Dead tanning

Qian Z, Tan TC (1998) A model for multicomponent biosensing and its application to dead-base BOD biosensor. Chem Engineer Science 53 3281-3294... 

In practice, a material that is "dead" will store much of the applied energy and has a low resilience and a relatively high tan delta. A material that returns much of the energy has a high resilience and a low tan delta. These properties have an influence on the grades used for shock absorbers, springs, bushes, or wheels. 

DHA works because of a reaction between its carbonyl group and a free amino group (—NH3+) of several amino adds in the skin protein keratin. Amino adds are the building blocks of the biological polymers called proteins (Chapter 19) keratin is just one such protein. The DHA produces brown-colored compounds called melanoids when it bonds to the keratins. These polymeric melanoids are chemically linked to cells of the stratum corneum, the dead, outermost layer of the skin. DHA does not penetrate this outer layer so the chemical reaction that causes tanning only affects the stratum corneum. As this dead skin sloughs off, so does your tan ... 

Within several hours of application, DHA produces a brown skin color by reacting with the outer layer of the skin, which consists of dead cells. Only the dead cells react with DHA, so the color gradually fades as the dead cells slough off and are replaced. This process generally leads to the fading of chemical tans within a few weeks. Another problem with chemical tans is uneven skin color. Areas of skin such as elbows and... 

Calyptrochaeta remotifolia (Mull. Hal.) Z. Iwats., B.C. Tan Touw is the most common and widespread Calyptrochaeta species in Malesia and shows the orthotropic type of growth pattern. Fleischer (1908) reported it growing on rotting bark and dead branches, on soil, and rarely on rocks. Fleischer s habitat description indicates that C. remotifolia occurs in drier habitats than C. ramosa or C. parvireta, but the first author of this paper observed occasionally herbarium specimens of C. remotifolia intermingled with C. ramosa, C. parvireta, or both. 

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