Despite several excellent properties including low shrinkage, good chemical resistance, curable at low temperatures and the absence of byproducts or volatiles, epoxy resins are susceptible to ultra violet (UV) damage and their durability is reduced substantially when exposed to outdoor environments. To overcome this drawback, UV absorbers have been usually used to decrease the rate of UV degrad...

Secondary organic aerosol (SOA) particles are generated by reacting d-limonene vapor and ozone in a Teflon reaction chamber. The reaction is carried out in either dry or humid air in darkness. The resulting SOA particles are collected on glass fiber filters, and their photochemical properties are probed using a combination of UV photodissociation action spectroscopy and absorption spectroscopy ...

We present and discuss our observations of the Narrow Line quasar PG1404+226 (zem = 0.098) with ASCA and HST, and a re-analysis of our earlier observations with ROSAT. The soft X-ray spectrum is very steep and displays an absorption feature (edge or line at ∼ 1.1 keV). We have applied a variety of models to the ASCA and ROSAT spectra without finding a completely satisfactory fit, and the identi...

To study the nature of low z Lyα absorbers in the spectra of QSOs, we have obtained high signalto-noise UV spectra of H 1821+643 (zem = 0.297) and PG 1116+215 (zem = 0.177) with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The spectra have minimum S/N ∼ 70-100 and 3σ limiting equivalent widths of 50-75 mÅ at a resolution of ∼150 km s. Excluding lines within 3000 km s ...

Azobenzenes have a unique ability to undergo reversible isomerization between two geometrical isomer forms (the straight trans and the bent cis) when irradiated with the correct wavelength of UV or visible light. These systems are of interest because of their numerous potential applications as reversible photoswitchable absorbers. The azobenzenes can also be used as terminal groups in nickel di...