Systematic behavior of electro-optic chromophore photostability.

The wavelength dependence of the one-photon absorption-induced photodegradation rate has been measured from the visible to the near IR for a variety of electro-optic chromophore-doped polymers. Systematic behavior is identified. The lifetime of the electro-optic activity is found to increase exponentially over 4-6 orders of magnitude for wavelengths ranging from peak of absorption, typically in the visible, to ~1000 nm. Many popular chromophores developed for electro-optics over the past 10 years are compared.

Effect of temperature and atmospheric environment on the photodegradation of some Disperse Red 1-type polymers.

The photodegradation of the azobenzene chromophore DR1 {4-[N-ethyl-N-(2-hydroxyethyl)amino]-4(?)-nitroazobenzene]} incorporated as a side chain or as a guest in a poly(methyl) methacrylate host has been evaluated as a function of wavelength, temperature, and the atmospheric environment. The effects of these variables on the lifetime of DR1-based electro-optic devices is quantified.

[Computed tomography of dentigerous cyst. (Report of a case)]. / Tomografía computada del quiste dentígero. (Informe de un caso).

Although radiological diagnosis is easily and readily performed by orthopanthomography, with lateral oblique and anteroposterior projections, the image of dentigerous cysts may, on some occasions, be confusing. We submit the case history of a patient whose computerized tomography data may be useful in differential diagnosis.