Another method involves... 

In North America the problem of moisture absorption has been addressed by developing a moisture resistant gunpowder substitute based on potassium nitrate but augmented with potassium perchlorate. The latter is said to absorb less moisture than the nitrate at a given humidity. In addition, the gunpowder substitute contains a hydrophobic binder, called ethyl cellulose, (2.22) (celluloses have a history of use in pyrotechnics) together with an organic fuel, known as phenolphthalein, (2.23) which is said to enhance the bum rate. 

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